Need some professional advice on cams

[TomsSVX]

I have been thinking about what we can do with our cams. This thread is for those of you who know more about the technical points about them.

As of now we are able to weld and grind our intake cams to 8mm of lift with 240 degrees of duration. Stockers are 7mm of lift with 236 degrees of duration. Now this gives us a nice noticable improvement in power without sacrificing any drivability on the street.

I, however am looking to do something a little more radical with my next set. Since Delta Cams has provided me with a good price on cams I don't want to go anywhere else, but they are limited to pre-set profiles. That being said, lets talk about what else we can do.

I did a little research and I found that the most vital parts of designing a camshaft is the overlap... Increase the overlap and you will increase your upper rpm power but lose down low and have a "rougher" idle. This is what I am looking to do but not so far that it cannot be driven normally. Now say we stick with the 240 degrees of duration, what if we were to offset the cam teeth a little? I mean each cam sprocket contains 50 teeth which means each tooth is worth 7.2 degrees.

Oh, almost forgot. The exhaust cam profile is 8mm of lift with 244 degrees of duration.

With this information, what configuration would be optimal for a person looking to increase their high end power on a stock block?

Thanks for your help and please limit comments an questions to ones that are well educated

Tom

[oab_au]

I'll start by saying that each cam does its own function. The lnlet has to provide enough lift and duration to suit the rpm that we want the engine to produce its miximum power at. The exhaust has to be able to release the gas pressure that is still in the cylinder, it enough time, so that there is no pumping of exhaust gas as the piston rises on the exhaust stroke.

The two cams are seperate, they don't have any relationship together, they are two separate functions, and have to be seen that way. Now I know that this is not what you read from the "tuners", as Tom has said they are tied up in 'valve overlap'. This is a result of the two cam settings, and have little effect on the way the cams are set.

If we look at what Tom has quoted," that we can just vary the overlap to do the job. If we incress the overlap with the standard cams, we would advanced the inlet lobe center, and retard the exhaust, which would have the torque appear lower in the rev range, not higher.

This is going to go against 'what they say' but this is the case. The change from two valve to four valves, has changed the way we do and think, about it. The four valve engine has superior breathing at high rpms. To give an example, a two valve engine, of 550cc cylinder size, would use a lift of 10 to 12mm, and a duration of 360* to have the torque at 7500. The same cylinder with four valves uses 9mm lift and 260* to produce more torque at the same rpm.

Harvey.;)

[oab_au]

On the example of the two/four valve engines.
The two valve that I gave has an inlet valve of 42mm and 12mm lift. Useing a valve throat dia of 40mm, the area of the valve circumference at full lift is = 1507 sqmm.
The eg33 has a 37mm valve, throat of say 35mm - 6mm for the valve stem = 934sqmm. At 8.5mm lift it has a circumference area of 934 sqmm X 2 valves = 1868sqmm.

This is why we don't need the big durations or lifts, that we did back then, to achive the breathing at high rpms.

Harvey.;)

[SVXRide]

Harvey,
So, are you saying there is little to no benefit of increasing the exhaust cam duration by, say 5-6 degrees (keeping the lift stock)?
-Bill

[TomsSVX]

Ok, thanks Harvey. I am beginning to understand a little better now. I am still confused as to what our best alternative would be, or have we already found it? This thread is here for the full purpose of trying to find our absolute best option. I am looking to make peak power around 6000-6500 rpm. I say this because my 6 speed is using the higher rpms. This is where I would need my power. autos would probobly be better making top power from 5500 to 6000 as it would be dead center of their drawn out shifts

Tom

[oab_au]

I would like to continue to show why, the way we go after power has changed, with the introduction of four valve engines. It will explain why the things that we used, to modify a two valve, and what most hot-up books have taught us to do, no longer are the way.

When we worked a two valve, we used the biggest inlet valve that we could fit in the head. The biggest lift that the valve gear could operate, and the most duration that would allow the engine to start and idle. To assist cylinder filling we used the energy in the inertia of the inlet and exhaust gas. At the end of the inlet stroke, we relied on the inertia of the incoming gas to keep it flowing into the cylinder even though the piston is rising, forcing more gas into the cylinder. We used the inertia of the exhaust gas to create a vacuum in the cylinder, so the inlet gas would be sucked into the cylinder, when the inlet valve open, on valve overlap. To get the engine to operate at high rpms, long duration's were used, inlet valves opened at 60* before TDC, and the exhaust didn't close till after 50* after TDC, valve overlaps in the 100* to 140* were used. Even with all this, it was difficult to get the engine to produce power over 6000 rpm, and still have it with a useable low rpm torque.

The reason for this was in the type of energy we used to perform the cylinder filling. The gas inertia was too slow to allow the filling as the rpm increased. With the coming of the four valve, there was no need for the long duration's, and high valve lifts, as the four valves provided the breathing to run into the 6 to 7000 rpms, without the need for it. As we sort more HP at the higher rpms, we had to use a faster energy source to assist cylinder filling. Sonic pressure waves took the place of the gas inertia. We use a tuned length, resonate inlet tract, that develops negative pressures in the cylinder to draw more gas in.
Instead of a vacuum to start the inlet flowing at valve overlap. We use the sonic pressure waves developed in the exhaust pipe to develop a negative pressure in the cylinders combustion chamber, to deliver an intense start to the sonic pressure wave that will travel the tuned inlet tract, to produce the negative inlet pressures, that will fill the cylinder.

The change from inertia energy, to sonic pressure, has allowed us to rev the engine as hard as we like, as instead of the energy decreasing as the rpm rises, the sonic pressures become more intense as the speed rises. This changes the way we build exhaust systems, as they are the providers of cylinder filling. It is more important to create an intense start to the inlet pressure wave, than to use valve over lap to draw the air in.

This is why the modern four valve engine is so different to the older two valve, in its tuning, but that is progress, and we have got to move with it or fall behind.

Harvey.;)

[SVXRide]

I would like to continue to show why, the way we go after power has changed, with the introduction of four valve engines. It will explain why the things that we used, to modify a two valve, and what most hot-up books have taught us to do, no longer are the way.

When we worked a two valve, we used the biggest inlet valve that we could fit in the head. The biggest lift that the valve gear could operate, and the most duration that would allow the engine to start and idle. To assist cylinder filling we used the energy in the inertia of the inlet and exhaust gas. At the end of the inlet stroke, we relied on the inertia of the incoming gas to keep it flowing into the cylinder even though the piston is rising, forcing more gas into the cylinder. We used the inertia of the exhaust gas to create a vacuum in the cylinder, so the inlet gas would be sucked into the cylinder, when the inlet valve open, on valve overlap. To get the engine to operate at high rpms, long duration's were used, inlet valves opened at 60* before TDC, and the exhaust didn't close till after 50* after TDC, valve overlaps in the 100* to 140* were used. Even with all this, it was difficult to get the engine to produce power over 6000 rpm, and still have it with a useable low rpm torque.

The reason for this was in the type of energy we used to perform the cylinder filling. The gas inertia was too slow to allow the filling as the rpm increased. With the coming of the four valve, there was no need for the long duration's, and high valve lifts, as the four valves provided the breathing to run into the 6 to 7000 rpms, without the need for it. As we sort more HP at the higher rpms, we had to use a faster energy source to assist cylinder filling. Sonic pressure waves took the place of the gas inertia. We use a tuned length, resonate inlet tract, that develops negative pressures in the cylinder to draw more gas in.
Instead of a vacuum to start the inlet flowing at valve overlap. We use the sonic pressure waves developed in the exhaust pipe to develop a negative pressure in the cylinders combustion chamber, to deliver an intense start to the sonic pressure wave that will travel the tuned inlet tract, to produce the negative inlet pressures, that will fill the cylinder.

The change from inertia energy, to sonic pressure, has allowed us to rev the engine as hard as we like, as instead of the energy decreasing as the rpm rises, the sonic pressures become more intense as the speed rises. This changes the way we build exhaust systems, as they are the providers of cylinder filling. It is more important to create an intense start to the inlet pressure wave, than to use valve over lap to draw the air in.

This is why the modern four valve engine is so different to the older two valve, in its tuning, but that is progress, and we have got to move with it or fall behind.

Harvey.;)

Harvey,
Great stuff! Like Tom stated, your discussion in this post is helping me "get my head" around the essentials associated with a DOHC, 4 valve engine! Thanks!
-Bill

[TomsSVX]

Thnx again Harvey, I grew up in a world of cammed out Chevy 350's and this discussion has helped me understand the differences between a pushrod 2valve and the OHC 4 valve.

Tom

[oab_au]

Deciding what cam to use, is really deciding what the engine needs, to do what we want it to. Of course every one says more power,:D so we need to find out why it won't do that now. To do that we have to look at the torque curve to see what is happening to the breathing. This shows that the torque,thus the breathing, is taking a nose dive after 4800 rpm. this can be caused by either the inlet area is restricting the air flow, or the inlet valve is not staying open long en ought to feed it as the rpm rises, or any number of things like a restricted exhaust or inlet,etc.

Seeing that it drops quickly after 4800, it won't be the duration, as it would slowly drop off as the rpm rise. So that suggests that the inlet is restricted. We know, thanks to Mychailo, that the pressure in the plenum is almost atmospheric, at full throttle, so it can't be any restriction in the air cleaner or throttle bodys. The inlet ports, can flow enough, thanks to VTSuby, so that leaves the valves themselves. At 37mm they are as big as any that I have seen, in a 4 valve, just leaves the lift.

This was my first assumption, as the designers wanted to keep the engine noninterference, they worked around a low lift. So we increased the lift by 1mm. This should have allowed the breathing to continue building torque as the rpm rises higher. Won't take the torque peak much higher, as the efficiency is very good as it is, but will allow that efficiency to continue higher up the rpm range. This will have the HP increase to a higher peak at a higher rpm.:)

At this point we do a dyno or a G-Tec run to see if the change we made, is doing what we wanted, (still waiting :p ) as there is no point in going to more duration, if it is not needed, as these things have side effects that we may be able to do with out, like the exhaust and inlet system resonate length.

The big change starts when we extend the duration. This will move the torque peak higher up the rpm range. This will, necessitate a change to the exhaust, to prevent interference between cylinders, and a change to the resonate length of the exhaust and inlet tract, to move the resonate peak up to where the cams have taken the torque peak.

There can be no doubt that this engine can produce high HP at higher rpms. It can go as high as the rods and pistons will allow it. I feel that it can run to around 7500/8000, with the necessary valve gear to match, but the whole set of things, cam, exhaust, inlet tract, valve gear, has to be done together, you can't just do the cams and expect the thing to work on its own, won't happen.:)

Just need to get some feed back to see the way ahead.

Harvey.;)

[TomsSVX]

Well the feedback is going to have to wait. I need to do some stock runs, cammed runs and then see if we are making what we want. So that mean I have to order another set of cams for my silver car. In this case I am not going to want to spend another 300-600 dollars on research as I cannot afford to do so. I will try and get the info out there for you but I will more than likely stick with the same setup I had in the 5speed and leave it be. I do not have the money or the time to keeping changing my cams while shooting in the dark. Sorry... I know this is what we need to know to make it more efficient but I cannot do it on my own. Not to mention you will get more consistant #'s out of an auto rather than a 6mt anyway.

Tom

[oab_au]

Well the feedback is going to have to wait. I need to do some stock runs, cammed runs and then see if we are making what we want. So that mean I have to order another set of cams for my silver car. In this case I am not going to want to spend another 300-600 dollars on research as I cannot afford to do so. I will try and get the info out there for you but I will more than likely stick with the same setup I had in the 5speed and leave it be. I do not have the money or the time to keeping changing my cams while shooting in the dark. Sorry... I know this is what we need to know to make it more efficient but I cannot do it on my own. Not to mention you will get more consistant #'s out of an auto rather than a 6mt anyway.

Tom

Thats OK Tom, don't worry about it,:) You did well, you showed it does work in practice, on the strip.:eek: :D

Harvey.;)

[dynomatt]

The consensus is that the standard valve springs coil bind at about 9mm.

Can lifts of 10mm be obtained with a simple change in springs? Or are there inherent design problems necessitating an entire valve and spring change?

Has anybody measured the diameter of the hydraulic lash adjuster? This will also determine maximum cam lifts before the lobes try to rip off the lash adjusters.

Thanks,
Matt

[oab_au]

The consensus is that the standard valve springs coil bind at about 9mm.

Can lifts of 10mm be obtained with a simple change in springs? Or are there inherent design problems necessitating an entire valve and spring change?

Has anybody measured the diameter of the hydraulic lash adjuster? This will also determine maximum cam lifts before the lobes try to rip off the lash adjusters.

Thanks,
Matt

Oh Matt,I still owe you a PM, sorry about that. 10mm is just too much, and is not needed. The engine breathes really well with the 8mm we went to, lost a bit of the bottom end, more would lose more, with little to add to the top.

The cams used really need to be suited to the transmission used, the 3.5:1 auto is best with the 8mm lift and normal duration. If a 6 speed is used, and one is willing to use all the gears:) I would suggest 8.5mm inlet, 8 mm exhaust, with a duration of about 250/257*along with the necessary springs. Can still run hydraulic lifters, or go to solids.

If the lobes are built up, the lobe can still clear the side of the lifter well, some body checked, I think it was 9mm to touch.?:confused:

Harvey.;)

[TomsSVX]

So Harvey, I will soon be in the market for a second set of cams. This time for the silver. You would suggest a 8.5mm lift on the intakes with 250* duration and exhaust with 8mm of lift with 257*? Just making sure this is what you are suggesting

Tom

[dynomatt]

I thought VTSuby's thread mentioned that he got peak flow of 255cfm (which is Australianised to about 150cfm) at about 10.5mm lift?

I'm talking in a competition sense, where, using the 6 speed, and revving the engine to around 7000-7500rpm, I would have thought this lift would have delivered the right power.

No arguments on the duration either (assume that's at .050"?) but the possibility exists to get more with more duration?

Or has all of my other learnings taught me wrong?

And I've read a bunch of the other threads now...but this isn't keeping the automatic, is going for bigger injectors and includes better air intake, exhausts and upping the compression oh and getting an aftermarket ECU.

Matt

[Trevor]

I would like to continue to show why, the way we go after power has changed, with the introduction of four valve engines. It will explain why the things that we used, to modify a two valve, and what most hot-up books have taught us to do, no longer are the way.

When we worked a two valve, we used the biggest inlet valve that we could fit in the head. The biggest lift that the valve gear could operate, and the most duration that would allow the engine to start and idle. To assist cylinder filling we used the energy in the inertia of the inlet and exhaust gas. At the end of the inlet stroke, we relied on the inertia of the incoming gas to keep it flowing into the cylinder even though the piston is rising, forcing more gas into the cylinder. We used the inertia of the exhaust gas to create a vacuum in the cylinder, so the inlet gas would be sucked into the cylinder, when the inlet valve open, on valve overlap. To get the engine to operate at high rpms, long duration's were used, inlet valves opened at 60* before TDC, and the exhaust didn't close till after 50* after TDC, valve overlaps in the 100* to 140* were used. Even with all this, it was difficult to get the engine to produce power over 6000 rpm, and still have it with a useable low rpm torque.

The reason for this was in the type of energy we used to perform the cylinder filling. The gas inertia was too slow to allow the filling as the rpm increased. With the coming of the four valve, there was no need for the long duration's, and high valve lifts, as the four valves provided the breathing to run into the 6 to 7000 rpms, without the need for it. As we sort more HP at the higher rpms, we had to use a faster energy source to assist cylinder filling. Sonic pressure waves took the place of the gas inertia. We use a tuned length, resonate inlet tract, that develops negative pressures in the cylinder to draw more gas in.
Instead of a vacuum to start the inlet flowing at valve overlap. We use the sonic pressure waves developed in the exhaust pipe to develop a negative pressure in the cylinders combustion chamber, to deliver an intense start to the sonic pressure wave that will travel the tuned inlet tract, to produce the negative inlet pressures, that will fill the cylinder.

The change from inertia energy, to sonic pressure, has allowed us to rev the engine as hard as we like, as instead of the energy decreasing as the rpm rises, the sonic pressures become more intense as the speed rises. This changes the way we build exhaust systems, as they are the providers of cylinder filling. It is more important to create an intense start to the inlet pressure wave, than to use valve over lap to draw the air in.

This is why the modern four valve engine is so different to the older two valve, in its tuning, but that is progress, and we have got to move with it or fall behind.

Edit P.S. The basic principle will be known to most and is very straight forward. A charge egnites in the cylinder and exits during the exhaust stroke as a lump of exhaust gas. It has weight and travelling down the exhaust pipe at speed results in a following low pressure wave. By having the inlet valve lopen before gthe exhaust valv e closes

Harvey.;)

I see that Harvey claims that there are differences in principle in regard to cylinder filling in respect of two and four valve engines and that this has to do with a strange change from "inertia" to more modern and sophisticated "sonic pressure waves". The claim is apparently, that the law of physics relies on valve numbers not valve area and that there is no reatonship between "sonic pressure Waves" and "inertia".
Differences which in modern times must be taken to account, when considering normal atmospheric induction, involve fuel injection and electronic engine management, not the BASICS of valve timing.

Those who do properly understand in a practical sense, think along the lines of simple "slugs of gas" regardless of the frequency/sound or speed of motion, even though this may not impress your "automotive engineer". The verbose text, once again designed to impress, may elude some but BS is clear to me.

I am concerned that one member has already been confused towards thinking that a different principle applies regarding valve timing, in respect of a pushrod engine and a twin cam four valve engine, or whatever. There is no difference, there has simply been improvements in the mechanics and as a result efficiency. What is more, not much is truly new in poppet valve engine design. Production methods have made possible what was previously too expenxsive.

Amplification and confirmation of the alleged facts, so blatantly stated, would make interesting reading.

Edit P.S.

The basic principle involved is quite straight forward and will be known to many. In very simple terms, when a charge in a cylinder is fired and exhausts as a lump of gas, it has weight and inertia. As it travels down the exhaust pipe a patch of low pressure is created behind it. The inlet valve is opened before the exhaust valve closes and this low pressure assists in "sucking" in the next charge. A similar action is carried through to the inlet tract, so that this also becomes part of the pipe which contains lumps of moving air or gas. The complete system becomes the subject of TUNING.

The distance between the pulses of gas results in pressure waves at a frequency directly related to engine RPM. These waves are most certainly "sonic" and there sound is music to many ears! Flat four, V6, V8, all obviously have their own song. There are other aspects involved as will be appreciated, e.g. expansion of the gas as it cools.

It does not take much brain power to relate the associated factors involved, e.g. obstructions in the form of passages and valves; valve timing; inlet tract length; exhaust design; number of cylinders; engine speed; etc; etc. Modifications can be made in many areas to alter the fundamental characteristics of the engine, with both positive and negative outcomes. These basic fundamentals have not changed over time, as has been claimed.

I have not gone to the trouble of compiling this extra hopefully simple explanation, in order to impress, but rather to prevent some from becoming confused by that previously posted.

[TomsSVX]

Since there has been great discussion and confusion as to what the best profile would be, I am going to stick with what is tried and true. I know from personal experience that the profile used in my old car was the cause of a significant gain. N/A with a standard transmission AWHP is about 170-180. Mods such as the stage 2v5 ECU included. Now the owner of my old car decided not to replace the stage2 ECU and is using a SAFCII which is a fuel controller. With this said, he dynoed my car at 191AWHP which is the most powerful EG33 to be dynoed to date. Even a standalone in an EG33 converted RS powered out only 185. Now if he had reinstalled the stage 2 software in my old car and dynoed it I am confident that he would have pulled 200+. Ths being said, I will be sticking with my old cam profile for the intake cams alone. I know it works and thats all I need to know. Harvey dropped the ball on answering my last Q so I will stick to what I know with no more dependencies

Tom

[Chiketkd]

Since there has been great discussion and confusion as to what the best profile would be, I am going to stick with what is tried and true. I know from personal experience that the profile used in my old car was the cause of a significant gain. N/A with a standard transmission AWHP is about 170-180. Mods such as the stage 2v5 ECU included. Now the owner of my old car decided not to replace the stage2 ECU and is using a SAFCII which is a fuel controller. With this said, he dynoed my car at 191AWHP which is the most powerful EG33 to be dynoed to date. Even a standalone in an EG33 converted RS powered out only 185. Now if he had reinstalled the stage 2 software in my old car and dynoed it I am confident that he would have pulled 200+. Ths being said, I will be sticking with my old cam profile for the intake cams alone. I know it works and thats all I need to know. Harvey dropped the ball on answering my last Q so I will stick to what I know with no more dependencies

Tom
That cam profile is definitely tried and true. My former 4EAT SVX dyno'd at 165awhp before the cams, and Myxalplyx dyno'd it at 175awhp w/o engine management.

[TomsSVX]

I never realize that there was close to a 20 WHP difference with a standard and auto trans. although I am sure your engine was much stronger than my j-yard motor I had in it. With the stage 2 and other mods I will probobly dyno the 6mt after the new cam install. I may even crack a single bottled run if I did indeed work out the kinks with the system

Tom

[Chiketkd]

I never realize that there was close to a 20 WHP difference with a standard and auto trans. although I am sure your engine was much stronger than my j-yard motor I had in it. With the stage 2 and other mods I will probobly dyno the 6mt after the new cam install. I may even crack a single bottled run if I did indeed work out the kinks with the system

Tom
Correct. The auto has at least a 30% drivetrain loss (could be even higher), while the 5mt is closer to 25%. As you start piling on 'effective' mods, those drivetrain losses really start to take their toll.

[Trevor]

Since there has been great discussion and confusion as to what the best profile would be, I am going to stick with what is tried and true. I know from personal experience that the profile used in my old car was the cause of a significant gain. N/A with a standard transmission AWHP is about 170-180. Mods such as the stage 2v5 ECU included. Now the owner of my old car decided not to replace the stage2 ECU and is using a SAFCII which is a fuel controller. With this said, he dynoed my car at 191AWHP which is the most powerful EG33 to be dynoed to date. Even a standalone in an EG33 converted RS powered out only 185. Now if he had reinstalled the stage 2 software in my old car and dynoed it I am confident that he would have pulled 200+. Ths being said, I will be sticking with my old cam profile for the intake cams alone. I know it works and thats all I need to know. Harvey dropped the ball on answering my last Q so I will stick to what I know with no more dependencies

Tom

Tom, you are dead right in sticking to and basing things on that which you know. When making mods to a production engine, estimate as best you can, test your decided option, learn from the result and move on from there. In other words, as you well know, it is all pretty much educated hit and miss. You show that you are making wise decissions.

The absolute object is to have fun. Cheers, Trevor.

[Trevor]

I have been thinking about what we can do with our cams. This thread is for those of you who know more about the technical points about them.

As of now we are able to weld and grind our intake cams to 8mm of lift with 240 degrees of duration. Stockers are 7mm of lift with 236 degrees of duration. Now this gives us a nice noticable improvement in power without sacrificing any drivability on the street.

I, however am looking to do something a little more radical with my next set. Since Delta Cams has provided me with a good price on cams I don't want to go anywhere else, but they are limited to pre-set profiles. That being said, lets talk about what else we can do.

I did a little research and I found that the most vital parts of designing a camshaft is the overlap... Increase the overlap and you will increase your upper rpm power but lose down low and have a "rougher" idle. This is what I am looking to do but not so far that it cannot be driven normally. Now say we stick with the 240 degrees of duration, what if we were to offset the cam teeth a little? I mean each cam sprocket contains 50 teeth which means each tooth is worth 7.2 degrees.

Oh, almost forgot. The exhaust cam profile is 8mm of lift with 244 degrees of duration.

With this information, what configuration would be optimal for a person looking to increase their high end power on a stock block?

Thanks for your help and please limit comments an questions to ones that are well educated

Tom

Tom, it is apparant that you know exactly where you are going and where you have come from.

Overlap is the important ingrediant. By grinding only the back of a cam, as an economically viable mod., lift is increased but the important factor is the associated extension of the opening time. Good to see that you have built up your cams with hard welding

There is no point in increasing the lift beyond a point whereby the open area of the valve exceeds the port area. A high lift increases mechanical stresses in a big way and involves further problems relative to valve bounce. Calculate the port area - OA area less the obstruction of the valve stem. The open valve effective area - The overall side surface area of a cylinder comprising diameter as above and hight as per valve lift.

You are not, on a basis of time and cost, able to experiment to the extent necessary to obtain an absolutely proven outcome, but with applied common sense you can be VERY close. Look up as many valve timing figures as you can, particularly performance related. In the back of your mind store all the characteristics and requirements of the cars involved. Compare, think, make a decission and when it gives results, as it will, rejoice with satisfaction, knowing you did it your way.

Believe me, alleged high tech. advice will not do more for you !

[Trevor]

Tom,

[For the first time in the years of using this service, (Special thanks to Chris and his helpers) contact has been delayed, but no moans from this part of downunder. As a result this post may be out in respect of time frame.]

This in effect a PPS to my previous post, so that you should also read it in conjunction. I appreciate that you started with this thread in the hope of obtaining positive confirmation that you had made a correct decision regarding your cam mods. and therefore make further comments, which I assure you, are the whole truth and NOT BS.

A few minutes ago I decided to have a look at the manufacturers figures in print. My immediate reaction was - increase the inlet opening and make inlet and exhaust near equal, which is the classic arrangement. My second thoughts back this up. For the fun of it I have not checked back in the thread, but I have a sneaking suspicion that you altered only the inlet cams and figure of eight was mentioned.

The resulting timing is still very mild, but the large valve area has the effect of increasing relative overlap as you will be aware. If we do both happen to think alike, two idiots must make a plus !

[SVXRide]

Trevor,
I've been talking with Tom and others on the Network about the cams in our engines, and it seems like we've arrived at the following:

1. The "welded&ground" intakes giving us 240 deg and 8mm lift do increase mid and upper rpm performance at the expense of a little low end (really not an issue with MT or 4.11/4.44 AT)

2. Looking for an "improved" profile for our exhaust cams has been a futile effort to date:mad:

3. Using our stock exhaust cam profile for "welded&ground" intakes is still open to discussion (i.e. additional 4 degress and I believe the ramps might be different than the profile Delta Cams is using for the 240 deg/8mm mod)

Thoughts?

-Bill

[SVXRide]

Since there has been great discussion and confusion as to what the best profile would be, I am going to stick with what is tried and true. I know from personal experience that the profile used in my old car was the cause of a significant gain. N/A with a standard transmission AWHP is about 170-180. Mods such as the stage 2v5 ECU included. Now the owner of my old car decided not to replace the stage2 ECU and is using a SAFCII which is a fuel controller. With this said, he dynoed my car at 191AWHP which is the most powerful EG33 to be dynoed to date. Even a standalone in an EG33 converted RS powered out only 185. Now if he had reinstalled the stage 2 software in my old car and dynoed it I am confident that he would have pulled 200+. Ths being said, I will be sticking with my old cam profile for the intake cams alone. I know it works and thats all I need to know. Harvey dropped the ball on answering my last Q so I will stick to what I know with no more dependencies

Tom

Tom,
Did you take a close look at the dyno plot for your old car? The AFR looks weirdly "flat" - it looks like it stays around 13.5:1 throughout the pull (never goes below 12:1)?
-Bill
p.s. then again, it may be another piece of info indicating that the EG33 really doesn't like to go as rich as what normal "tuning knowledge" would otherwise have us believe....

[Trevor]

Trevor,
I've been talking with Tom and others on the Network about the cams in our engines, and it seems like we've arrived at the following:

1. The "welded&ground" intakes giving us 240 deg and 8mm lift do increase mid and upper rpm performance at the expense of a little low end (really not an issue with MT or 4.11/4.44 AT)

2. Looking for an "improved" profile for our exhaust cams has been a futile effort to date:mad:

3. Using our stock exhaust cam profile for "welded&ground" intakes is still open to discussion (i.e. additional 4 degress and I believe the ramps might be different than the profile Delta Cams is using for the 240 deg/8mm mod)

Thoughts?

-Bill

Bill, some more thoughts to add to my previous brain children. More importantly, simply to mix with yours and your associates ideas.

Please advise the BTDC and ABDC figures so that I know where the inlet opening period sits in relation to TDC and I will set loose another storm.

Cam grinders can or can not be a good source of knowlege. Some are simply expert machinists. Others take a keen interest and sift results after getting feedback from customers. But at the risk of labouring a point, beware of the BS artist!

Best of luck with the project, Trevor *<)

[TomsSVX]

Sorry I haven't really been around the past couple days, had many things taking up my time and mostly work. I have a full 14hr day ahead of me but I have this week off. Trevor, there is a ton more info on the cams we selected in a thread Chiketkd had started. It was a quick how-to for a mild N/A build. He has all the specs for the cams in there. If I can find my data sheet from my last set I will post it. Sorry for the delay, just super busy

Tom

[TomsSVX]

Trevor, to keep you up to date, this is following info on what cams we have been using (Chike and Myself)

Stage 3:

The idea for upgrading the intake camshafts has been tossed around on this site for years. The specs I used were the brainchild of oab_au who based his theory off of the stock specs Wawazat measured a few years ago. Oab_au had helped his son modify his Z motor (which used similar internals to the EG33).

The stock specs are as follows:

Intake Cams: 7.0mm lift, 236 degrees duration
Exhaust Cams: 8.0mm lift, 244 degrees duration

I picked up a set of stock intake cams from TomsSVX around the end of summer and began exchanging PM's with Harvey...

Stock Cams
http://www.subaru-svx.net/photos/files/Chiketkd/27698.jpg

The ideal intake cam specs Harvey recommended for a 4EAT SVX are as follows:

8.0mm of lift, 240 degrees of duration

From here, I began speaking with several different camshaft grinders including Webcamshafts and Ram Performance. However, all roads led to www.deltacam.com in Tacoma, WA. Their sales guy Scott was very helpful and going back-n-forth with him and Harvey we settled on the following specs for the weld-n-grind on the intake cams (their machine wasn't set-up to do 240 degrees of duration):

8.0mm of lift, 247 degrees duration w/ the entire profile retarded by 7 degrees

The cost was $150.00 per cam excl/ shipping:

Modified Cams
http://www.subaru-svx.net/photos/files/Chiketkd/30395.jpg

SubaFreak and TomsSVX were very gracious to lend their assistance in the installation of these modifed cams, and on Saturday, November 5th I drove up to NJ to do the install.

We decided to pull my engine, even though it wasn't necessary, as it would give us extra working room on this install:

http://www.subaru-svx.net/photos/files/Chiketkd/31662.jpg

http://www.subaru-svx.net/photos/files/Chiketkd/31663.jpg

The valve covers were pulled, and while I replaced the seals, TomsSVX and SubaFreak installed the performance intake cams:

http://www.subaru-svx.net/photos/files/Chiketkd/31664.jpg

The Ride & Drive
As lift was increased by 1.0mm, there's more power throughout the rev band w/o a noticeable reduction in low-end power despite the slight increase in duration. My stall speed is still 2,500rpms and launches are still quick but w/o the excessive wheelspin and axle hop I experienced before (i.e. only slightly less torque down low).

As the rpms rise, the power comes on with a rush between 3,500-4,000rpms and from there it's a really quick blast to redline! :cool:

I can't say how much extra power these cams make as the stock MAF is maxed out between 240-250hp (per Mychailo's extensive testing with his wide-band and MAF voltage reader). I would make a conservative estimate of between 10-15hp, but to fully realize the performance potential of this upgrade the ECUTune Stage 2v5 w/ the Z32 MAF is a necessity!

-Chike

Tom

[Trevor]

As you I am sure appreciate, the thread is now so convoluted that I have had to more or less start from scratch in regard to my comments.

The stock specifications shown in the Subaru Manuals I have show :-

INTAKE - Opening 2* Before Top Dead Centre. Closing 54* After Bottom Dead Centre. Therefore duration, (not specified), = 236*)

EXHAUST - Opening 55* BBDC., Closing 9* ATDC. (Duration = 244*)

PATTERN in my language :- 54 - 2 - 9 - 55,

The overlap is therefore a very mild 11*

I have never seen valve timing expressed simply as an opening duration and can not see how this can indicate the true picture, A most important factor relates to where the timing sits in relation to piston travel expressed as TDC and BDC.

If the question had been originally been put to me, I would have said on a conservative basis, go for a mild say :- 55 - 9 - 9 - 55, as this requires altering only the inlet cams. This means an inlet duration of 244*. Harvey suggested 240*. which I would say would not have been worth the effort. Most important is that he does not specify a relationship with TDC.

It would appear that you have the inlet retarded by 7* which appears strange to me, although I agree that it is more usual to have more overlap on the exhaust side, particularly in respect of normal production engines. Possibly your idea also takes into account forced induction. Your advice in this regard could assist our discussion.

I gather from memory recorded back in the thread, that this 7* was achieved by shifting the camshaft gear engagement. If so it could be possible to revert to what I suggest by way of an experiment. Pleased that it is not me doing the hard yacker!!

My experience relates to more than one car I have altered for motor racing, but as I have pointed out before, your decisions have to be based on intuition. You are not able to experiment much, having cost in mind. I am simply putting forward my ideas for you to include within your thinking. In this connection, check my arithmetics.

Edit P.S. Taking into account the figures you have quoted, it would appear to me, that you are experimenting with what must be the most cost effective method of improving performance, relative to sporting requirements. Your efforts will I hope, be appreciated by others.

[TomsSVX]

So my initial thoughts about using our exhaust profiles may have been dead on. I was thinking of just using the same profile as the exhaust on the intakes. Leaving us with exactly what you are recommending. I will call Scott this week at Delta and make sure he still has the exhaust profile fom the cams Bill sent him. I will also see what kind of price we are looking at as it seemed every time I called, the price went up

Tom

[Trevor]

So my initial thoughts about using our exhaust profiles may have been dead on. I was thinking of just using the same profile as the exhaust on the intakes. Leaving us with exactly what you are recommending. I will call Scott this week at Delta and make sure he still has the exhaust profile fom the cams Bill sent him. I will also see what kind of price we are looking at as it seemed every time I called, the price went up

Tom

Please read all I have said and advise futher regarding the 7* advance. I am rather mixed up as to which, where and who involved here have forced induction. This is an important issue. The discussion must be confined to exact engine specifications and not SVX engines in general. In the case of forced induction, alterations to valve timing becomes less of an issue and not so worthwhile.

[SVXRide]

So my initial thoughts about using our exhaust profiles may have been dead on. I was thinking of just using the same profile as the exhaust on the intakes. Leaving us with exactly what you are recommending. I will call Scott this week at Delta and make sure he still has the exhaust profile fom the cams Bill sent him. I will also see what kind of price we are looking at as it seemed every time I called, the price went up

Tom

Tom,
Scott had better say he still has my exhaust cams;)
-Bill

[TomsSVX]

Trevor, the reason for the 7 degree pull on the cams has to do with how Delta Cams grinds theirs. They use profiles from camshafts they have already. In saying this, they used a nissan profile for us and did what they could to make it work with our cars. This is what I understand from what we had discussed when first looking to do these. If we use the SVX exhaust profile, I do not believe we will need to retard the profile since it is basically what we want from the get go

Tom

[Trevor]

Trevor, the reason for the 7 degree pull on the cams has to do with how Delta Cams grinds theirs. They use profiles from camshafts they have already. In saying this, they used a nissan profile for us and did what they could to make it work with our cars. This is what I understand from what we had discussed when first looking to do these. If we use the SVX exhaust profile, I do not believe we will need to retard the profile since it is basically what we want from the get go

Tom

Tom, I have again read the complete thread in an effort to sort things out. I am now assuming that in all respects the discussion is confined to normally aspirated engines.

I can not see how various valve timings can be discussed without BTDC and ATDC figures being quoted, rather than simply duration. It is vital that these figures are specified, being the essence of what is being considered here.

The cam grinders claim of retarding the complete period by seven degrees, if this is what is meant, appears strange. It would mean changing the position of the cam lobe which would mean one hell of a lot of welding and grinding. When you First mentioned this 7* I presumed the cam shafts had been moved via the gears. You mentioned the possibility of a one tooth and 7.28* adjustment. Have the grinders possibly intended that you move things one tooth and if so why? In fact how and from where did this idea of retarding the overall duration come about ?

If the lobes are in fact retarded by 7*, as I think I mentioned previously, you could advance the cam by one tooth by way of an experiment and I would be surprised if there were not an improvement.

Have you actually taken measurements with the re ground cams in place ? Before making assumptions you should check on exactly what you have received and paid for. N.B. measure in relation to TDC. You are basing your future decisions on what you have tested. You MUST be certain of the actual figures and not simply accept the grinders word.

[TomsSVX]

I have measured the new cams in comparison to the old. The do increase lift by 1mm. didn't measure the duration, i do not have the machinery to do so. i reiterate that the i believe th 7* retard was just us being about to use that profile and keep our peaks at the apropriate relation to TDC

Tom

[Trevor]

I have measured the new cams in comparison to the old. The do increase lift by 1mm. didn't measure the duration, i do not have the machinery to do so. i reiterate that the i believe th 7* retard was just us being about to use that profile and keep our peaks at the apropriate relation to TDC

Tom

Tom, machinery is not required. All I have used, like all those I know, is a home made protractor in the form of a large cardboard disk, attached to the crankshaft pulley and some kind of jerry rigged fixed pointer. Awkward to do on the SVX like everything else. (To be honest I don't know how you guys have the patience to work on the thing.) A mirror will help and you can make pencil marks, to be read after the protractor is removed. You will of course have to remove cam covers in order to view valve opening and closing and full lift points, which is another chore. A check on two valves should provide adequate confirmation.

You can also work off off the cam gear, taking the ratio into account, but have to be able to directly associate TDC.

Frankly, you are completely in the dark, unless you are sure of what you have by taking your own measurements.

QUOTE :- "i reiterate that the i believe th 7* retard was just us being about to use that profile and keep our peaks at the apropriate relation to TDC".

The very point. You seem just not sure and MUST find out. To me 7* retard means shifting the cam lobe position by 7* and therefore the complete inlet period. This in my opinion would be bad news.

Cheers, Trevor

[TomsSVX]

I have a spare motor to work with... doesn't have to be done inside the car. Also, like I said I believe the lobe center was moved from the profile's initial layout to be complacent with our application. I need to find my spec sheet from Delta cam. Hopefully Chike or (those who we do not speak of mods) still has their sheets. I will go look for it now

Tom

[Trevor]

I have a spare motor to work with... doesn't have to be done inside the car. Also, like I said I believe the lobe center was moved from the profile's initial layout to be complacent with our application. I need to find my spec sheet from Delta cam. Hopefully Chike or (those who we do not speak of mods) still has their sheets. I will go look for it now

Tom

With a bench motor it will be a piece of cake and you should find it an interesting exercise.

At the risk of telling you how to suck eggs - you will have to take into account the hydraulic lifters unless you have replaced them. I would guess that you can accept that when the cam solidly comes against the lifter, you can regard this as the lift point and vis-a-vis. In any event provided you are consistant any error should be obvious, particular if you do the exhaust cams, by way of comparison with the standard figures.

The results will be of real interest to me and I am sure many others.

Best of luck with it, Trevor.

[Phast SVX]

So delta is increasing the lift? Im more looking to reduce overlap while keeping lift alone. I think the high turbine inlet pressure leaves something to be desired, and im pretty sure im over the 2:1 rule of thumb but have not had the car on the dyno to check it out.

Also, increased tensile pressure on the stock springs is a concern, and thus my chance of float since im boosted. Are they flexible on what they will do, or do these have to be in orders?
phil

[Trevor]

So delta is increasing the lift? Im more looking to reduce overlap while keeping lift alone. I think the high turbine inlet pressure leaves something to be desired, and im pretty sure im over the 2:1 rule of thumb but have not had the car on the dyno to check it out.

Also, increased tensile pressure on the stock springs is a concern, and thus my chance of float since im boosted. Are they flexible on what they will do, or do these have to be in orders?
phil

If you wish to reduce overlap, this can be achieved by simply grinding material off the cams and you will not be involved in any increased lift.

Edit P.S. You could also try moving the cam gear one tooth, so as to delay the inlet opening by approximately seven degrees. Check back in the thread so that you have the complete picture.

[Phast SVX]

Guess i should have read the entire thread before posting.... :o


...The overlap is therefore a very mild 11* ....



Wow 11*, that definetly counts me out of this conversation. definetly not high enough to cuase an excessivly fouled charge, as long as my turbine/AR is large enough. Guess ill just have to bite the bullet and go with a larger hot side to lower TIP. I had always thought that high overlap was part of the reason subaru had designed the intertia resonance system to regain some of the low end power. Learn something everyday

[Trevor]

Guess i should have read the entire thread before posting.... :o

Wow 11*, that definetly counts me out of this conversation. definetly not high enough to cuase an excessivly fouled charge, as long as my turbine/AR is large enough. Guess ill just have to bite the bullet and go with a larger hot side to lower TIP. I had always thought that high overlap was part of the reason subaru had designed the intertia resonance system to regain some of the low end power. Learn something everyday

As a matter of interest, I have an old 1971 Subaru FF1 sports sedan which I purchased new to drive in a production championship series of circuit races. It won hands down and I regard it as the best engineered car I have owned (there have been many) and therefore I still have it and drive it often. The engine is perfectly tractable and my wife ran the kids about in it for several years. Things start to happen at about 3,750 RPM and the valves bounce at 7,300 RPM. (Two valve push rod engine.)

Valve timing :- 76-40-40-76. i.e. 80 degree overlap. (i.e.Intake 76* BTDC, and 40* ABDC)

The standard model has :- 64-24-18-70

[TomsSVX]

maybe it would be best for someone that has a head off a motor to do the measurements. This way the lifter can be taken into account? What would Bill think about it measuring my old heads?? Bill??

Tom,

[Chiketkd]

Hopefully Chike or (those who we do not speak of mods) still has their sheets. I will go look for it now
I never saw a spec sheet when Delta Cam returned my finished camshafts. If it was included, I may have thrown it out with the packaging... :o

[SVXRide]

I still have the DeltaCams spec sheet (in the box with the cams)...
I will have my spare engine (thanks Dave/Ben) on an engine stand this week (I hope!). I've still got Harvey's instruction for taking measurements, so I'll just have to install one of the DeltaCams in the engine and have at it. This might take me a couple of weeks, as things are getting very busy the rest of this month.
-Bill

[Trevor]

maybe it would be best for someone that has a head off a motor to do the measurements. This way the lifter can be taken into account? What would Bill think about it measuring my old heads?? Bill??

Tom,

Tom,

The measurements should not be taken with the head off. All must be in place and exactly operational as normal. I have advised the correct way to do it. The actual relationship with crankshaft position must be positively varified when all is set up as running. Lift is a separate aspect in the equation.

I see that Harvey's instructions have been suggested. In the light of his previous posts, it would be interesting to see those instructions. If decissions are going to be based on measurements made using that which could be suspect, I will have no further confidence in the project.

Sincerely, Trevor.

[SVXRide]

Okay, here you go....


http://www.subaru-svx.net/photos/files/SVXRide/35887.jpg


-Bill (yeah, I really don't have these cams in my engine....honest!)

[SVXRide]

Trevor,
In response to your request, here's what Harvey PM'ed me:

Checking valve timing, and lobe center.

This is the method I would use to check the valve timing and find the inlet lobe center.
I use a plastic degree wheel stuck, to the harmonic balancer, with double sided tape, with the TDC marks aligned. Set up a wire pointer on one of the bolts on the front of the engine, so that it is in line with the 0 degrees on the degree disc.
Zeroing the degree disc to the crank.
Set up a dial indicator through the plug hole, and zero it while the piston is at TDC. Rotate the engine( always turning the engine forwards,NEVER TURN IT BACKWARDS) till the dial ind. shows the piston has dropped 0.050". read the degrees the crank has turned pass TDC. Say it is 12*. Turn the engine over till the piston is 0.050" from the TDC. Read the degrees, say it is 8*, that means that the wire pointer is too far to the 12* side, so we half the difference 4*, and move the wire pointer 2* to the 8* side, so that the pointer is aligned with 10* BTDC. This zeros the degree wheel to the crank, it will now read the same 10* at 0.050" before and after TDC.

Measuring the valve timing.
Set up the dial indicator on the top of the valve follower, zero the needle. There is two different ways to show duration figures, the US way is to start the measurement at 0.050" lift, and end 0.050" from the fully closed position. The other which everyone else uses, is from seat to seat. Turn the engine till the dial shows the first movement, of the valve opening, read off the degrees BTDC. (This is the start of the seat to seat duration.) Keep turning till the follower has moved 0.050", read off the degrees, (this is the start of the US duration). Turn the engine over till the valve is 0.050" from closing, (US closing point), keep turning till the valve has stopped. (end of the s to s duration)

The book quotes the timing to be ;Inlet 2* BTDC, 54* ABDC 236* Duration. Exhaust 55* BBDC, 9* ATDC. 244* Duration.

Finding the lobe center.
Turn the engine till the valve is fully open, zero the dial needle. Turn the engine till the dial shows 0.050" from fully open, read the degrees, keep turning till the valve has closed 0.050", read the degrees. Add the two degree readings together divide by two. This is the inlet lobe center. Worked out from the timing in the book, this is 116* ATDC.

If you can find what the factory lobe center is, and what the new cam duration and lobe center is. We will know where we stand.

-Bill (aka "Fountain of Cam Knowledge":D )

[Trevor]

Trevor,
In response to your request, here's what Harvey PM'ed me:

Checking valve timing, and lobe center.

This is the method I would use to check the valve timing and find the inlet lobe center.
I use a plastic degree wheel stuck, to the harmonic balancer, with double sided tape, with the TDC marks aligned. Set up a wire pointer on one of the bolts on the front of the engine, so that it is in line with the 0 degrees on the degree disc.
Zeroing the degree disc to the crank.
-----------------------------------

AGREED, Provided "Zeroing the disc to the crank" clearly means at TDC.

The following in appears to be made up from words lifted from a US publication, which is fair enough.
----------------------------------

Set up a dial indicator through the plug hole, and zero it while the piston is at TDC. Rotate the engine( always turning the engine forwards,NEVER TURN IT BACKWARDS) till the dial ind. shows the piston has dropped 0.050". read the degrees the crank has turned pass TDC. Say it is 12*. Turn the engine over till the piston is 0.050" from the TDC. Read the degrees, say it is 8*, that means that the wire pointer is too far to the 12* side, so we half the difference 4*, and move the wire pointer 2* to the 8* side, so that the pointer is aligned with 10* BTDC. This zeros the degree wheel to the crank, it will now read the same 10* at 0.050" before and after TDC.
----------------------------------

AGREED AS A WAY OF CONFIRMING TDC, if this can not be established from reliable marks. This method can be simplified by using a probe and educated feel, to establish that the piston is rockiong over TDC, if a dial gauge is not available. The "never turn the engine backwards", suggests the possibility of excessive big end clearance, which should become obvious while rocking the crank shaft. However this instruction should be carried forward regarding cam measurements, as here tolerances in the camshaft drive must be taken into account.
--------------------------------

Measuring the valve timing.
Set up the dial indicator on the top of the valve follower, zero the needle. There is two different ways to show duration figures, the US way is to start the measurement at 0.050" lift, and end 0.050" from the fully closed position. The other which everyone else uses, is from seat to seat. Turn the engine till the dial shows the first movement, of the valve opening, read off the degrees BTDC. (This is the start of the seat to seat duration.) Keep turning till the follower has moved 0.050", read off the degrees, (this is the start of the US duration). Turn the engine over till the valve is 0.050" from closing, (US closing point), keep turning till the valve has stopped. (end of the s to s duration)

The book quotes the timing to be ;Inlet 2* BTDC, 54* ABDC 236* Duration. Exhaust 55* BBDC, 9* ATDC. 244* Duration.
---------------------------

AGREED.

Finding the lobe center.
Turn the engine till the valve is fully open, zero the dial needle. Turn the engine till the dial shows 0.050" from fully open, read the degrees, keep turning till the valve has closed 0.050", read the degrees. Add the two degree readings together divide by two. This is the inlet lobe center.
-------------------------------

READING THE PROTRACTOR when the valve is established to be at full lift will give the exact lobe centre in practical terms, without any calculations. But do not rock the shaft without thought, unless absolutely no play is present in the cam drive.

Although it is desirable to use a dial gauge in making all of these measurements, the eye and feel can be very accurate if used sensibly .
------------------------------

If you can find what the factory lobe center is, and what the new cam duration and lobe center is. We will know where we stand.
-----------------------------
AGREED --- N.B. we already know the factory lobe centre if we accept published figure, but a check would be worthwhile and could also varify other mearsurement methods have been reliable

-Bill (aka "Fountain of Cam Knowledge":D )

Please be sure that my intention is not to be smart by adding the above comments and that most of all I simply wish to assist.

[Trevor]

Okay, here you go....

-Bill (yeah, I really don't have these cams in my engine....honest!)

Regarding the timing sheets -- please confim that the first sheet covers the stock cams and the second the modified cams as were supplied, or advise if otherwise.

Thanks, Trevor.

[SVXRide]

Regarding the timing sheets -- please confim that the first sheet covers the stock cams and the second the modified cams as were supplied, or advise if otherwise.

Thanks, Trevor.


Trevor,
The top part of the sheet is supposed to be the specs of the stock intake cams, the bottom the "modified" intake cams.
-Bill

[SVXRide]

Trevor,

Could you take a look at this thread to see what you think, relative to how it fits in with the info in this thread?

http://www.subaru-svx.net/forum/showthread.php?t=31125&highlight=Cam+Lobes

-Bill

[Trevor]

Trevor,

Could you take a look at this thread to see what you think, relative to how it fits in with the info in this thread?

http://www.subaru-svx.net/forum/showthread.php?t=31125&highlight=Cam+Lobes

-Bill

A good deal of investigation appears to have taken place but I can not understand why all of the measurements and specifications do not relate the effective valve openings to crankshaft position i.e. BTDC and ATDC. The duration alone does not give the required picture. Until this is established all is in the dark.

There appears to have been some emphasis towards valve lift, although this may have been so as to be able to accommodate existing cam profiles. There is also reference to reducing valve seat width which will effect seat wear. The SVX has a very large valve area and therefore both of these modifications are not as relevant as they were before the four valve era. Increased valve lift carries with it disadvantages in respect of greatly increased mechanical loading. In both of these areas anticipated improvement must be carefully weighed against the negative effects. My understanding is that you are not intent on building race engines, which will be pulled down and refreshed at short intervals.

Based on the limited information you had on hand it would appear that you went with the right lobe shape as a starter, but still have not established where this sits in relation to TDC, which is a VITAL issue. The very essence of valve timing revolves around piston travel and position, relative to valve position and I can not understand how this so far appears have been ignored.

I note that Harvey has brought aspects of the inlet tract into the discussion, which does no more than confuse the issue. I agree that this and valve timing are related, but each is independent of the other and with due consideration can be adjusted individually.

[Trevor]

Trevor,
The top part of the sheet is supposed to be the specs of the stock intake cams, the bottom the "modified" intake cams.
-Bill

Bill , I can not relate the figures recorded for the stock cams, with the figures published by Subaru. e.g.

Intake opening: -27 BTDC (Very strange figure). Subaru's figure: 2* BTDC (Logical).

Intake closing; 33.8 ABDC. Subaru's figure: 54 ABDC.

Duration: 186.9 crank degrees. Subauru's figure: (Calculated) 236*.

Lobe centre: 120.6* ATDC. Subaru's figure: (Calculated) 120*).
N.B. This figure is within tolerance.

How can one have confidence in the figures for the modified cams? Your own measurements become even more essential!

Cheers, Trevor.

[Trevor]

Bill , I can not relate the figures recorded for the stock cams, with the figures published by Subaru. e.g.

Intake opening: -27 BTDC (Very strange figure). Subaru's figure: 2* BTDC (Logical).

Intake closing; 33.8 ABDC. Subaru's figure: 54 ABDC.

Duration: 186.9 crank degrees. Subauru's figure: (Calculated) 236*.

Lobe centre: 120.6* ATDC. Subaru's figure: (Calculated) 120*).
N.B. This figure is within tolerance.

How can one have confidence in the figures for the modified cams? Your own measurements become even more essential!

Cheers, Trevor.

After giving the matter further thought overnight I think I may have come up with an answer regarding the variations in figures. I think measurements as above, have been taken using a point contact with the cam lobe rather than a flat surface as applies in respect of the engine. The valves in SVX engine obviously are operated by contact with flat followers rather than sharply radiussed rockers and this is a very important aspect to be taken into account. With this in mind the figure I found to be strange i.e. -27, could mean, point 27 and I will look into all this again.

This brings up the important point that when profiles as such, are compared one against the other, the associated mechanical arrangements must be taken into account. It is therefore best to use the engine manufactures valve timing figures.

All this probably came to mind as a result of early experience. Over Fifty years ago, when I built my first car to go motor racing on a very, very low budget, I studied the effects of valve timing and came up with an idea based on the preceding facts. The engine I was using had a single over head cam operating inclined valves, one each side, via rockers having contact surfaces with a sharp radius. I built these up with hard welding, ground them flat and the result will be obvious. Strangely I have never read of any one else using this cheap but effective method.

[Trevor]

After further thought and calculations, it would appear the the figures prefixed with "-" i.e. a negative sign, should be taken as indicating in effect ATDC, not BTDC. If this, as well as point contact measurement is accepted, things fall more or less into place. Please read this in conjuction with my previous posts.

One can of worms, to be sorted out only by means of actual readings in respect of the modified cams. These figures I await with great interest. :confused:

[oab_au]

The figures quoted in Bills slips are US timing, taken at 0.050" lift as I stated in the PM that I sent him, and has been posted.

Harvey.;)

[Trevor]

The figures quoted in Bills slips are US timing, taken at 0.050" lift as I stated in the PM that I sent him, and has been posted.

Harvey.;)

If that is so, you will be able to correlate this fact with the figures quoted in the sheets and Subaru's specifications and exactly explain the reason for a discrepancy in numerical terms. These figures will be awaited with interest.

I can see why a constant degree of lift was used in the instructions which you provided, so as to elliminate possible error through backlash, but I had presumed that these instructions were specifically intended to establish only the lobe centre.

Can you please advise how what you state, can be confirmed as a universal system used in US. This is certainly very important in relation to the exercise underway. It would appear to be a very difficult system to directly convert to that which is normal, considering the variables involved. Can you suggest a conversion factor?

[oab_au]

If that is so, you will be able to correlate this fact with the figures quoted in the sheets and Subaru's specifications and exactly explain the reason for a discrepancy in numerical terms. These figures will be awaited with interest.

I can see why a constant degree of lift was used in the instructions which you provided, so as to elliminate possible error through backlash, but I had presumed that these instructions were specifically intended to establish only the lobe centre.

Can you please advise how what you state, can be confirmed as a universal system used in US. This is certainly very important in relation to the exercise underway. It would appear to be a very difficult system to directly convert to that which is normal, considering the variables involved. Can you suggest a conversion factor?

1. You just have to take both sets of figures as fact, for the two measurements. Subaru's are "seat to seat", the US timings are at .050" lift.

2. If you are referring to the way the lobe center is found. It is not to eliminate backlash in the drive train, but the lack of valve movement over the fully open position, that may take more than 15* degrees, we need it more accurate than that.

3. I don't know if it is universal,. but you will have trouble finding a seat to seat measurement in any cam grinders settings. The small ends of the cam opening, don't have a big effect on the results, it is mainly to do with the ramps that open and close the valve. As there are many different types of followers, direct acting flat solid or hydraulic and roller, symmetrical profiles. And the asymmetrical profile for lever finger, rocker types of followers.
So they just leave them out and use the business end of the cam, from 0.050" on.

Harvey.;)

[Trevor]

1. You just have to take both sets of figures as fact, for the two measurements. Subaru's are "seat to seat", the US timings are at .050" lift.


******** I do not have to take anything as fact, if it is not true. Please give me the figures as requested.

******** "US timings". If there is such a thing as US timing, this needs to known as it becomes a vital and necessary contingency.


2. If you are referring to the way the lobe center is found. It is not to eliminate backlash in the drive train, but the lack of valve movement over the fully open position, that may take more than 15* degrees, we need it more accurate than that.


*******I am not referring to any such event! Your words have no meaning. What has the alleged - "the lack of valve movement over the fully open position, that may take more than 15* degrees" - to do with the issue of timing measurements taken from the start and end of the lift.
What is more you are stating that the cams are in fact flat over 15 degrees at full lift, or nealy flat or whatever. Is this some sort of claim that full lift can not be easily established at better than 7.5 degrees? In any event again what has this got to do with an elapsed period from the start to the end of lift.

3. I don't know if it is universal, but you will have trouble finding a seat to seat measurement in any cam grinders settings. The small ends of the cam opening, don't have a big effect on the results, it is mainly to do with the ramps that open and close the valve. As there are many different types of followers, direct acting flat solid or hydraulic and roller, symmetrical profiles. And the asymmetrical profile for lever finger, rocker types of followers. So they just leave them out and use the business end of the cam, from 0.050" on.


****** Your original statement was definitive. There is a universally accepted method of measuring valve timing and I, others and Subaru use it. I note that you have learned a little from this thread, relative to cam followers and their effect.

It is interesting, that you now confirm exacly what I have suggested, i.e. that measurements have been taken by the grinders at a point of contact. This being the essence of what I have suggested as a reason for the discrepancies. Your theory relies on the existance of a special US form of measurement.

N.B. Is there or is there not a US system involving a 0.050" included measurement, those involved with this thread, need to know. Is such a standard system in use, recorded, if so where?


Your reply will be awaited with interest and concern in respect of others involved in this issue. *<)

P. S. Harvey, there are now accurate answers posted. I appologies for my rather curt message, but I continue to not agree with the logic and some statements in your proposal. What has now been properly set out indicates that my theory although logical was apparently wrong and I accept that yours was basically correct.

[dynomatt]

I'm new...but have some general experience with cams.

In my experience aftermarket cams are often sold with either an advertised duration or a 0.050" duration.

The intent is that at 0.050" (remember that's 1.27mm lift) it's taken up most of the slack in the valve train, and is a repeatable indication of the cams duration.

Advertised duration varies wildly based on things like hydraulic pump-up effects etc and is unable to be reverse engineered to a 0.050" result.

www.tighecams.com.au who are cam grinders of repute in Australia utilise the 0.050" system, as do others...it's not limited to the US.

And Trevor, all your comments about how the duration is related to TDC positions etc, in my experience, doesn't have much relevance. Lobe centrelines or angles or LCA or whatever you want to call them, become the important issue....and they can be set (assuming vernier wheels) however you want. That's where you can also effect overlap as Tom mentioned.

The other thing that's been bugging me is the cam suggested earlier, with a duration of 247 degrees, and then it being suggested to be retarded 7 degrees...I don't think this will have the desired effect. Duration is a function of the lobe profile, and retarding the cam timing doesn't alter that...it just means that the cam will be retarded with the associated losses.

Having just been through a fair bit of grief to do with cam selection on a recent rally car project, I'm comfortable with what I'm saying.

This page (http://www.billzilla.org/4agmods.htm) by example has some information regarding 4 valve per cylinder performance mods specifically for the 4AGE. Obviously there are marked differences between the EG33 and the 4AGE, but some of the core theories can be applied. He talks about common 4 valve twin cams having about a 240 degree (seat to seat, not 0.050") duration which is close to the EG33. He then suggests that going to something like a 264 degree (seat to seat) starts to be the limit of the standard ECU. Having read elsewhere on this forum, I suspect MAF's become a problem before that. Combine that with the guy who built the WRX with the stock EG33 and ony an aftermarket ECU, which yielded 212ATWHP, I suspect the standard EFI system is a limiter.

Based on that, my theory is that I suspect EG33's could absorb more than 247 degrees...and maybe more like 260 which is the kind of duration for Tom's originally proposed "little more radical" cams.

If I had a spare complete head, I would be happy to get another set of cam measurements to get the standard profile (if only to support prior work), but more importantly, I have access to a flow bench, and could continue Bill and VTSuby's work in order to start to more accurately realise the potential of this motor.

Matt

[Trevor]

Greetings Matt,

You certainly appear to be an authority on cams and you are a welcome addition to the thread. In fact I would accept that I am no longer required.

I have never seen figures set out as has been described and accept your superior knowledge and have been wrong in doubting Harvey, even though his evidence is far from convincing. I fully understand the reason for including the 0.050" figure but this does make it very difficult to relate specifications.

You have provided the required figure I needed to enable the relationship to be ascertained i.e. 0.050" equals 1.27 mm lift. This is the exact information required and had it been known and provided there need be no arguement.
With this on hand it is possible to put figures together. It would appear that my assumption that the figure shown as BTDC is in fact ATDC, the negative sign indicating this.

I gather what you are saying is that the lift and closing ramps are probably of a different shape and hence the lobe need not be centred. Please confirm. Even so there must be a relationship established/existing between piston position and valve timing. We appear to be simply at cross purposes in the way we may be describing this issue. However I am sure that I clearly made lobe centre lines the important point as you do.

We are in accord regarding the possible ammended timing figures particularly the suggested 7* retard figure which I could not relate to. What is more I agree 260* duration should not be out of the way.

Your further comments will be appreciated by all.

Cheers, Trevor.

[dynomatt]

No flattery required...but thankyou.

I'm unsure whether lift and closing ramp shapes differ...I would suspect not. In fact most cam graphs I've seen show a perfect arc...suggesting that both ramp shapes are identical. I expect it may also be a machining issue.

A relationship does exist with cams and piston position. It is referred to as the lobe centre angle, centre line etc. This is always quoted as a degree of BTDC and ATDC eg 110-115 degrees. For example, for inlet cams, 110 degrees AFTER TDC is the point that the inlet valve is fully open. Adjustment of these centre lines changes things like overlap etc. Longer duration cams usually mean the centre angles are reduced...but then other problems arise, like idle etc.

My reading of the site says that this is usually where the "interference engine" issue arises...but you'll notice that the valve is fully extended when the piston is 110 degrees after TDC...hence it's 2/3 the way down the bore (or 50mm when we are talking about 8-10mm lift ;)).

Where I am curious is that given the exhaust cam drives the inlet cam in a geared arrangement, just how much adjustability do we have to select optimum centre angles assuming a vernier wheel is fitted...I suspect not much. A vernier cam wheel will only allow mutual advancing/retarding with both cams acting as a unit...rather than individual adustments which is optimum. This could be a limiting factor but I suspect if it is, it would only be a minor one.

[oab_au]

There are two forms of "lobe center" talked about. One is the angle formed between the inlet and exhaust cam lobes, and the one that I use, is the inlet valve fully open position, in relation to the crankshaft position.
This has more meaning that just the relationship of the inlet and exhaust lobes, to each other, which is just the result of positioning the two individual cam positions.

The main objective of timing the inlet cam is to match the maximum open position of the inlet valve to the maximum air speed in the inlet tract. The fully open position of the inlet valve is fixed by the gearing. The maximum air speed in the inlet tract varies with the engine speed. The maximum piston speed is achieved at about 85* ATDC. At say 1000 rpm the maximum air speed will follow the piston, but as the engine speed increases the maximum air speed lags behind the piston speed. So that at say, 5000 rpm the maximum piston speed is at 85* ATDC, but the maximum air speed will not happen till say 115* ATDC.

So to get the engine to develop maximum torque at 5000 rpm we have to have the inlet valve fully open, at 115*to allow the maximum air speed to match the fully open valve position. As we change the engine speed for maximum torque, we have to change the inlet lobe center to bring the two to the same speed. Move the torque peak up the rev range requires the lobe center to be retarded. Bring the torque down the range needs the lobe center to be advanced.

The duration used, is a function of the engine speed that the maximum torque is required. The higher the engine speed, the longer the duration needed to allow the cylinder to fill.

This outlines the 3 stages that I purposed, some time ago.
http://www.subaru-svx.net/forum/showthread.php?t=29048&page=11&highlight=stages post 164.

Thanks for joining the thread Matt.

Harvey.;)

[SVXRide]

Matt,
Ditto what Harvey and Trevor said regarding your joining the thread!:cool:
What I believe I'm reading now is that the 7 degree of "retard" used when installing the DeltaCams in Chike's old car, Tom's old car, and ShotgunSlade's car is, most likely, reducing the Hp increase possible with these cams?
Thanks.
-Bill

[dynomatt]

I'm not sure...I believe that advancing the cam generally improves the low end torque. Within limits obviously.

The only way you can tell if it's doing anything is to dyno it back to back.

So much of this stuff is trial and error.

Matt

[dynomatt]

Oh and Bill...what would help is more flow information!!!

[oab_au]

Matt,
Ditto what Harvey and Trevor said regarding your joining the thread!:cool:
What I believe I'm reading now is that the 7 degree of "retard" used when installing the DeltaCams in Chike's old car, Tom's old car, and ShotgunSlade's car is, most likely, reducing the Hp increase possible with these cams?
Thanks.
-Bill
Yes Bill, I explained that back in Chikes thread here.
http://www.subaru-svx.net/forum/showpost.php?p=357578&postcount=97
Harvey.;)

[Trevor]

An important object of this exercise, now well off track, was to analyze the differences between the cam grinders figures and Subaru's specifications. At long last here are the figures :-

Subaru's figures relating to the standard cam are shown as, SS

Grinders figures relating to the standard cam are shown as, SG

Grinders figures relating to the modified cam are shown as, MG

All figures should be read as degrees of angle.


Relating the figures SS and SG:-

Duration: SS 180 + 2 + 54 = 236. SG 180 - 27 + 33.8 = 186.8.

Overall Difference = 49.2. At each end of the cam, 24.6

Therefore 24.6 is the estimated rotation relative to 0.05" valve travel.

Inlet, SG 27 ATDC - 24.6 = 2.4 SS 2 BTDC and error = 4.4

Exhaust, SG 33.8 ABDC + 24.6 = 58.4 SS 54 and error = 4.4

Corrected 0.05 travel figure = 24.6 + 4.4 = 29

Comparison between SG and SS figures:-

Opening SG BTDC (-27) Correction 29 = 2, SS = 2 ( No change)

Closing SG ABDC 33.8 Correction 29 = 62.8, SS = 54 ( 8.8 increase)

N.B. The correction figure has been calculated on absolute values and it is probable that Subaru's figures provide for some slight valve/lobe clearance, in which case the figure of 29 could be accepted as say 27.5. This would bring the figure of 8.8 increase, down to 7.3 which is near the obscure figure mentioned several times in the thread.

Relating the figures SG and MG:-

Duration: SG 186.9, MG 180 - 23.4 + 36.2 = 192.8, Increase = 5.9 = 3.2 %

Relating the figures MG and SS:-

Duration: MG 192.8 + 29 + 29 = 250.8, SS 236, Increase = 14.8 = 6.27%

The end result of the cam grind, as anticipated, indicates only a very limited degree of change which appears hardly worth the effort and expense.

The increase in lift shown is .784 mm which amounts to 11% increase.

Edit:- The actual effective increase in breathing can be shown as less than 3%, due to the limited time when the valve is fully open. However there could be some additional very limited advantage, due to a slight increase in the terminal speed of the gas flow.

Going for the reasonable maximum and to make a real difference, I will stick my neck out and suggest:-

Based on Grinders Measurements:-

Duration: 202, Opening 24, ATDC, Closing 46 ABDC.

Edit. I think you could go as far as say:- 210, 20, 50.

Based on Usual Measurements:-

Duration; 260, Opening 5, BTDC, Closing 75 ABDC.

Edit :- 268, 9, 79

Are there any takers ? :D

[shotgunslade]

Actually, I believe my cams were ground to Harvey's suggestion for the 5MT with 3.9 ratio

"8mm lift, 247* duration and 118* lobe centering, per Harvey's recommendation for use with 3.9 5MT."

[SilverSpear]

Actually, I believe my cams were ground to Harvey's suggestion for the 5MT with 3.9 ratio

"8mm lift, 247* duration and 118* lobe centering, per Harvey's recommendation for use with 3.9 5MT."

Where he recommended those specs? :eek:

[shotgunslade]

If my duration is 247 degrees and the lobe centering is 118* ATDC ,then opening would begin at 5.5* BTDC and closing would be at 62.5* ABDC, assuming that the opening and closing cam profiles are symmetrical. If this is correct, then I may be beginning to understand the geometry of this issue.

[SVXRide]

Oh and Bill...what would help is more flow information!!!

Ouch:rolleyes: :D

I've got to get the right bolts (yes, M10-1.5 bolts are NOT the right bolts to put an EG33 up on an engine stand:mad: ....M10-1.25 on the way...) so I can get my spare engine on the stand and pull the heads off and get moving on them. The heads I already have will probably be sliced up...
-Bill

[Trevor]

Actually, I believe my cams were ground to Harvey's suggestion for the 5MT with 3.9 ratio

"8mm lift, 247* duration and 118* lobe centering, per Harvey's recommendation for use with 3.9 5MT."

As I understand it all of the cams which have been ground are in accordance with the grinders specs as posted in this thread. My figures are based on these. If you doubt their accuracy please check them out and advise. If there are errors these should be corrected as a matter of urgency.

[Trevor]

If my duration is 247 degrees and the lobe centering is 118* ATDC ,then opening would begin at 5.5* BTDC and closing would be at 62.5* ABDC, assuming that the opening and closing cam profiles are symmetrical. If this is correct, then I may be beginning to understand the geometry of this issue.

It would appear that you are using the usually quoted figure for duration and the grinders figures for lobe centre. This has been a problem through out and is the very reason I have gone to considerable trouble in producing figures which clarify the position. I leave it to you to use them.

BTW as far as I can see Harvey has not produced figures which exactly indicate positions relative to TDC/BDC. Could someone please point out exacly where these can be found. There does appear to be absolute confusion regarding these figures.

[Trevor]

Ouch:rolleyes: :D

I've got to get the right bolts (yes, M10-1.5 bolts are NOT the right bolts to put an EG33 up on an engine stand:mad: ....M10-1.25 on the way...) so I can get my spare engine on the stand and pull the heads off and get moving on them. The heads I already have will probably be sliced up...
-Bill

Greetings Bill,

I am now confident that you can accept the grinders figures as gospel. Everything adds up, as i have shown. It now remains for you guys to decide on your next move. Over ---

P.S. N.B. But ---- What was/is the situation in respect of the 7* retard, which was part of Harvey's specs. Were the cams in fact fitted one tooth retarded ??

Quote 15/05/06 -- "The ideal intake cam specs Harvey recommended for a 4EAT SVX are as follows: 8.0mm of lift, 240 degrees of duration
We settled on the following specs for the weld-n-grind on the intake cams (their machine wasn't set-up to do 240 degrees of duration): 8.0mm of lift, 247 degrees duration w/ the entire profile retarded by 7 degrees

Cheers, Trevor*<)

[shotgunslade]

The 247* duration and the 8mm lift were the official specification for the 1993 Nissan 300ZX cam whose profile was used to grind these cams. I understand that there is some confusion with respect to exactly how these numbers were derived, especially with respect to how exactly the start of opening and the end of closing are defined, and whether or not they are comparable to the numbers given for the stock SVX camshaft. My understanding is that 118* lobe centering means that the maximum lift of the camshaft, the center of the camshaft lift profile, occurs 118* ATDC.

[Trevor]

The 247* duration and the 8mm lift were the official specification for the 1993 Nissan 300ZX cam whose profile was used to grind these cams. I understand that there is some confusion with respect to exactly how these numbers were derived, especially with respect to how exactly the start of opening and the end of closing are defined, and whether or not they are comparable to the numbers given for the stock SVX camshaft. My understanding is that 118* lobe centering means that the maximum lift of the camshaft, the center of the camshaft lift profile, occurs 118* ATDC.

Sorry but you are not "understanding". Please read and understand the figures I have posted and apply these. This thread is already confused and further explanation is hardly necessary.

[Trevor]

No flattery required...but thankyou.

I'm unsure whether lift and closing ramp shapes differ...I would suspect not. In fact most cam graphs I've seen show a perfect arc...suggesting that both ramp shapes are identical. I expect it may also be a machining issue.

A relationship does exist with cams and piston position. It is referred to as the lobe centre angle, centre line etc. This is always quoted as a degree of BTDC and ATDC eg 110-115 degrees. For example, for inlet cams, 110 degrees AFTER TDC is the point that the inlet valve is fully open. Adjustment of these centre lines changes things like overlap etc. Longer duration cams usually mean the centre angles are reduced...but then other problems arise, like idle etc.

My reading of the site says that this is usually where the "interference engine" issue arises...but you'll notice that the valve is fully extended when the piston is 110 degrees after TDC...hence it's 2/3 the way down the bore (or 50mm when we are talking about 8-10mm lift ;)).

Where I am curious is that given the exhaust cam drives the inlet cam in a geared arrangement, just how much adjustability do we have to select optimum centre angles assuming a vernier wheel is fitted...I suspect not much. A vernier cam wheel will only allow mutual advancing/retarding with both cams acting as a unit...rather than individual adustments which is optimum. This could be a limiting factor but I suspect if it is, it would only be a minor one.

Thanks, you confirm that my knowledge and assumtions are correct. I had thought that may be some aspects regarding cam grinding may have passed me by, in addition to the 0.05 stuff. I admit to being one old bugger.

The problem with a cam belt breaking is that this could leave a valve stationary at full lift.

A minimum adjustment 7.2 degrees, i.e. one gear tooth, is available, without mods, along the lines that you suggest.

N.B. The interesting point is that, what has been posted indicates that Harvey's specs, on which the reground cams now in use are based, called for the " the entire profile to be retarded by 7*. No evidence has been produced indicating that this was carried out. How were they timed when fitted? This MUST be sorted out.

P.S. What figure do cam grinders use when specifying valve lift? The figure provided for the reground cams is .31055", 7.89mm, if plus 1,27 this could mean 9.16 mm !!??

[oab_au]

Chike PMed me back in July 05, to say he wanted to do some cam upgrades. We talked about what he wanted out of the mods. Basically to run the 1/4 mile in under 15 seconds, with a low final drive ratio auto. I suggested that he go with more lift, and leave the duration the same to preserve as much of the IRIS torque as possible.

We were looking for a profile that gave 240* duration and 8mm lift, by retaining the same base circle diameter, which meant welding the lobe and grinding the new profile.

Chike spent a considerable amount of time and effort checking out the cam grinders that could do the job. Delta was one of the few that would do it, only problem was the closest they had to the desired profile was a KA24DE from a Nissan. This had the lift, but was quoted to have 247* duration (seat to seat). This was going to eat into the IRIS torque below 4000 rpm.

As a compromise to get the cam to deliver the best outcome for running the 1/4, I decided to increase the Maximum valve open, lobe center setting, to 121*ATDC. This would have the effect of moving the torque peak up the rev range, and allowing the inlet opening point, to stay around the same to keep the best of the IRIS torque.

As the Auto with 4.44 gearing would only be operating lower than 4000 rpms on the initial take off, and would spend the rest of the run in the 4000 to 6500 range, I felt that we could get the best, out of the only profile that we had to work with.

This was a one off experiment to see what the results would be. But before we got to try it, Tom whacked a set in his manual gear boxed car, to run the first under 15 sec 1/4. So much for all Chikes work.:rolleyes: Next thing Tom has them recommended for all.

As I pointed out in Danny's thread,
http://www.subaru-svx.net/forum/showpost.php?p=351096&postcount=164
the right set for a auto should stay with the standard duration and lobe center setting, just the 8mm lift. A manual geared car could use a cam with more duration and a lobe setting to suit the rev range that the final drive gearing will allow.

The cams that have been ground to these specifications can have the lobe center moved back to the standard setting by fitting an offset key to the drive gear. The SVX exhaust cam profile would be better for a one for the inlet cam for a standard auto.

Harvey.;)

[Trevor]

Chike PMed me back in July 05, to say he wanted to do some cam upgrades. We talked about what he wanted out of the mods. Basically to run the 1/4 mile in under 15 seconds, with a low final drive ratio auto. I suggested that he go with more lift, and leave the duration the same to preserve as much of the IRIS torque as possible.

We were looking for a profile that gave 240* duration and 8mm lift, by retaining the same base circle diameter, which meant welding the lobe and grinding the new profile.

Chike spent a considerable amount of time and effort checking out the cam grinders that could do the job. Delta was one of the few that would do it, only problem was the closest they had to the desired profile was a KA24DE from a Nissan. This had the lift, but was quoted to have 247* duration (seat to seat). This was going to eat into the IRIS torque below 4000 rpm.

As a compromise to get the cam to deliver the best outcome for running the 1/4, I decided to increase the Maximum valve open, lobe center setting, to 121*ATDC. This would have the effect of moving the torque peak up the rev range, and allowing the inlet opening point, to stay around the same to keep the best of the IRIS torque.

As the Auto with 4.44 gearing would only be operating lower than 4000 rpms on the initial take off, and would spend the rest of the run in the 4000 to 6500 range, I felt that we could get the best, out of the only profile that we had to work with.

This was a one off experiment to see what the results would be. But before we got to try it, Tom whacked a set in his manual gear boxed car, to run the first under 15 sec 1/4. So much for all Chikets work.:rolleyes: Next thing Tom has them recommended for all.

As I pointed out in Danny's thread,
http://www.subaru-svx.net/forum/showpost.php?p=351096&postcount=164
the right set for a auto should stay with the standard duration and lobe center setting, just the 8mm lift. A manual geared car could use a cam with more duration and a lobe setting to suit the rev range that the final drive gearing will allow.

The cams that have been ground to these specifications can have the lobe center moved back to the standard setting by fitting an offset key to the drive gear. The SVX exhaust cam profile would be better for a one for the inlet cam for a standard auto.

Harvey.;)

Harvey,
The above verbose self appraisal when unravelled and abbreviated states --

The duration being considered was 247* seat to seat and the lobe centre was decided as 121* ATDC (Ed. OM is 120*).

(The editors explanation -- Therefore opening would be at 2.5* BTDC (OM 2) and closing at 64.5* ABDC (OM 54) )

Therefore -- the plan was no more than to simply extend the closing of the inlet valve by a minimal 10.5*. Hence Tom's plea for more, which commenced this never ending thread.

Interesting extracts from the above:-

"I decided to increase the Maximum valve open, lobe center setting, to 121*ATDC."

"The cams that have been ground to these specifications can have the lobe center moved back to the standard setting by fitting an offset key to the drive gear."

In point of fact the lobe center has not been shifted. ( OM specs. 120* Grinders, 120.6*, proposal, 121*, i.e. aLL figureS no more than the tolerance of calculations.) The above statements by Harvey provide complete confusion, particularly in respect of what follows.

Harvey your explanation does not tie in with what Tom stated and you have not answered the question I put to you as a means of clarifying the position. I repeat, where does the the stated, "seven degrees retarded" fit in. There are others also confused regarding this issue. Again I repeat :-

Quote 15/05/06 -- "The ideal intake cam specs Harvey recommended for a 4EAT SVX are as follows: 8.0mm of lift, 240 degrees of duration
We settled on the following specs for the weld-n-grind on the intake cams (their machine wasn't set-up to do 240 degrees of duration): 8.0mm of lift, 247 degrees duration w/ the entire profile retarded by 7 degrees

N.B. Were those who have fitted the cams instructed, to retard the cams by one tooth, (i.e. 7.2*), when they were fitted and was this in effect carried out ? :confused: :confused:

[Trevor]

Greetings Matt,

Could you please assist me by answering a question put to Harvey, but passed over :-

What figure do cam grinders use when specifying valve lift? The figure provided for the reground cams is .31055", 7.89mm, if plus 1.27, a figure I think you mentioned, this could mean 9.16 mm !!??

Thanks, Trevor. *<)

[dynomatt]

Trevor, the 0.050" or 1.27mm is used as a repeatable benchmark point in order to measure duration. For this reason, they know, at these small lifts when in fact, the valve is still virtually closed, the duration is able to be the same every time they measure it. Were as advertised duration can vary each time it's tested based on varations within the lash adjusters (by way of example).

The figures of 0.050" bear no relation to the total lift of the cam and should not be considered.

I'd be confident that if the cam grinder figure is quoted as valve lift, then it should be the absolute valve lift.

[Trevor]

Trevor, the 0.050" or 1.27mm is used as a repeatable benchmark point in order to measure duration. For this reason, they know, at these small lifts when in fact, the valve is still virtually closed, the duration is able to be the same every time they measure it. Were as advertised duration can vary each time it's tested based on varations within the lash adjusters (by way of example).

The figures of 0.050" bear no relation to the total lift of the cam and should not be considered.

I'd be confident that if the cam grinder figure is quoted as valve lift, then it should be the absolute valve lift.

Thanks,

I was fully aware as to why the 0.050" factor is used in respect of valve timing but, was concerned that possibly, although unlikely, this could be applied to lift specificatons, in order to maintain a common denominator.

Your advice is much appreciated.

[Trevor]

Harvey,

You continue your habit of not answering questions which may result in your embarrassment. The important issue is that other members are disadvantaged as a result of your impropriety. More important still, is that on this latest occasion, money and considerable time and effort is involved. You are being unfair to those who trusted you. Is it that the issues now being discussed, are beyond you? In any event this would be a poor excuse.

It would appear reasonable to assume that you did in fact intend that the cams should be retarded by one tooth (7.2*) when fitted and your latest statement could be in error. Retarded the figures would be :-

Opening, 9.7* BTDC (OEM 2*). Closing, 55* ABDC (OEM 54).

It may be more than a coincidental that the exhaust figures, which have been discussed as a possible alternative for the the inlet, are :-

Closing 9* ATDCO. Opening 55* BBDC.

If the cams have not in fact been fitted retarded one tooth, it is my contention that this should be tried as a worthwhile experiment.

As I keep pointing out, this is a vital issue for those who, have spent money having cams modified. Did you intend that the cams be fitted one tooth retarded ??? Please answer ----- YES or NO.

[TomsSVX]

I have made my decision a while ago to go ahead and have my next set of cams drawn to the design of the exhaust profile. My only question I have been waiting for to be answered is, what should we do witht he exhaust cams, leave them be for a mild gain or should we be more focused on what we should do with them next. I apologize for my absence but I have merely been listening in and taking notes at this point.

Tom

[Trevor]

I have made my decision a while ago to go ahead and have my next set of cams drawn to the design of the exhaust profile. My only question I have been waiting for to be answered is, what should we do witht he exhaust cams, leave them be for a mild gain or should we be more focused on what we should do with them next. I apologize for my absence but I have merely been listening in and taking notes at this point.

Tom

Tom,

I do not think this will extend the closing duration to what is required to make a worthwhile difference, i.e. raise the power band to the necessary level of RPM, which you will require. You should note that I have been confident enough to publish my suggestions and lay myself open to criticism, which should mean something.

We now await Harvey's answer regarding the suggested 7* delay issue, but in view of history, I am not holding my breath.

P.S. Do you have in mind shifting the exhaust pattern profile forwards by one tooth on the gear, i.e. 7.2* so as to provide 1.8* BTDC, 62.2 ABDC ?

Cheers, Trevor.

[TomsSVX]

I have not thought about adjusting the gears at all. I figured that when I actually do call scott at Delta we can talk about what durations we can use with the new profile. he was easy to work with during the first run so I figured he would be more than willing to help out with a second. With the ability to adjust the lobe centers. there is no need to fiddle with the gears themselves

Tom

[Trevor]

I have not thought about adjusting the gears at all. I figured that when I actually do call scott at Delta we can talk about what durations we can use with the new profile. he was easy to work with during the first run so I figured he would be more than willing to help out with a second. With the ability to adjust the lobe centers. there is no need to fiddle with the gears themselves

Tom

Tom, the lobe centres can not be, to any real extent, be adjusted in relation to the shaft by welding and grinding. You must regard the lobe centres as fixed in relation to the shaft. As a result the minimum practical adjustment available is 7.2* i.e. one gear tooth. The alternative is a stepped key or whatever and things are getting complicated.

[TomsSVX]

Yes, I would say they are getting more complicated because what I thought I knew of our previous cams is now proven incorrect. So all things said at this point you are suggestting using the exhaust cam profile and retarding the exhaist cam 1 tooth(7.2*) in order to raise the powerband? This would be an ideal setup for someone like me who is spiking off the rev limiter with 6 gears

Tom

[Trevor]

Yes, I would say they are getting more complicated because what I thought I knew of our previous cams is now proven incorrect. So all things said at this point you are suggestting using the exhaust cam profile and retarding the exhaist cam 1 tooth(7.2*) in order to raise the powerband? This would be an ideal setup for someone like me who is spiking off the rev limiter with 6 gears

Tom

No Tom I am not suggesting this as the best way to go. It would appear that you have not properly read the thread. I have published what I consider are the most logical inlet figures and you you should refer back for them in this thread and understand the thoughts behind them.

I now add figures which I consider best in respect of the exhaust cams. In all of this I understand that that you will have to compromise by using the nearest profile the cam grinder may have on hand. A few degrees either way should not be of concern, provided that alterations are applied with due consideration.

Exhaust Duration:- 267* or alternatively, 275* i.e. seat to seat.

Opening:- 75* BBDC or alternatively, 80*.

Closing:- 12* BTDC or alternatively, 15*.

You must accept that these figures are based on my estimate of your requirements and you must be the final judge. In this regard I do not regard the second set of figures included, as representing a wild cam grind. You have tried the very coservative approach and have made it clear that you wish to be a little more adventurous.

The induction control system should remain effective further up the rev range. However I would firmly suggest that a switch be placed in the induction control valve circuit, so that runs can be timed with the valve constantly open, as a simple worthwhile experiment.

FIxed short inlet tracts are after all in line with sporting requirements and the original system is fitted mainly for the benefit of the commuter driver. This is not rocket science and the principals will be well known to all and I hope our lecturer does not jump in and tell us all how to suck eggs! The flat more even power curve may pay dividends, even though on paper there is shown to be a small loss on the way up. I would accept repetitive runs at the strip, as being more reliable than dyno testing and a lot more fun and cost effective! Have some on me. :D

***** P.S. Tom you have said :- "Yes, I would say they are getting more complicated because what I thought I knew of our previous cams is now proven incorrect."

A problem remains in that we do not in fact know exactly what is incorrect. Harvey has selfishly not answered a simple yes or no, to my continuing question in this regard. Meantime we all remain in the dark. However I do agree that the specified duration, whichever way arranged, had little chance of providing any real kick in the butt.

[oab_au]

I have made my decision a while ago to go ahead and have my next set of cams drawn to the design of the exhaust profile. My only question I have been waiting for to be answered is, what should we do witht he exhaust cams, leave them be for a mild gain or should we be more focused on what we should do with them next. I apologize for my absence but I have merely been listening in and taking notes at this point.

Tom

Tom you would be wasting your time using that cam in your 6 speed car. You really need to be looking around the Stage 2 that I suggested. Around 15 to 20* extra duration and more lift.

These cams that Mychailo found look the goods.
http://www.subaru-svx.net/forum/showpost.php?p=372032&postcount=5
8.75 mm lift on each, and around 200* duration. These are very close to the set that my Son used in his 3 Lt Datsun. Running these cams, with a 119* inlet LC, 114* exhaust LC, on a model, gave these figures.

RPM 3000 4000 5000 6000 7000
Kw 73 129 182 203 204
Nm 232 309 348 324 279

These would suit the 6 speed gear box that you have, and produce the level of performance you are looking for.

Harvey.;)

[dynomatt]

Second the comment that the exhaust profile isn't going to get you where you want to be.

Advertised of about 250 degrees would be nice which probably equates to close to 210-220 ish at 0.050".

Can the stock EFI system deal with that?

Matt

[TomsSVX]

the stock air metering system cannot but the fuel system can. By using my Stage2v5 ECUtune I can now reach appropriate power levels without losing my ability to accurately monitor airflow and temp.

Harvey, no offense but I would like to ask the others in this thread if these figures seem correct. I would also like the question the possibility of valve float at 8.75mm of lift with more duration. Don't forget it will be spinning at or around 7krpms

Tom

[dynomatt]

Valve float is very unlikely. Remember, that's traditionally been the domain of large single valves, rather than a multi-valve arrangement.

I don't subscribe to Harvey's 8.75mm of lift theory but then he hasn't replied to me why that is. I'm looking for a much more aggressive profile and will be aiming for about 10mm with probably about 270-280 advertised duration.

[TomsSVX]

From what I understand Subaru is well know for keeping their valve tensions low. I also believe we get coilbind at 9.5mm of lift:confused: I am looking for something to give me significant gains but still allow the car to be streetable. I am also not sure that higher lift will give us a better gain as you are implying:confused:

Tom

[dynomatt]

According to others, coil bind is correct at that lift. I'm proposing new springs.

Mine is not going to be streetable...in fact, quite the opposite.

From my perspective, you (and me when I get my car) will be going to lengths nobody else has gone to...does that mean we will have problems, absolutely...does that mean that anybody else knows what will happen, absolutely not.

I think you've reached the point where you're starting to get too much information. It's now up to you to make a decision and go with it.

You can be conservative with cam choice and not suffer...if you go too wild, you will suffer.

I think the 10mm is reasonable. I base this on my prior knowledge about the point where you get maximum flow, and also on the work done by VTSuby who claims max flow is at about 10.something mm lift.

Flow = HP, but it's up to the package of EVERYTHING to realise that. Just changing the cams to the spec that gets you the most flow, will not realise the gain. It will come with ECU changes, compression, headers, intake changes etc. Then, and only then, will max power be achieved.

You' re after a streetable package. What one person defines as streetable is very different to anothers. Will your proposed cam be streetable absolutely. Will mine...they might be (by streetable I mean that mine would only make power from 5000rpm up!!).

At the end of the day, you're on the edge...make an educated decision, and live with the consequences.

Either way, I firmly believe there is more to be gained, and you sound like you're in the best position to test that.

As I've said before, I'd be interested to find more about the WRX that had a claimed 212hp ATW. Lots of factors can affect that outcome, but frankly I think it's worth exploring, because what it says to me is that with just a simple change to an aftermarket programmable ECU, 20-40hp can be found. That's cheaper than cams.

Matt

[TomsSVX]

Thanks for your help guys, I am now on the fence about a lot of things I will see how it goes in the next couple weeks

Tom

[Trevor]

Interesting that none have the balls to back their hot air with exact figures. Not even within + or - 7.2*. :(

[dynomatt]

Trevor,

You'd be aware that I don't own one of these yet. You'd be also aware that I have some knowledge, and am not just another punter.

I'm prepared to stake my claim on the combination of my knowledge (gained from past experience) and the commitment to try it out once I get a car.

Until then, I agree, it's potentially hot air but it's certainly more educated than some.

Matt

[oab_au]

Valve float is very unlikely. Remember, that's traditionally been the domain of large single valves, rather than a multi-valve arrangement.

I don't subscribe to Harvey's 8.75mm of lift theory but then he hasn't replied to me why that is. I'm looking for a much more aggressive profile and will be aiming for about 10mm with probably about 270-280 advertised duration.

Sorry Matt if I missed the question.:(
If you want to give me the Lobe center settings that you would like the 10mm lift, 275* cams run at, I'll give you an idea what the results would be.

Harvey.;)

[Trevor]

Trevor,

You'd be aware that I don't own one of these yet. You'd be also aware that I have some knowledge, and am not just another punter.

I'm prepared to stake my claim on the combination of my knowledge (gained from past experience) and the commitment to try it out once I get a car.

Until then, I agree, it's potentially hot air but it's certainly more educated than some.

Matt

I agree Matt and I hope I may have provoked you towards submitting figures which have been applied to the rally cars you mention as having workrd on.

The debate had the potential to contain real content, but this has sadly been missing. There will surely be many interested in this subject provided facts are included. To date there has been little submitted in the way of honest fact.

[Trevor]

Sorry Matt if I missed the question.:(
If you want to give me the Lobe center settings that you would like the 10mm lift, 275* cams run at, I'll give you an idea what the results would be.

Harvey.;)

Presuming that the question relates to the subject of this thread, I will state that a lift of 10mm i.e. an increase of 42% is not feasible on several grounds. An exact assessment of all the results i.e. exactly that which will occur in all respects, will be awaited with interest.

Harvey, we are still awaiting adivice on the lobe centre settings intended in respect of the modified cams specified by you, but paid for by others. This has become THE question.

[dynomatt]

Harvey are you using Engine Analyser Pro? If so, I'd be keen to get some of the engine detail that I'm missing from so that I can play too.

Lobe centres for this motor would probably be about 105-110 degrees.

Trevor...I'd like more info to backup why the 10mm lift I'm proposing "is not feasible on several grounds". I'm proposing 10mm as a good start given the valve sizes, and am well aware that the valve springs are a problem. I'm proposing a change to them and also may need to grind down the bucket retainers to clear the cam. But otherwise, I'm not sure why it's a problem?

I'm exploring whether I can get the compression ratio to about 12:1 too as I think that's where I want to aim for rally use.

Matt

[oab_au]

Harvey are you using Engine Analyser Pro? If so, I'd be keen to get some of the engine detail that I'm missing from so that I can play too.

Lobe centres for this motor would probably be about 105-110 degrees.

Trevor...I'd like more info to backup why the 10mm lift I'm proposing "is not feasible on several grounds". I'm proposing 10mm as a good start given the valve sizes, and am well aware that the valve springs are a problem. I'm proposing a change to them and also may need to grind down the bucket retainers to clear the cam. But otherwise, I'm not sure why it's a problem?

I'm exploring whether I can get the compression ratio to about 12:1 too as I think that's where I want to aim for rally use.

Matt

I use a licenced one from Lotus Engineering. If you PM me with what you need, I'll give it to you.

Harvey.;)

[Trevor]

Harvey are you using Engine Analyser Pro? If so, I'd be keen to get some of the engine detail that I'm missing from so that I can play too.

Lobe centres for this motor would probably be about 105-110 degrees.

Trevor...I'd like more info to backup why the 10mm lift I'm proposing "is not feasible on several grounds". I'm proposing 10mm as a good start given the valve sizes, and am well aware that the valve springs are a problem. I'm proposing a change to them and also may need to grind down the bucket retainers to clear the cam. But otherwise, I'm not sure why it's a problem?

I'm exploring whether I can get the compression ratio to about 12:1 too as I think that's where I want to aim for rally use.

Matt

Hi Matt,

You have in fact detailed some of the problems you must overcome. I do not believe the modifications are feasible. I welcome you to prove me wrong and in fact would applaud you if you can do so. Sincerely I wish you the very best in your endeavor and hope you are successful.

Cheers, Trevor.

[TomsSVX]

Well, looks like you will need another test dummy. looks like the silver popped a HG recently and I am going to do it right with a different kind of build. Anyone who knows why I would want to raise lift to 8mm and reduce overlap will know what I want to do. Anyway thank you all for your input and advice, I am sure some more modders in the future will find this info very usefull.

Tom

[Trevor]

Well, looks like you will need another test dummy. looks like the silver popped a HG recently and I am going to do it right with a different kind of build. Anyone who knows why I would want to raise lift to 8mm and reduce overlap will know what I want to do. Anyway thank you all for your input and advice, I am sure some more modders in the future will find this info very usefull.

Tom

I guess you not mean, "to raise lift to 8mm and INCREASE overlap".

I understand there are others who have the same cam grind as you used and therefore may be seriously affected, as Harvey's intended position for the lobe centers has never been confirmed. Furthermore without this information, it is imposslble to establish any conclusions as a result of the work you have done, which as you say, could assist others in the furure and this is a shame.

Do you have any information in this regard, as nothing appears to be forthcomig from Harvey? In particular were your cams set as per OEM timing marks, or offset one gear tooth and if so in which direction?

[NeedForSpeed]

I'm guessing he meant what he said, decrease overlap. Tom has a couple turbos looking for some air to move.

I guess you not mean, "to raise lift to 8mm and INCREASE overlap".

I understand there are others who have the same cam grind as you used and therefore may be seriously affected, as Harvey's intended position for the lobe centers has never been confirmed. Furthermore without this information, it is imposslble to establish any conclusions as a result of the work you have done, which as you say, could assist others in the furure and this is a shame.

Do you have any information in this regard, as nothing appears to be forthcomig from Harvey? In particular were your cams set as per OEM timing marks, or offset one gear tooth and if so in which direction?

[svxsubaru1]

Tom you would be wasting your time using that cam in your 6 speed car. You really need to be looking around the Stage 2 that I suggested. Around 15 to 20* extra duration and more lift.

These cams that Mychailo found look the goods.
http://www.subaru-svx.net/forum/showpost.php?p=372032&postcount=5
8.75 mm lift on each, and around 200* duration. These are very close to the set that my Son used in his 3 Lt Datsun. Running these cams, with a 119* inlet LC, 114* exhaust LC, on a model, gave these figures.

RPM 3000 4000 5000 6000 7000
Kw 73 129 182 203 204
Nm 232 309 348 324 279

These would suit the 6 speed gear box that you have, and produce the level of performance you are looking for.

Harvey.;)


Sorry for coming in late, but has any one tried using this cam on there SVX yet? Ive been acking for some more power up top and will staring having some some funds to get stuff done, and it seems like some cams a ecutune stage 2 would help alot. Has that much lift been used succsefully with the stock SVX vavle springs? Or do you think it would work? Would it still pass emmisions?

[oab_au]

Sorry for coming in late, but has any one tried using this cam on there SVX yet? Ive been acking for some more power up top and will staring having some some funds to get stuff done, and it seems like some cams a ecutune stage 2 would help alot. Has that much lift been used succsefully with the stock SVX vavle springs? Or do you think it would work? Would it still pass emmisions?

Haven't been used on a SVX, that I know of. Used the same in a Datsun with a RB30 block with a RG25 head on it. This is the G-Tec scan of the old 240*,7.8mm lift, and the new 257* 8.75mm lift cams.
http://www.subaru-svx.net/photos/files/oab_au/36322.jpg
You can compair the differences that the increase in lift and duration gave, in this case. The engines are very close in specs. though the out put figures that I posted for the EG33 would be the likely results.

From what we know now 9mm is possible, so the lift will be ok. Depending what rpms you go to, stronger springs would help. Emissions should not be affected.

Harvey.;)

[Trevor]

Harvey,

Copied below is the collected figures/information, associated with the above extensive, impressive but disorganized post.

"8.75 mm lift on each, and around 200* duration. These are very close to the set that my Son used in his 3 Lt Datsun. Running these cams, with a 119* inlet LC, 114* exhaust LC, on a model, gave these figures."

RPM 3000 4000 5000 6000 7000
Kw 73 129 182 203 204
Nm 232 309 348 324 279

(Edit. N.B. 119* LC = 238* duration, 114* LC = 228* duration? Are these figures @ 0.050" ?)

These cams that Mychailo found look the goods
"S14 KA24DE motor (late model 240SX)
intake profile: 0.350" lift, 206 deg @ 0.050" (a bit too much duration)
exhaust profile: 0.350" lift, 200 deg @ 0.050" (almost too much duration, but probably ok)."

(Edit. The LC is not specified. "Too much duration"?? Not so eh Mychaillo!!)

"Haven't been used on a SVX, that I know of. Used the same (Edit. Presume same lift?) in a Datsun with a RB30 block with a RG25 head on it. This is the G-Tec scan of the old 240*,7.8mm lift, and the new 257* 8.75mm lift cams."

(Edit. Are these figures @ 0.050" ? The LC is not specified.)

We are advised that the information relates to a "Datsun with a RB30 block with a RG25 head on it". Specifications would be very helpful, as we are not Datsun enthusiasts. Given that one sees them as relevant.

The information one can glean, is that there was a meagre improvement registered, amounting to 8% in H.P. and 4% in torque (Torque at increased RPM). Power fell off badly at 5,650 RPM. In my book not worthy of the effort. Those involved here will be looking for much more and certainly power from 6.000 RPM on through 7,000 RPM.

The one specific which can be gained from the post, is that you place a great deal of emphasis on valve lift. You state, " From what we know now 9mm is possible, so the lift will be ok." I state that attempting an increase of 29% above the original specifications would foolhardy, all positive/negative factors taken to account. Eight m.m. is a reasonable figure, i.e. 14%. What is ultimately possible is not necessarily desirable or effective.

Advice as to your reasoning that 9 m.m. is OK, Most of all, supporting figures covering the actual gain in increased port area relative to time, that would be achieved, will I hope be provided. These figures will impress much more than irrelevant charts.

Cheers, Trevor *<)

[oab_au]

Moving the Lobe Center.

The Lobe Center (LC) or the Maximum Open Position (MOP) is the crankshaft position
in degrees, when the valve is fully open. As the valve is only fully open for a short time,
we need to arrange things, to allow the maximum amount of air to enter the cylinder. This
will only happen, if the inlet valve is fully open, when the air is flowing at its maximum
speed.

The air speed is caused by the piston speed, which reaches its maximum speed at about
84* After Top Dead Center. So if the piston moves slowly the air will follow it at the
same speed. As the piston speed increases to about 3000 rpm, the air which has to flow
through the inlet passages, tends to lag behind the piston, so that the maximum air speed
is occurring later in the cycle. Instead of it being at 84* ATDC it is occurring at about
100* ATDC.

If we want to build an engine that will have maximum torque at 5000 rpm, we need to set
the cam up so that the maximum air speed and the MOP coincide at the same time. In our
SVX .engine this is around the maximum torque peak of 4800 rpm. The air will reach its
maximum at about 114* ATDC, so we time the cam so that it is fully open at 114*
ATDC. If we want to move the torque peak further up the rpm range, we need to retard
the cam position, to have the MOP latter in the cycle, to where the maximum air speed is.

We can also use this feature to adjust the torque peak to a slightly different position, as I
did with the cam that Chike had made. As this was for the drags, I decided to retard the
cam to 121*ATDC, to stretch the torque further up the rev range, so that the torque held
up for longer up the range, and the high rev end was enhanced.

Going back to the scans of the cam used in the Datsun, we have this one where the Lobe
center is around 100*ATDC. the thing to note is the dotted curve that is the torque curve
peaks about 4500 rpm then drops off.

http://www.subaru-svx.net/photos/files/oab_au/36354.JPG

This next one shows the same cam retarded to 120* ATDC, you can see the way the
torque curve still peaks at around 4500 rpm, but instead of dropping off, it continues to
hold good torque to around 5600 rpm.

http://www.subaru-svx.net/photos/files/oab_au/36355.JPG

We do pay a penalty by a lower peak torque, but
the wider spread of torque offsets the loss, while increasing the HP, for the conditions that the quarter mile
demands.

Harvey.

[shotgunslade]

Harvey:

Thanks for this informative post. I now understand why the recommendation for the '93 Nissan 300zx camshaft for SVX's running a 3.9 final ratio 5MT was 118 ATDC. If that spec was given to the cam grinder, I suppose he would adjust the rotational location of the cam in the grinding apparatus, keyed to the indicator on the camshaft drive gear, so that, when properly installed, on the right sprockets, the camshaft would be a maximum lift at 118 ATDC. So the variables are, did the camshaft grinder grind it to specifications, and was it installed on the right gear tooth location?

Dan

[oab_au]

Harvey:

Thanks for this informative post. I now understand why the recommendation for the '93 Nissan 300zx camshaft for SVX's running a 3.9 final ratio 5MT was 118 ATDC. If that spec was given to the cam grinder, I suppose he would adjust the rotational location of the cam in the grinding apparatus, keyed to the indicator on the camshaft drive gear, so that, when properly installed, on the right sprockets, the camshaft would be a maximum lift at 118 ATDC. So the variables are, did the camshaft grinder grind it to specifications, and was it installed on the right gear tooth location?

Dan

Thanks Dan, as far as I know the profile was the KA24DE engine from the 240SX? the actual retard was 121* ATDC, and yes the retard was ground into the cam lobe, so that you only had to install it, without having to change anything. I don't doubt that Delta did the grind right, but it has not been checked by anyone.

How would you describe the effects of the cam change, compared to the original. Chike, Tom and Myxalplyx might like to give there impressions also,as to how it worked out in practice.

Harvey.;)

[shotgunslade]

It is really hard to say, because so many other things were changed at the same time, 5MT, and adjustable fpr being two of them. I am very pleased with the acceleration of the car. I have a GTech run that young Tom did before the mods, but I haven't yet had an opportunity to get a post mod run. I'm going for a track day (road track, not drag strip) this weekend. maybe I'll try to get a GTech run while I'm there.

[oab_au]

It is really hard to say, because so many other things were changed at the same time, 5MT, and adjustable fpr being two of them. I am very pleased with the acceleration of the car. I have a GTech run that young Tom did before the mods, but I haven't yet had an opportunity to get a post mod run. I'm going for a track day (road track, not drag strip) this weekend. maybe I'll try to get a GTech run while I'm there.

Yes I can understand, with the other changes too. It will be interesting to see how the torque curve suits the 6 speed on a circuit. I would guess that it will cover the rev range that you would use, to make it very forgiving. You know " wrong gear, wrong speed, wrong line" the torque covers it.:D

Like to know what rev range you used, like 4 to 6.5, 5 up?, what was your main rpm centred on.? I would like to do this next set of cams to suit the 6 speed, operating in the 5 to 7.5 range.

All the best next week end.
Harvey.;)

[shotgunslade]

Harvey:

I have the 2004 WRX 5 speed. Here is a table of the gears, rpms, and theoretical speed in mph:

Final Drive Ratio--3.9---------------------Wheel Diameter--24.72

Gear---Ratio----2000----3000----4000----5000----6000----7000
1------3.454-----11-------16------22------27-------33------38
2------1.947-----19-------29------39------48-------58------68
3------1.366-----28-------41------55------69-------83------97
4------0.972-----39-------58------78------97------116-----136
5------0.738-----51-------77-----102-----128------153-----179

The engine really comes on strong at 3500-4000 rpm and really digs in until at least 6500. It likes to rev. Can't really say if it is worthwhile to take it up to the 7200 red-line, especially since I'm not drag racing. Mostly I find myself in 3rd and 4th. It takes a pretty tight hair-pin to put me down into 2nd. I haven't yet found a long enough straight to get into 5th.

[oab_au]

Harvey:

I have the 2004 WRX 5 speed. Here is a table of the gears, rpms, and theoretical speed in mph:

Final Drive Ratio--3.9---------------------Wheel Diameter--24.72

Gear---Ratio----2000----3000----4000----5000----6000----7000
1------3.454-----11-------16------22------27-------33------38
2------1.947-----19-------29------39------48-------58------68
3------1.366-----28-------41------55------69-------83------97
4------0.972-----39-------58------78------97------116-----136
5------0.738-----51-------77-----102-----128------153-----179

The engine really comes on strong at 3500-4000 rpm and really digs in until at least 6500. It likes to rev. Can't really say if it is worthwhile to take it up to the 7200 red-line, especially since I'm not drag racing. Mostly I find myself in 3rd and 4th. It takes a pretty tight hair-pin to put me down into 2nd. I haven't yet found a long enough straight to get into 5th.

Using your info into the gear calculator here:

http://www.geocities.com/z_design_studio/transmission.html

Shows that you will do most of the work, between 4500 and 6500. the only difference will be 1st to 2nd, 6500 in 1st will drop to 3500 in 2nd. So it may be worth going a bit higher in 1st to keep it up the rev range in 2nd.

Looks good.:)

Harvey.;)

[cdigerlando]

I will be looking at doing cams for my engine rebuild and was wondering if there are any suggestions for modifications with a boosted engine (15-20 psi) running 8.5:1 compression. Great thread by the way.

Thanks

Chuck D.

[Trevor]

I will be looking at doing cams for my engine rebuild and was wondering if there are any suggestions for modifications with a boosted engine (15-20 psi) running 8.5:1 compression. Great thread by the way.

Thanks

Chuck D.

You are in a completely different ball park and could be looking at reducing overlap, rather than increasing it. When there is positive pressure and the inlet is open with the exhaust, the inlet charge can become exhausted as it were. Time is the essence. This is not hard to fathom and consider within the equation.

The advantages to be gained by modifications to cam timing are much less than applicable to a normally aspirated engine. This applies particularly in regard to lift, which increases mechanical loadings and you must consider, as you probably will be looking towards increased RPM. (These comments also apply to possible contrary loss factors as a result of supercharging.) In point of fact, forced induction is a means of overcoming all limitations involved in cylinder filling, which therefore become less of an overall factor.

You will see from the thread that no absolutes are involved and you must research and come to your own conclusions. Taking into account cost, work and the need for proper evaluation which really requiring an engine dyno and professional equipment, I would recommend sticking with the OEM cams. Most certainly leave cams at the end of any development list.

Whatever you do, make each mod a separate event, to be tested as such. Otherwise gains in one area can mask losses in another. In too many cases errors are concealed as a result of impatience in this respect.

There will be others that will advise otherwise. Take it or leave it, no problem this end. :)

[cdigerlando]

You are in a completely different ball park and could be looking at reducing overlap, rather than increasing it. When there is positive pressure and the inlet is open with the exhaust, the inlet charge can become exhausted as it were. Time is the essence. This is not hard to fathom and consider within the equation.

The advantages to be gained by modifications to cam timing are much less than applicable to a normally aspirated engine. This applies particularly in regard to lift, which increases mechanical loadings and you must consider, as you probably will be looking towards increased RPM. (These comments also apply to possible contrary loss factors as a result of supercharging.) In point of fact, forced induction is a means of overcoming all limitations involved in cylinder filling, which therefore become less of an overall factor.

You will see from the thread that no absolutes are involved and you must research and come to your own conclusions. Taking into account cost, work and the need for proper evaluation which really requiring an engine dyno and professional equipment, I would recommend sticking with the OEM cams. Most certainly leave cams at the end of any development list.

Whatever you do, make each mod a separate event, to be tested as such. Otherwise gains in one area can mask losses in another. In too many cases errors are concealed as a result of impatience in this respect.

There will be others that will advise otherwise. Take it or leave it, no problem this end. :)


Thanks for the good advice. Efficiency probably is going to be more turbo/supercharger dependant than cam dependent. I was thinking that reduced overlap might help with tuning the turbo, and a slight increased lift as Tom used would help reduce backpressure and heat on the turbo compressor. I like your advice of one thing at a time. Right now I'm thinking about keeping the stock pistons and shaving a bit off them to reduce compression. It all depends on costs.

Thanks

Chuck D.

[Trevor]

Thanks for the good advice. Efficiency probably is going to be more turbo/supercharger dependant than cam dependent. I was thinking that reduced overlap might help with tuning the turbo, and a slight increased lift as Tom used would help reduce backpressure and heat on the turbo compressor. I like your advice of one thing at a time. Right now I'm thinking about keeping the stock pistons and shaving a bit off them to reduce compression. It all depends on costs.

Thanks

Chuck D.

Overlap is the ingrediant to consider within the present topic which can induce increased heat, due to the exhaust valves opening early. Lift as such is not to any extent involved.

When considering increased lift you should take into account the time element involved in any gain in an increased flow path, as this is available for only a short span within the induction cycle. This factor makes perceived gains suspect. Increasing lift also has historical atributes no longer in vogue. Your application i.e. forced induction, negates any possible gain towards zero.

[cdigerlando]

Overlap is the ingrediant to consider within the present topic which can induce increased heat, due to the exhaust valves opening early. Lift as such is not to any extent involved.

When considering increased lift you should take into account the time element involved in any gain in an increased flow path, as this is available for only a short span within the induction cycle. This factor makes perceived gains suspect. Increasing lift also has historical atributes no longer in vogue. Your application i.e. forced induction, negates any possible gain towards zero.

Would you recommend dropping the overlap? If so, by how much would you estimate? I know that boost applications for SVXs run into heat problems. Perhaps this is the reason. I'm not sure what Cobb runs with his grinds. Perhaps that would be a good place to check.

[Trevor]

As I have pointed out this a matter of conjecture. What I would be doing is collecting valve timing data on as many engines as possible, which have been produced in normally aspirated as well as with a turbo. By making comparisons you will be able to assimilate a useful indicator from which to make your own conclusions, cost being an important factor. You are the only one who can define your exact requirements. All in all, this is part and parcel of the fun/game. :)

[oab_au]

Gid'ay Chuck, the combination of a turbo and auto trans, sets the options for any engine work. The main objective is to retain as much of the Inertia inlet systems low speed torque as possible. The turbo won't do a lot till around 3000 rpm, so the inertia torque is needed to fill the low speed end.

With this in mind, I would only fit inlet cams ground on the 8mm lift/244* exhaust profile. The extra lift won't affect the low end, but will benefit the mid/top end, where the breathing tapers off.

The compression ratio that you can run depends on at what rpm you have the boost and how much. An engine can take more boost at higher rpms that at lower rpms. A supercharged engine will have more difficultly running a high ratio, as it has a high boost at low engine rpms, a recipe for detonation. The turbo doesn't have boost at low rpms so the ratio can be higher, than the Supercharged engine. I would just try the engine with the 10:1 ratio, see how it handles the boost, and make future decisions then.

As I have said before, its the up pipe that you have to change, to prevent the exhaust interference that you have been having. The two header pipes must be separated up to the turbo inlet. When you were running it back in 2000? it was ok till the boost and rpms came up. The exhaust pressure from the interference backed up, to push the exhaust gas back into the inlet manifold to spike the pressure up and the engine fouled.

I think if you fix the up pipes, you should be able to keep adding boost as you go, till you meet the limit of the ratio. When you get all the bits sorted, then look at building an engine to suit.:)

Harvey.;)

[Trevor]

In complying with the original subject i.e. cams. ---

A turbo in the exhaust tract will upset the normal inertia inlet system. The exhaust cam profile was originally my suggestion within this thread, but not in this context where it would provide limited if any advantage. The possible advantage of increased valve lift in respect of breathing is marginal and has real disadvantages as I have pointed out. Figures are required to show otherwise.

Weigh up all the issues, pros and cons, cost, work, time available and viability. I say stick with the OEM cams, but as I have stated earlier it is you who must decide and this is part of the fun involved. :)

Go to it, Trevor *<)

[oab_au]

In complying with the original subject i.e. cams. ---

A turbo in the exhaust tract will upset the normal inertia inlet system. The exhaust cam profile was originally my suggestion within this thread, but not in this context where it would provide limited if any advantage. The possible advantage of increased valve lift in respect of breathing is marginal and has real disadvantages as I have pointed out. Figures are required to show otherwise.

Trevor *<)

I think you will find that Tom was the first to suggest using the exhaust profile for the inlet, in another thread. At the time I agreed, as the faster opening would assist the sonic wave.

"A turbo in the exhaust tract will upset the normal inertia inlet system"??????
On what, is this statement based on.?

Harvey.;)

Harvey.;)

[dynomatt]

I speak from experience...overlap and ergo, duration, are the killer of turbo power (or any positive pressure system).

Any overlap allows the boost to blow out the exhaust valve and renders it useless.

A study of OEM cam profiles for turbocharged or supercharged cars will discover this.

Duration is inexorably linked to overlap, but overlap is the killer.

M

[Trevor]

I speak from experience...overlap and ergo, duration, are the killer of turbo power (or any positive pressure system).

Any overlap allows the boost to blow out the exhaust valve and renders it useless.

A study of OEM cam profiles for turbocharged or supercharged cars will discover this.

Duration is inexorably linked to overlap, but overlap is the killer.

M

You are spot on and the previous experts suggestion of using the exhaust cam profile is way out of line. In support of your advice, I repeat my comments from shortly earlier in this thread.

"Overlap is the ingredient to consider within the present topic which can induce increased heat, due to the exhaust valves opening early. Lift as such is not to any extent involved."

"You are in a completely different ball park and could be looking at reducing overlap, rather than increasing it. When there is positive pressure and the inlet is open with the exhaust, the inlet charge can become exhausted as it were. Time is the essence. This is not hard to fathom and consider within the equation."

What else is there for us to say in order to convince ? :confused: ;)

[Trevor]

I think you will find that Tom was the first to suggest using the exhaust profile for the inlet, in another thread. At the time I agreed, as the faster opening would assist the sonic wave.

"A turbo in the exhaust tract will upset the normal inertia inlet system"??????
On what, is this statement based on.?

Harvey.;)

Harvey.;)

1. You think wrong. I well remember, as it was my thoughts concernig old Rileys that brought this prospect to mind and caused me to put it forward.

2. Constriction.

[oab_au]

1. You think wrong. I well remember, as it was my thoughts concernig old Rileys that brought this prospect to mind and caused me to put it forward.

2. Constriction.

No I am right, as usually, check here::)
http://www.subaru-svx.net/forum/showpost.php?p=364522&postcount=131

2. Constriction, ??????????Is that suppose to explain this statement of yours this?:D

"A turbo in the exhaust tract will upset the normal inertia inlet system" ?????? :D

It needs a bit more than that.

Harvey.;)

[oab_au]

I speak from experience...overlap and ergo, duration, are the killer of turbo power (or any positive pressure system).

Any overlap allows the boost to blow out the exhaust valve and renders it useless.

A study of OEM cam profiles for turbocharged or supercharged cars will discover this.

Duration is inexorably linked to overlap, but overlap is the killer.

M

I wouldn't call 11* Overlap.:) 60* to 100* is overlap.:p You must remember that the 11* is 'off the seat timing' in the 11* that the exhaust is closing and the inlet is opening, the valves are so close to the seats, that the amount of loss is very small, but it has the advantage of cooling the exhaust valve and blowing the chamber clear.

As I said above, the engine modifications must suit the gear box, final drive ratio, and the use that the car will have. You won't achieve a usable package by destroying the low rpm torque, when the cars gearing has it doing most of its running in the 1500/2500 rev range.

If the car has a 6 speed and a low final drive ratio, then the loss of the low rpm torque can be accounted for, by using the gears to keep the rpms up in the range, that the boost is present.

Any alteration in the duration or lobe center will degrade the low rpm torque. Using the exhaust cam as the inlet, will not affect the functioning of the IRIS, so the low rpm torque will still be there. The increase in the lift, will just extend the high rpm torque, further up the rev range.

This is only for this installation of Chucks, other setups like NA, supercharging, or gear boxes, will use a combination to suit that particular use.

Harvey.;)

[shotgunslade]

This was the analysis of the camshafts posted by Bill (SVXRide) a few pages ago.

http://www.subaru-svx.net/photos/files/SVXRide/35887.jpg

According to Chike"s original post:
The stock specs are as follows:

Intake Cams: 7.0mm lift, 236 degrees duration
Exhaust Cams: 8.0mm lift, 244 degrees duration



First of all, the lift (.27933) quoted on the Cam Doctor's first exhaust camsahft seems inconsistent with a 1mm increase in lift over the intake lift, in fact it is a smidge lower.

The second interesting statistic here is the "Lobe Area" given in IN*DEG. I would have to guess that is the integral of of the cam lift curve in polar coordinates. In effect, it is the summation of the area of camshaft lift over time (as measured by crankshaft rotation), and thus has a linear equivalancy to the total valve opening over time (area of opening multiplied by degrees of crankshaft rotation).. If this is a true representation of the stock intake cam and the performance intake cam, then the performance camshaft has a little more than 15% increase in total opening area over time. Given that the lift is only 11% more, and the duration is only 3.1% more, it would seem that the performance cam is either spending a slightly disproportionate amount of time fully open, or is opening on a slightly steeper ramp than the stock camshaft. Any comments?

Still don't understand the discrepancy with the quoted stock exhaust camshaft specs.

[cdigerlando]

Harvey:

You seem to have the impression that the turbo exhaust is interfering. I'm not going to say that you are wrong, as I have not resolved the issue that I think is the real problem ............detonation. At the higher RPM ranges I basically felt a drop in timing. I have felt this before in my WRX (not often). I'm pretty sure that the detonation sensors signaled the ECU to retard timing. Fuel consumption is also much higher at higher RPMs. I did not have an AFR reading, but I would be willing to bet that I was running lean, as I did not have bigger fuel injectors. I'm going to work out a number of issues first before I go repiping the uppipe. That would be a last resort, as it would be difficult to plumb into the already crowded system. I would like to also point out that the pipes both point up and combine to a larger uppipe. Not an unusual design for a subaru upipe. In fact I have heard from race shops that the upipe design is of little consequence, as long as it is free of restriction and gets to the turbo as quickly as possible. I'm not saying that they are right and you are wrong, this is what I have heard. At any rate I think it is a secondary issue at this point.

As far as running 10:1 compression, only if I didn't already have to take the engine apart. Many folks are looking to go to 9.5:1. I totally disagree with that, considering the investment in aftermarket pistons and labor to install. Only the 911 turbo designed 9.4:1, and they recently changed back to 9:1. My wife is driving an FXT with 8.4:1 compression. There is no turbo lag. My WRX is running about 8:1. It is very laggy. I will go no higher than 8.5:1. Anything else would be a waste of time in my opinion. Besides there are enough people doing FI that will try these options. I have made my decision, and I will not go any higher.

As for heat problems at high RPMs caused by improper overlap, I think we may be on to something. I have heard that there are problems at extremely high engine output (mid 450 HP) causing cylinder heat problems. Rebello claimed to have resolved this issue. No amount of oil squirting helped resolve it, and they were reluctant to tell me how they did it (job security?)

I don't mean to be abrasive. I appreciate everyone's advice, even if I don't agree. There may be a time when I will have to eat crow and repipe the turbo, but for now I need to work on the bottom and top end of the engine, while I have it apart. I'm really looking to get someone to do the work for me. Rebello sounds really busy, and I'm not sure the guy who originally built these engines even works there anymore. I'm also considering Cobb. We shall see.

Cobb has a number of turbo camshaft grinds that have been tested tuned and dynoed. They also know how to close the deck on a block and have experience installing stronger aftermarket bearings. I may go with them. If I go with anyone, I'm also going to want them to break the motor in and bench tune it. I'm probably also going to need to rob a bank. :(

[Trevor]

No I am right, as usually, check here::)
http://www.subaru-svx.net/forum/showpost.php?p=364522&postcount=131

2. Constriction, ??????????Is that suppose to explain this statement of yours this?:D

"A turbo in the exhaust tract will upset the normal inertia inlet system" ?????? :D

It needs a bit more than that.

Harvey.;)

You appear to be able to understand what the word means. :p You seem to now be stating that the exhaust system has no effect on aspiration and or possibly that a turbo is perpetually powered. :D I leave you with the opportunity to self gratify with another lecture.

[Trevor]

This was the analysis of the camshafts posted by Bill (SVXRide) a few pages ago.

http://www.subaru-svx.net/photos/files/SVXRide/35887.jpg

According to Chike"s original post:


First of all, the lift (.27933) quoted on the Cam Doctor's first exhaust camsahft seems inconsistent with a 1mm increase in lift over the intake lift, in fact it is a smidge lower.

The second interesting statistic here is the "Lobe Area" given in IN*DEG. I would have to guess that is the integral of of the cam lift curve in polar coordinates. In effect, it is the summation of the area of camshaft lift over time (as measured by crankshaft rotation), and thus has a linear equivalancy to the total valve opening over time (area of opening multiplied by degrees of crankshaft rotation).. If this is a true representation of the stock intake cam and the performance intake cam, then the performance camshaft has a little more than 15% increase in total opening area over time. Given that the lift is only 11% more, and the duration is only 3.1% more, it would seem that the performance cam is either spending a slightly disproportionate amount of time fully open, or is opening on a slightly steeper ramp than the stock camshaft. Any comments?

Still don't understand the discrepancy with the quoted stock exhaust
camshaft specs.

The figure you mention also has me confused even though I analyzed and compared everything, as you will find way back in the thread. I can not see how the figure could apply as you suggest, as the cam grinders would not have had information relative to valve area. You will not that the word area is shown with inverted commas, 'area' and probably should not be taken literally. In point of fact I have calculated the improvement in valve open area as a result of the increase in lift and related this to time, but have not looked at the overall affect that you mention. This is an interesting exercise.

I wonder if the figure is an indication of the degrees when the valve should be virtually fully open, i.e. top of the cam lobe. If so the figure appears on the high side but in any event could only be arbitrary. There are others here who may understand the cam grinders teminology and possibly could assist.

My figures and comments back in the thread, will be of help in understanding the discrepacies which I think you have found confusing. Different methods of measurement apply between grinder and OEM.

[oab_au]

This was the analysis of the camshafts posted by Bill (SVXRide) a few pages ago.

http://www.subaru-svx.net/photos/files/SVXRide/35887.jpg

According to Chike"s original post:


First of all, the lift (.27933) quoted on the Cam Doctor's first exhaust camsahft seems inconsistent with a 1mm increase in lift over the intake lift, in fact it is a smidge lower.

The second interesting statistic here is the "Lobe Area" given in IN*DEG. I would have to guess that is the integral of of the cam lift curve in polar coordinates. In effect, it is the summation of the area of camshaft lift over time (as measured by crankshaft rotation), and thus has a linear equivalancy to the total valve opening over time (area of opening multiplied by degrees of crankshaft rotation).. If this is a true representation of the stock intake cam and the performance intake cam, then the performance camshaft has a little more than 15% increase in total opening area over time. Given that the lift is only 11% more, and the duration is only 3.1% more, it would seem that the performance cam is either spending a slightly disproportionate amount of time fully open, or is opening on a slightly steeper ramp than the stock camshaft. Any comments?

Still don't understand the discrepancy with the quoted stock exhaust camshaft specs.


Yes that is the way the lobe area is stated. Its a real bell curve, I'll see if I can find a Diag.

The only things that we did know about the cams, was the factory lift, that Todd measured. The 1mm lift and the duration was quoted to Chike by Scott at Delta. That was all I had to go on.

The lobe area is affected more by the lift, than the small duration increase. The lift is not just an increase in maximum lift, it is an increase in the lift at all points of the cams rotation. As almost the same duration is used, the valve must accelerate faster to reach the higher lift, than it did before, in the same rotational time. The end result of this, is that the bell curve becomes wider as it grows.

The other point is, that the profile that delta used was a slow opening, profile, against the faster opening profile that the EG33 uses.

No I don't know what the exhaust numbers are either, we didn't look at the exhaust at all, as changing the exhaust cams is a bigger job than just the inlets. Whats this mean Bill?

Harvey.;)

[Trevor]

Harvey,

A diagram will in no way explain the basic facts. However, your ploy has gained you the opportunity to undertake the necessary research.

The following explanation has not been lifted from a text book, as you will no doubt claim, but I have leaned on a friend for assistance with the basics. I am confident that my wording is accurate.

A value specified as cam lobe area, is expressed/specified as inch degree units. The figure is calculated on the basis of, the summation of the duration X lift at each degree. (N.B. At each degree and this indicates the means of establishing increments.)

The figure is usually used as a method of comparing cams lobe to lobe, one against another. However it is not often included with the more usual specifications.

It is the use of the word "area" which has caused confusion. Just how this has been applied on the basis of logic, is hard to fathom. Surely "cam lobe rate" or whatever, would be more appropriate and descriptive.

Harvey, I am now confident of a barrage of scanned stuff designed to impress, bury this quite short summation and restore the thread to pandemonium. Go to it ! :D

[shotgunslade]

Trevor:

The In-Deg measure is an area, except that it is in polar coordinates rather than Cartesian coordinates. How you described it, the summation of the lift at each degree of rotation is in fact the same as the integral of the cam lobe profile in polar coordinates. The actual valve opening is a cylindrical surface with a height equal to the cam lift times the leverage of rocker arms, if any, and a circumference equal to that of the valve seat, since all of these quantities are constants except for the cam lift, the total valve opening area integrated over time (defined as crankfshaft rotation) is linearly proportional to the cam lobe lift area. So the In-Deg measure tells you how much valve opening you have, relative to other cams. The In-Deg measure is a function not only of the lift, which is the max height of the cam lobe profile, but also of the length and shape of the curve. What I was pointing out was that if you multiply the increase in lift (11%) times the increase in duration (3.1%), you only get a 14.4% increase in area, whereas the actual increase is 15.1%, which is consistent with the performance cam adding its increased duration at near full lift, rather than by having an extended and less steep initial lift profile. It may be that the performance cam initially has a relatively slow lift up to 0.05 in, but after that it must have a lift rate comparable to the stock cam, in order to achieve the In-Deg measure. At the end of the day, a 15% increase in the time-integrated valve opening area is not insignificant. I can't comment on the impact of all this on the sonic wave, but it certainly will increase the amount of mixture flow at a given pressure differential.

[SVXRide]

Yes that is the way the lobe area is stated. Its a real bell curve, I'll see if I can find a Diag.

The only things that we did know about the cams, was the factory lift, that Todd measured. The 1mm lift and the duration was quoted to Chike by Scott at Delta. That was all I had to go on.

The lobe area is affected more by the lift, than the small duration increase. The lift is not just an increase in maximum lift, it is an increase in the lift at all points of the cams rotation. As almost the same duration is used, the valve must accelerate faster to reach the higher lift, than it did before, in the same rotational time. The end result of this, is that the bell curve becomes wider as it grows.

The other point is, that the profile that delta used was a slow opening, profile, against the faster opening profile that the EG33 uses.

No I don't know what the exhaust numbers are either, we didn't look at the exhaust at all, as changing the exhaust cams is a bigger job than just the inlets. Whats this mean Bill?

Harvey.;)


Harvey,
If memory serves me right, the "exhaust" info is a function of the software being designed primarily to be used with cams for single cam engines (i.e. exhaust and intake lobes on the same camshaft). I'm probably going to contact Scott sometime in the near future to look into having a set of intake cams cut to our exhaust profile (he already has one of my sets of exhaust cams to take direct measurements off of), so let me know if you have any specific questions you want me to bring up with him.
-Bill

[SVXRide]

Trevor:

The In-Deg measure is an area, except that it is in polar coordinates rather than Cartesian coordinates. How you described it, the summation of the lift at each degree of rotation is in fact the same as the integral of the cam lobe profile in polar coordinates. The actual valve opening is a cylindrical surface with a height equal to the cam lift times the leverage of rocker arms, if any, and a circumference equal to that of the valve seat, since all of these quantities are constants except for the cam lift, the total valve opening area integrated over time (defined as crankfshaft rotation) is linearly proportional to the cam lobe lift area. So the In-Deg measure tells you how much valve opening you have, relative to other cams. The In-Deg measure is a function not only of the lift, which is the max height of the cam lobe profile, but also of the length and shape of the curve. What I was pointing out was that if you multiply the increase in lift (11%) times the increase in duration (3.1%), you only get a 14.4% increase in area, whereas the actual increase is 15.1%, which is consistent with the performance cam adding its increased duration at near full lift, rather than by having an extended and less steep initial lift profile. It may be that the performance cam initially has a relatively slow lift up to 0.05 in, but after that it must have a lift rate comparable to the stock cam, in order to achieve the In-Deg measure. At the end of the day, a 15% increase in the time-integrated valve opening area is not insignificant. I can't comment on the impact of all this on the sonic wave, but it certainly will increase the amount of mixture flow at a given pressure differential.

Dan,
Nicely stated! Now, when are you going to get that CFD model done so we can see what the impact is on the sonic wave;) :D Come on, you VP-kinda guy, you can make it happen!:D
-Bill

[shotgunslade]

Bill:
The sonic pressure wave can only be captured in a dynamic time-sequence compressible flow simulation. That really is rocket science, not air conditioning. I had planned, and still plan to get a steady state non-compressible simulation of the vortex activity in the snorkus, realizing that it really isn't a steady state flow field. The intent was to shown the extent of large scale turbulence, not necessarily show its exact configuration, as that configuration would likely change in a chaotic manner not only with constant flow into and out of the domain, but would be even more variable with the pulsating flow driven by intake valve operation. If I can just get rid of some of these paying projects, I could get a little machine time for a true boondoggle. Oh well, we have to do what we get paid to do.

[SVXRide]

Bill:
The sonic pressure wave can only be captured in a dynamic time-sequence compressible flow simulation. That really is rocket science, not air conditioning. I had planned, and still plan to get a steady state non-compressible simulation of the vortex activity in the snorkus, realizing that it really isn't a steady state flow field. The intent was to shown the extent of large scale turbulence, not necessarily show its exact configuration, as that configuration would likely change in a chaotic manner not only with constant flow into and out of the domain, but would be even more variable with the pulsating flow driven by intake valve operation. If I can just get rid of some of these paying projects, I could get a little machine time for a true boondoggle. Oh well, we have to do what we get paid to do.

Dan,
Sure, so you're saying I'm the one who has to do this:rolleyes: :D
My vote is for the "true boondoggle"!!:cool:
-Bill

[oab_au]

Dan this is the diagram. of the cam lobes that the SVX has. At the standard lift and duration.
http://www.subaru-svx.net/photos/files/oab_au/37203.jpg
If you look at the 5 mm lift position of the 8 mm exhaust lobe opening, at the 180* point, and compair it to the 5 mm lift position of the closing inlet 7 mm lobe, at the 540* you can see that the 8 mm lift exhaust is wider, than the 7 mm lift inlet.
The rate of lift, of the 8 mm is faster than the 7 mm lift. This is where the increase in lobe area comes from.

Harvey.;)

[dynomatt]

Good diagram Harvey. Is this "properly" measured or taken from other content?

I'm getting the same done to mine this weekend (along with some flow testing) so it will be interesting to compare.

M

[oab_au]

Good diagram Harvey. Is this "properly" measured or taken from other content?

I'm getting the same done to mine this weekend (along with some flow testing) so it will be interesting to compare.

M

Hi Matt it is taken from a simulation of the SVX lift and duration figures, that I know of. Assuming the cam is a fast opening pollydyne profile, that seem to be borne out by the lift/degree figures, that Mychailo got from Scott at Delta.

Harvey.;)

[Trevor]

Trevor:

The In-Deg measure is an area, except that it is in polar coordinates rather than Cartesian coordinates. How you described it, the summation of the lift at each degree of rotation is in fact the same as the integral of the cam lobe profile in polar coordinates. The actual valve opening is a cylindrical surface with a height equal to the cam lift times the leverage of rocker arms, if any, and a circumference equal to that of the valve seat, since all of these quantities are constants except for the cam lift, the total valve opening area integrated over time (defined as crankfshaft rotation) is linearly proportional to the cam lobe lift area. So the In-Deg measure tells you how much valve opening you have, relative to other cams. The In-Deg measure is a function not only of the lift, which is the max height of the cam lobe profile, but also of the length and shape of the curve. What I was pointing out was that if you multiply the increase in lift (11%) times the increase in duration (3.1%), you only get a 14.4% increase in area, whereas the actual increase is 15.1%, which is consistent with the performance cam adding its increased duration at near full lift, rather than by having an extended and less steep initial lift profile. It may be that the performance cam initially has a relatively slow lift up to 0.05 in, but after that it must have a lift rate comparable to the stock cam, in order to achieve the In-Deg measure. At the end of the day, a 15% increase in the time-integrated valve opening area is not insignificant. I can't comment on the impact of all this on the sonic wave, but it certainly will increase the amount of mixture flow at a given pressure differential.


Your use of the word "Cartesian" will throw some, but In brief what you are saying is, that the figure should be understood as relating to valve opening area rather than cam/valve movement, the two being directly related, and that the figure gives a more accurate assessment than that arrived at using the more usual valve specifications.

As a result I now understand why the word "area" is used and that the specifics I have stated still apply.

Thank you, Trevor.

[oab_au]

Dan you are using the term "valve area" to describe the Lobe area. The Valve area is related to the valve size, this is not included in the cam specifications. This has thrown Trevor into a different area all together, and is probably:confused: yet again.

Lobe area is the area shown in the diagram, that only relates to lift and duration. Also known as 'under lobe area'.

Harvey.;)

[Trevor]

Dan you are using the term "valve area" to describe the Lobe area. The Valve area is related to the valve size, this is not included in the cam specifications. This has thrown Trevor into a different area all together, and is probably:confused: yet again.

Lobe area is the area shown in the diagram, that only relates to lift and duration. Also known as 'under lobe area'.

Harvey.;)

Harvey, it is you who is confused not I. :confused: I have been thrown no where. :rolleyes:

The size of the valve is accepted as being not relevant. The relevant measurement is the valve open area and the relative change in this dimension. Try again. :p

[Phast SVX]

If i amcorrect in saying that the overlap in the SVX engine is definetly not excessive, reducing overlap and increasing duration further would increase drivability issues 10 fold. As far as i can tell, with a mostly stock motor and a daily driver in mind, why not just increase lift and fit some larger valves(with the complimentary head work)? My experience with excessive duration and decreased overlap in EFI standalone vehicles is widowmaking to tune for a professional ;)

What is EFD in our setup?
phil

[Trevor]

I will be looking at doing cams for my engine rebuild and was wondering if there are any suggestions for modifications with a boosted engine (15-20 psi) running 8.5:1 compression. Great thread by the way.

Thanks

Chuck D.

Satisfaction may have been gained on the ego front, but the thread has been taken completely OT and sadly the original request by Chuck, as above, has not been satisfactorily answered, much to the discredit of all.

Harvey has put forward proposals towards increased overlap and others have pointed out that this is the wrong approach. I have agreed accordingly, as well as pointing out the advantages of retaining the OEM cams. Harvey has not withdrawn his statements, so that it is necessary to clarify what is in fact correct, otherwise Chuck is left in limbo.

To this end I have done a quick google in search of evidence. It took very little to turn up confirmation regarding the points I have put forward and at the same time negate those proposed by Harvey. This evidence will be found here:-

http://www.mx6.com/forums/archive/index.php/t-135425.html

P.S. The link within is also worth a look and is better presented with more detail.

http://www.mx6.com/forums/showthread.php?t=135425

[shotgunslade]

Trevor:
Area in polar coordinates would have the unit of In-Deg. Area in Cartesian coordinates would have the units of square inches.

Harvey:

I was relating the lobe lift area over time to the actual valve opening area over time as the valve seat diameter is assumed to be constant between the cam alternatives we are discussing. Thank you for the diagrams. Although it seems they compare the the SVX exhaust cam with the SVX intake cam rather than the 240SX intake cam that I had installed in my car. It would be interesting to find the actual "lobe area" number for the SVX exhaust cam, as this number is very important in determing the actual flow potential of the camshaft.

Trevor:

The above comments do not diminish the importance of the dynamics of the flow, the management of the sonic wave and the interaction of intake and exhaust overlap with respect to those dynamics, but only discuss how much opening for how long is available to pull mixture through (for NA) or push mixture through (for FD).

Is this what they call shuttle diplomacy?

[Trevor]

Trevor:
Area in polar coordinates would have the unit of In-Deg. Area in Cartesian coordinates would have the units of square inches.

Harvey:

I was relating the lobe lift area over time to the actual valve opening area over time as the valve seat diameter is assumed to be constant between the cam alternatives we are discussing. Thank you for the diagrams. Although it seems they compare the the SVX exhaust cam with the SVX intake cam rather than the 240SX intake cam that I had installed in my car. It would be interesting to find the actual "lobe area" number for the SVX exhaust cam, as this number is very important in determing the actual flow potential of the camshaft.

Trevor:

The above comments do not diminish the importance of the dynamics of the flow, the management of the sonic wave and the interaction of intake and exhaust overlap with respect to those dynamics, but only discuss how much opening for how long is available to pull mixture through (for NA) or push mixture through (for FD).

Is this what they call shuttle diplomacy?

For some reason you are assuming that I do, not understand all of what you have have been saying. This is not the case and repetition of that which is obvious is therefore not required.

Thanks anyway, Trevor.

P.S. Would It be correct to address you as " Dan"?

[oab_au]

Your use of the word "Cartesian" will throw some, but In brief what you are saying is, that the figure should be understood as relating to valve opening area rather than cam/valve movement, the two being directly related, and that the figure gives a more accurate assessment than that arrived at using the more usual valve specifications.

As a result I now understand why the word "area" is used and that the specifics I have stated still apply.

Thank you, Trevor.

Yes, I see you have come back 20 minuits later, to edit out your confused part.

Harvey.;)

[oab_au]

If i amcorrect in saying that the overlap in the SVX engine is definetly not excessive, reducing overlap and increasing duration further would increase drivability issues 10 fold. As far as i can tell, with a mostly stock motor and a daily driver in mind, why not just increase lift and fit some larger valves(with the complimentary head work)? My experience with excessive duration and decreased overlap in EFI standalone vehicles is widowmaking to tune for a professional ;)

What is EFD in our setup?
phil

Phil, to try to reduce the overlap, while increasing the duration, would mean
moving the cams lobe centres. The inlet would have to close late, and the exhaust would have to open early.
I tend to think this would be advantageous only at higher boost and engine rpms. Remembering that you don't have boost at low rpms, you would have to use the stick to keep the rpms up in the boost range.

I might have to get Rob to decipher your Madison slang.:D "widowmaking to tune for a professional ", is that good or bad? and, If I knew what "EFD" was I'd have a look.:D

Harvey.;)

[Trevor]

Yes, I see you have come back 20 minuits later, to edit out your confused part.

Harvey.;)

Harvey, your insinuations are reveal your nature. The fact is that having had further thoughts and as a result misgivings regarding my wording, I inserted the word "valve" which in no way altered the context but clarified and reinforced my intended meaning.

I have in the past been in anticipation of your ploy, now confirmed, and as a result have been marking any edit accordingly. In this instance the mechanics would have been tedious. I leave you to also misconstrue this statement in your quest for perceived authority. :(

You appear hell bent on trying to discredit my honesty. You would be well advised to uphold yours, by owning up to your errors, exemplified in the post which as usual you are endeavoring to bury. Are we expected to continue to believe that a turbo charged engine will benefit as a result of increased overlap? :confused: :p

[oab_au]

Satisfaction may have been gained on the ego front, but the thread has been taken completely OT and sadly the original request by Chuck, as above, has not been satisfactorily answered, much to the discredit of all.

Harvey has put forward proposals towards increased overlap and others have pointed out that this is the wrong approach. I have agreed accordingly, as well as pointing out the advantages of retaining the OEM cams. Harvey has not withdrawn his statements, so that it is necessary to clarify what is in fact correct, otherwise Chuck is left in limbo.

To this end I have done a quick google in search of evidence. It took very little to turn up confirmation regarding the points I have put forward and at the same time negate those proposed by Harvey. This evidence will be found here:-

http://www.mx6.com/forums/archive/index.php/t-135425.html

P.S. The link within is also worth a look and is better presented with more detail.

http://www.mx6.com/forums/showthread.php?t=135425

Trevor, go back to here:http://www.subaru-svx.net/forum/showpost.php?p=416522&postcount=126 and tell me where I have told Chuck to use increased overlap.:rolleyes:

If you are going to google up evidence, make sure it applies to the same type of engine. You are compairing two valve cams to four valve cams.

Harvey.;)

[Trevor]

If i amcorrect in saying that the overlap in the SVX engine is definetly not excessive, reducing overlap and increasing duration further would increase drivability issues 10 fold. As far as i can tell, with a mostly stock motor and a daily driver in mind, why not just increase lift and fit some larger valves(with the complimentary head work)? My experience with excessive duration and decreased overlap in EFI standalone vehicles is widowmaking to tune for a professional ;)

What is EFD in our setup?
phil

Yes Phil, you are absolutely correct in assuming that the overlap relative to the OEM SVX engine is not excessive.

You must also take into account that the OEM engine as produced, incorporates maximum valve area and the inlet tract is difficult to improve in any worthwhile manner. The Subaru engineers have done an excellent job in providing maximum efficiency, allied with drive-ability. In any event, your observations are valid.

Increased overlap is normally a factor part and parcel with increasing duration, in respect of mods to increase power at higher R.P.M. There appears to be possibly some confusion in this regard.

"Widowmaker" was an apt term I once heard used with reference to a machine incorporating a high speed cutting wheel. :D

[Trevor]

Trevor, go back to here:http://www.subaru-svx.net/forum/showpost.php?p=416522&postcount=126 and tell me where I have told Chuck to use increased overlap.:rolleyes:

If you are going to google up evidence, make sure it applies to the same type of engine. You are compairing two valve cams to four valve cams.

Harvey.;)

Harvey these are your words by way of a recommendation :-

"With this in mind, I would only fit inlet cams ground on the 8mm lift/244* exhaust profile. The extra lift won't affect the low end, but will benefit the mid/top end, where the breathing tapers off."

Specifically, the fitting of inlet cams ground to the exhaust profile would increase overlap. This suggestion of increasing overlap brought worth much following comment.

The principals outlined in the article I put forward apply in respect any mechanical valve arrangement and are in no way confined. To state otherwise is stupid.

[TomsSVX]

I get the feeling that this really needs to be said. While many of you are pouring out information of what would be the right grind for the cams I find more than anyting is that Trevor and Harvey are more or less bickering and arguing. Listen, I understand you two are not on the best of terms but please try to be reasonably civil in regards to your statements. More often than not I pass over a post that looks like it could be another attack on the other even when it could hold possibly important information. I mearly ask that you put your differences aside here and work for the greater cause

Tom

[Trevor]

I get the feeling that this really needs to be said. While many of you are pouring out information of what would be the right grind for the cams I find more than anyting is that Trevor and Harvey are more or less bickering and arguing. Listen, I understand you two are not on the best of terms but please try to be reasonably civil in regards to your statements. More often than not I pass over a post that looks like it could be another attack on the other even when it could hold possibly important information. I mearly ask that you put your differences aside here and work for the greater cause

Tom

Yes Tom,

I for one will comply, on the understanding that information is put forward as the opinion of the author, rather than as absolute fact. Otherwise those non technical, are persuaded to accept that which can be in error, on the basis of perceived authority. My sole intent has been to prevent this tendency.

Sincere thanks, Trevor.

[shotgunslade]

Trying to understand all that has been said, and adding a little bit of my own, I would try to summarize the thread as follows. In general, for NA engines, having more lift area (IN-DEG) will permit more mixture to get into the cylinder. Longer duration and greater overlap will tend to lower torque at low RPM, while raising high rpm horsepower, up to a point. For FD engines, overlap is not recommended, and thus, by geometry, duration is limited. Higher lift is not as useful as in NA engines, but is of some benefit, and, because duration is limited, must be achieved by steeper lramps for lifting and closing, which is OK as long as the ramps and curve transitions are not so steep and abrupt as to encourage excessive valve lifting forces and valve bounce at high rpm's.

Please note that I am trying to understand, and to the extent that I am redundant, it is only to make these issues clear to myself. Also, I have no vested interest in any particular piece of information, and am only trying to find out what is right. If I am wrong in any of these assertions, please correct me in a civil fashion, so that I may learn. Thank you.

[oab_au]

I get the feeling that this really needs to be said. While many of you are pouring out information of what would be the right grind for the cams I find more than anyting is that Trevor and Harvey are more or less bickering and arguing. Listen, I understand you two are not on the best of terms but please try to be reasonably civil in regards to your statements. More often than not I pass over a post that looks like it could be another attack on the other even when it could hold possibly important information. I mearly ask that you put your differences aside here and work for the greater cause

Tom

Tom it could have been a good thread that you started. But after 160 posts, 25% have merit, the rest are absolute crap. I find it pointless writing information, then spending the next 2 pages defending my writing.

I don't care personally if what I write, is perceived as fact or fiction, that is up to the reader, but I don't need personal attacks in every reply.

I find it is pointless to keep writing to this thread, under these conditions, as it has been turned into a debacle.

Harvey.;)

[Trevor]

Trying to understand all that has been said, and adding a little bit of my own, I would try to summarize the thread as follows. In general, for NA engines, having more lift area (IN-DEG) will permit more mixture to get into the cylinder. Longer duration and greater overlap will tend to lower torque at low RPM, while raising high rpm horsepower, up to a point. For FD engines, overlap is not recommended, and thus, by geometry, duration is limited. Higher lift is not as useful as in NA engines, but is of some benefit, and, because duration is limited, must be achieved by steeper lramps for lifting and closing, which is OK as long as the ramps and curve transitions are not so steep and abrupt as to encourage excessive valve lifting forces and valve bounce at high rpm's.

Please note that I am trying to understand, and to the extent that I am redundant, it is only to make these issues clear to myself. Also, I have no vested interest in any particular piece of information, and am only trying to find out what is right. If I am wrong in any of these assertions, please correct me in a civil fashion, so that I may learn. Thank you.

Your summery is exactly correct and for sure you having nothing to learn. Most certainly you are far from redundant. The post is much appreciated.

Thank YOU, Trevor.

[TomsSVX]

Well guys can we seriously come up with a couple agreeable stats then??

1. N/A mild grind for those looking for a little more
2. N/A aggressive grind for those looking to make a serious machine
3. FI turbo grind for those turbo builders
4. FI S/C grind for those purchasing LAN's Stage 3 or going with a homegrown S/C like svxfiles??

I mean, this should not be too much to ask and that is what this thread is really all about

Tom

[Trevor]

Well guys can we seriously come up with a couple agreeable stats then??

1. N/A mild grind for those looking for a little more
2. N/A aggressive grind for those looking to make a serious machine
3. FI turbo grind for those turbo builders
4. FI S/C grind for those purchasing LAN's Stage 3 or going with a homegrown S/C like svxfiles??

I mean, this should not be too much to ask and that is what this thread is really all about

Tom


Tom,

Way back in the thread, i.e. my post No. 69 dated 5/23/06, the following was included covering much detail. The information gained no response and was quickly buried among the trivia and self promoting lectures. It is interesting that those who publish the claim of expert status, have been unwilling to risk putting their reputation on the line accordinly.:( ]These suggestions remain as my answer in respect to items 1 & 2. The thread contains no other positive information I agree and hence your plea.

Quote from way back in the thread. --------- Going for the reasonable maximum and to make a real difference, I will stick my neck out and suggest:-

Based on Grinders Measurements:-

Duration: 202, Opening 24, ATDC, Closing 46 ABDC.

Edit. I think you could go as far as say:- 210, 20, 50.

Based on Usual Measurements:-

Duration; 260, Opening 5, BTDC, Closing 75 ABDC.

Edit :- 268, 9, 79

Are there any takers ? -----------

The above figures apply only in respect of a NA engine. With reference to forced induction, i.e. items 3 & 4, as previously I say, all things considered, stick with the OEM cams.

My opinion regarding lift for reasons as previously stated, is towards confining any increase to 0.8 mm, unless further practical tests are forthcoming, involving continued operation and which can prove reliability.

I continue your plea and request that there should not be another OT lecture. :)

Edit. P.S. The exhaust timing, which has more or less been ignored within the thread, should also be considered as a complimentary issue. Considering the time and work involved in changing the cams, it would appear cost effective to alter the exhaust cams together with the inlet. A similar amount of relative increase in opening, on a percentage basis, could be applied.

Edit P.P.S. As a result of previous insinuations, I point out that the "edit" figures included within the quoted text, are part of the original.

As I have previously pointed out a final decision is up to the individual, who is the one spending the money and the only one able to define the exact requirements. Making this decision is part and parcel of the fun involved in the exercise. ;)

[TomsSVX]

Thank you. With all the info in this thread I am sure someone could put all the pieces together but there is too much clutter. I also agree that if you are in there, an agreeable set of exhaust cams should be used in order to keep time consumed doing the job to a minimum.

In regard to FI would you not recommend a slight decrease in duration while leaving lift the same?? I am looking to be running 12lbs of boost at first with the Stage 3 and I will be looking to build a full motor over the next few years in order to run ~20lbs. So cams and valve springs will be investigated as well. Thank you for your time, patience, and information

Tom

[Trevor]

Thank you. With all the info in this thread I am sure someone could put all the pieces together but there is too much clutter. I also agree that if you are in there, an agreeable set of exhaust cams should be used in order to keep time consumed doing the job to a minimum.

In regard to FI would you not recommend a slight decrease in duration while leaving lift the same?? I am looking to be running 12lbs of boost at first with the Stage 3 and I will be looking to build a full motor over the next few years in order to run ~20lbs. So cams and valve springs will be investigated as well. Thank you for your time, patience, and information

Tom

Yes, a decrease in duration should be considered, but you must take into account costs/labour/benefit. Refer the article I posted. All the basic principals outlined there apply, no matter what valve arrangement is involved, including rotary or sleeve !

Edit P.S. Sorry, I did not acknowledge your thanks. At the moment I am inclined to be terse as a result of this frustrating thread. Sincerely, Trevor.

[oab_au]

Well guys can we seriously come up with a couple agreeable stats then??

1. N/A mild grind for those looking for a little more
2. N/A aggressive grind for those looking to make a serious machine
3. FI turbo grind for those turbo builders
4. FI S/C grind for those purchasing LAN's Stage 3 or going with a homegrown S/C like svxfiles??

I mean, this should not be too much to ask and that is what this thread is really all about

Tom

Yes Tom, not a big ask.:D

1. N/A mild grind for those looking for a little more

To answer this Tom, I have to go back to what I purposed in this thread, in 11/05.
http://www.subaru-svx.net/forum/showpost.php?p=351096&postcount=164
The stage one turned out to be on the ball. The only change would be to use the standard SVX exhaust profile 244* at 8mm lift, instead of the Nissan one, for the reasons stated here.
http://www.subaru-svx.net/forum/showpost.php?p=372024&postcount=4

2. N/A aggressive grind for those looking to make a serious machine.

Tom this would be the stage 2/3 that I purposed. Since then we have found a obtainable profile that Delta has, that would fill this request. Its the S14 KA24DE that Mychailo purposed here.
http://www.subaru-svx.net/forum/showpost.php?p=372032&postcount=5
About 257* duration, 8 75mm lift on both inlet and exhaust. I have used these in a simulation, and found it to produce strong torque to 7000 rpm. This set would suit most road applications.
For the extremist like Dynomat, we need about 260* .at 9mm lift, on both inlet and exhaust. But this would need a lot of serious engine work to work well, and would be for racing mainly, running into the 8000 rpm mark. I haven’t looked for a set of profiles for this, so can’t say what we could use.

3. FI turbo grind for those turbo builders
4. FI S/C grind for those purchasing LAN's Stage 3 or going with a homegrown S/C like svxfiles??

These really have to be grouped differently. The Turbo and the centrifugal needs, are different to the Positive displacement supercharger.

The Positive displacement supercharger fitting removes the IRIS, but as it produces boost at low rpms, it will still have torque at these rpms. All the blown engines will benefit from the same cam as N/A 1. Just more lift on the inlet, to allow the torque to continue up the rev range, which will increase the final HP.

The Turbo, and Centrifugal like Tomfiles, can use the same NA 1. cam, to increase the top end, but as they lack boost below 2500/3000, rpm? the low end torque needs to be retained, as much as possible, which means retaining the IRIS, depending on gearing used.

The exhaust for the forced induction, will be OK, till the boost is up around 1.bar. At this point the lift may need increasing to prevent exhaust pressure building up to enter the inlet on overlap. The exhaust valve, which should be Sodium filled, needs to spend as much time on the seat as possible to cool it. So I would not increase the exhaust duration.

The Turbo at higher boost needs the same treatment. The lobe center may need advancing to alter the header pipe pressure, but I don’t have enough experiences with Turbos to say.

Harvey.;)

[SVXRide]

Yes Tom, not a big ask.:D



2. N/A aggressive grind for those looking to make a serious machine.

Tom this would be the stage 2/3 that I purposed. Since then we have found a obtainable profile that Delta has, that would fill this request. Its the S14 KA24DE that Mychailo purposed here.
http://www.subaru-svx.net/forum/showpost.php?p=372032&postcount=5
About 257* duration, 8 75mm lift on both inlet and exhaust. I have used these in a simulation, and found it to produce strong torque to 7000 rpm. This set would suit most road applications.
For the extremist like Dynomat, we need about 260* .at 9mm lift, on both inlet and exhaust. But this would need a lot of serious engine work to work well, and would be for racing mainly, running into the 8000 rpm mark. I haven’t looked for a set of profiles for this, so can’t say what we could use.


Harvey.;)

Harvey,
Thanks for the summary!:cool: Just to keep everything in this thread, the KA24DE cam referenced is the KA24DE exhaust cam profile that we'd use for our intake cams, correct? Question, how does the ramp profile compare with our existing intake cam lobes? Any potential issues with our hydraulic lifters/followers? Based on your simulation work, is there really any "down" side to the use of this profile other than a potential for reduced mpg because we'll be "in" the throttle so much (grinning all the time!):D
Last question -- I'm taking it - based on your summary - that we're best off leaving the exhaust cams alone?
Thanks.
-Bill (wondering if anyone is interested in buying a set of new, still in the box, SVX intake cams ground to the initial Stage 1 profile....)

[Nemesis Destiny]

-Bill (wondering if anyone is interested in buying a set of new, still in the box, SVX intake cams ground to the initial Stage 1 profile....)I'd be interested, once I get a 6MT installed. How much?

[TomsSVX]

Bill, I will take em... How fast can you get them here?? I would like to fly them out to SD with me to install in Gest24's car as a little gift for his hospitality while I am there. Plus we will have the engine out anyway

Tom

[SVXRide]

Bill, I will take em... How fast can you get them here?? I would like to fly them out to SD with me to install in Gest24's car as a little gift for his hospitality while I am there. Plus we will have the engine out anyway

Tom


Nemesis,
I know you posted before Young Tom, but he had actually talked to me about buying them from me over a month ago, so I'm going to honor his already stated interest. Hope you understand.

Tom,
Give me a call sometime in the afternoon/evening on Sunday (oh, that's right, it's already Sunday:rolleyes: ). I'm going to be sandblasting/glassbeading SVX "stuff" down at the lower garage, so it might take a try or two to get me on my cell.

-Bill

[Nemesis Destiny]

Yeah, that's fine. I'm sure he'll probably put them to better use than I could anyway. And sooner.

[SVXRide]

Yeah, that's fine. I'm sure he'll probably put them to better use than I could anyway. And sooner.

Nemesis,
Thanks for understanding!

Tom,
I dropped you a PM with phone # info....
-Bill

[oab_au]

Bill and all, there is nothing wrong with the early cams. They will still put a smile on your face.:)
I don't here any complaints from the uses. If pushed to the select one to the other, I'd take the exhaust ones.

Harvey.;)

[oab_au]

Harvey,
Thanks for the summary!:cool: Just to keep everything in this thread, the KA24DE cam referenced is the KA24DE exhaust cam profile that we'd use for our intake cams, correct? Question, how does the ramp profile compare with our existing intake cam lobes? Any potential issues with our hydraulic lifters/followers? Based on your simulation work, is there really any "down" side to the use of this profile other than a potential for reduced mpg because we'll be "in" the throttle so much (grinning all the time!):D
Last question -- I'm taking it - based on your summary - that we're best off leaving the exhaust cams alone?
Thanks.
-Bill (wondering if anyone is interested in buying a set of new, still in the box, SVX intake cams ground to the initial Stage 1 profile....)

As far as the original Delta grind goes. I don't know what it was taken from. I think it was from a KA24DE of some year? Mychailo may know what is was from.

The cams that I suggested for the NA2. are these:
S14 KA24DE motor (late model 240SX)
intake profile: 0.350" lift, 206 deg @ 0.050" (a bit too much duration)
exhaust profile: 0.350" lift, 200 deg @ 0.050" (almost too much duration, but probably ok).

that Mychailo found. They just fit the specifications that I was looking for.

The profiles ramps don't account for much timing, as it is all over by 0.020" lift. This is more to do with the type of lifters that are used. That said, I prefer that the opening ramps are fast opening, hydraulic ramps, to provide a strong sonic wave action. The hydraulic lifters are a bit heaver than solids, but they handle valve bounce better, as they just pump up to level out the rpms, and protect the engine.

The only real downside to the NA2. set would be a loss of some low engine speed torque from the IRIS. The NA1. set has no downside.

The exhaust cam won't need changing for the NA1. set. The NA2 set will raise the engine rpms, so the exhaust cam has to be changed also, to suit the higher rpms.

The forced engines may need changes as I have outlined.

Harvey.;)

[SVXRide]

As far as the original Delta grind goes. I don't know what it was taken from. I think it was from a KA24DE of some year? Mychailo may know what is was from.

The cams that I suggested for the NA2. are these:
S14 KA24DE motor (late model 240SX)
intake profile: 0.350" lift, 206 deg @ 0.050" (a bit too much duration)
exhaust profile: 0.350" lift, 200 deg @ 0.050" (almost too much duration, but probably ok).

that Mychailo found. They just fit the specifications that I was looking for.
*snip*

The only real downside to the NA2. set would be a loss of some low engine speed torque from the IRIS. The NA1. set has no downside.

The exhaust cam won't need changing for the NA1. set. The NA2 set will raise the engine rpms, so the exhaust cam has to be changed also, to suit the higher rpms.

*snip*

Harvey.;)

Harvey,
Thanks. So, if I understand things correctly, NA1 consists of the stock intake reground using the stock exhaust cam profile used with the stock exhaust cams. NA2 consists of regrinding the stock intake and exhaust to the respective KA24DE profiles. Yes? Can you quantify the "a bit too much duration" comment on the intake cam?
Thanks again.
-Bill

[oab_au]

Harvey,
Thanks. So, if I understand things correctly, NA1 consists of the stock intake reground using the stock exhaust cam profile used with the stock exhaust cams. NA2 consists of regrinding the stock intake and exhaust to the respective KA24DE profiles. Yes? Can you quantify the "a bit too much duration" comment on the intake cam?
Thanks again.
-Bill

Yes the NA1 cam is the SVX exhaust profile ground on to the standard SVX inlet cam.

Yes. the NA2 cams are these specifications, ground on to the SVX inlet and exhaust cams.

S14 KA24DE motor (late model 240SX)
intake profile: 0.350" lift, 206 deg @ 0.050"
exhaust profile: 0.350" lift, 200 deg @ 0.050"


Can you quantify the "a bit too much duration" comment on the intake cam? Bill that was Mychailo's comments, that I cut and pasted.:)
I think it will be fine.:)

Harvey.;)

[SVXRide]

Yes the NA1 cam is the SVX exhaust profile ground on to the standard SVX inlet cam.

Yes. the NA2 cams are these specifications, ground on to the SVX inlet and exhaust cams.

S14 KA24DE motor (late model 240SX)
intake profile: 0.350" lift, 206 deg @ 0.050"
exhaust profile: 0.350" lift, 200 deg @ 0.050"


Can you quantify the "a bit too much duration" comment on the intake cam? Bill that was Mychailo's comments, that I cut and pasted.:)
I think it will be fine.:)

Harvey.;)

Harvey,
Thanks! Now to the interesting stuff...what do your simulations indicate regarding the use of the NA2 cams (versus the NA1, intake change only)?
-Bill (exhaust cams already at DeltaCams, intakes to follow....oops, is this thing on?....)

[oab_au]

Harvey,
Thanks! Now to the interesting stuff...what do your simulations indicate regarding the use of the NA2 cams (versus the NA1, intake change only)?
-Bill (exhaust cams already at DeltaCams, intakes to follow....oops, is this thing on?....)

Sorry for the delay Bill, got a new computer, could not get my 'one handed key board' to work, OK now.:)
I don't really know what you mean Bill. You can't compare the two cam set ups, as they are for two different applications.

The NA 1. is really for people that just want to fill out the top of the torque curve, instead of it dropping off after 5000. This is what the cam timing should have been, but for the non interference desires.

The NA 2. is to extend the rev range. It will increase the torque at higher rpms, and will accommodate moving the torque peak higher up the rev range.

The power output using these cams, will depend on the inlet/ exhaust tuned length that is used with them. If the maximum is required, these lengths will have to be shortened to suit the higher torque peak. If they are left as is, they will still produce a very strong torque flow, into the higher rpms.

You could fit the cams on their own, for starters. Then decide if you want to go the whole hog, and do the inlet/exhaust latter.

I'll do some more work on the simulation of the project, as time permits, and post it on a new thread.

Harvey.;)

[Trevor]

Well guys can we seriously come up with a couple agreeable stats then??

1. N/A mild grind for those looking for a little more
2. N/A aggressive grind for those looking to make a serious machine
3. FI turbo grind for those turbo builders
4. FI S/C grind for those purchasing LAN's Stage 3 or going with a homegrown S/C like svxfiles??

I mean, this should not be too much to ask and that is what this thread is really all about

Tom

Tom, are you still there? :confused:

I commiserate with you, as I am aware that in frustration you have lost interest in WHAT WAS YOUR thread. In desperation you pleaded for ungarnished specifics, only to be presented with the need to carry out more research. As a retired old bugger, :o I have time available and therefore assist with the following summation of the data rather thoughtlessly presented from the other quarter.


----------Stage 1. would be increasing the lift on the inlet cam, keeping the duration as close to the 240*.

Stage 2. Would use a longer 250* duration on both inlet and exhaust cams, with 8mm lift on both, and lobe centers set to suit the gearbox used, standard for an auto, 119*

Stage 2. Would use a longer 250* duration on both inlet and exhaust cams, with 8mm lift on both, and lobe centers set to suit the gearbox used, standard for an auto, 119*

The stage one turned out to be on the ball. The only change would be to use the standard SVX exhaust profile 244* at 8mm lift, instead of the Nissan one.

S14 KA24DE motor (late model 240SX)
intake profile: 0.350" lift, 206 deg @ 0.050" (a bit too much duration)
exhaust profile: 0.350" lift, 200 deg @ 0.050" (almost too much duration, but probably ok).

About 257* duration, 8 75mm lift on both inlet and exhaust. I have used these in a simulation, and found it to produce strong torque to 7000 rpm. This set would suit most road applications.
For the extremist like Dynomat, we need about 260* .at 9mm lift, on both inlet and exhaust. But this would need a lot of serious engine work to work well, and would be for racing mainly, running into the 8000 rpm mark.-------------


N.B. When recommendations are called for, reputation is on the line and as shown above, there is little risk in putting forward that which is unspecific, a well as conservative. I state emphatically that the above notably only broadly defined figures, no matter how correlated, will not provide real bang for bucks.

Those embarking on a modification, with fun as the main ingredient, require the work in hand to be both cost and labour effective. I am sure the figures suggested above will not provide the required degree of satisfaction.

The engine has been rated by many as bullet proof, but in any event, within this form of exercise a degree calculated risk is imperative. Within the context of what is being proposed here and N/A, an 8,000 RPM red line is not out of place using the standard internals. Unless the power band is lifted above 7,000 RPM the exercise is futile.

Pussy footing is for poofters, Trevor. ;)

[SilverSpear]

About 257* duration, 8 75mm lift on both inlet and exhaust. I have used these in a simulation, and found it to produce strong torque to 7000 rpm. This set would suit most road applications.
For the extremist like SilverSpear and Dynomat, we need about 260* .at 9mm lift, on both inlet and exhaust. But this would need a lot of serious engine work to work well, and would be for racing mainly, running into the 8000 rpm mark.---------



My first choice is N/A tuning for the EG33, any extreme figure and I am happy about it since I am going 6 speed and an entirely overhauled engine.

I have been digging around before war broke out, it seems that turning hydraulic lifters to solid ones is a speciality of mechanics and machining shops around here...

Trevor can you give more info about this setup you mentioned? Max HP at ???? etc...

[Trevor]

My first choice is N/A tuning for the EG33, any extreme figure and I am happy about it since I am going 6 speed and an entirely overhauled engine.

I have been digging around before war broke out, it seems that turning hydraulic lifters to solid ones is a speciality of mechanics and machining shops around here...

Trevor can you give more info about this setup you mentioned? Max HP at ???? etc...

Sorry if I have caused confusion in setting out the post. You have quoted data originating from Harvey, summarized from hither a thither. Please back track to post No. 69 for my recommendations. I do not go along with the lift specified by Harvey.

Suitable lobe design accepted, added lift requires an increase in parasitic power/torque. The implications in respect of increased mechanical loading are paramount in this application which involves multiple cam shafts, well separated and therefore driven by a very long belt. As a result there is excellent vibration damping, but the drive is somewhat deficient in other areas. Consider possible stretch, bounce, strength, tracking. A sophisticated tensioner/damper has been incorporated for very good reason.

Four large valves, provide a large controlled port area, but add to the mechanical loading. The tradition of increasing lift is based on increasing what was in the past defective port area, by way of accepting an increase in mechanical stresses. Raising RPM is a major factor against raising valve lift beyond mechanically viable levels.

Argument towards increasing lift must therefore be carefully evaluated.The OEM lifters should prove adequate, but if you have easy access to engineering facilities, take this into account.

I am confident that the many serious mechanical issues high lift involves and which call for extra modifications are obvious and do not require spelling out here. This could be regarded as a defining point which takes the project into another area of high tech/cost, rather outside the realms of amateur activity.

Doing mods progressively in logical stages makes sense from all points of view. Cost, time and satisfaction. Most important is that losses in one area, can be masked by an improvement in another and results misconstrued.

Any performance figure, quoted on the basis of what amounts to broad specifications can be no more than a guess and yours is as good as mine or anyone else's.

I intend this post to terminate my comments, as from here on in only argument can ensue. If observation is made that engine tuning is more art than science, this will not be far astray. Have Fun. :D

[SVXRide]

Sorry for the delay Bill, got a new computer, could not get my 'one handed key board' to work, OK now.:)
I don't really know what you mean Bill. You can't compare the two cam set ups, as they are for two different applications.

The NA 1. is really for people that just want to fill out the top of the torque curve, instead of it dropping off after 5000. This is what the cam timing should have been, but for the non interference desires.

The NA 2. is to extend the rev range. It will increase the torque at higher rpms, and will accommodate moving the torque peak higher up the rev range.

The power output using these cams, will depend on the inlet/ exhaust tuned length that is used with them. If the maximum is required, these lengths will have to be shortened to suit the higher torque peak. If they are left as is, they will still produce a very strong torque flow, into the higher rpms.

You could fit the cams on their own, for starters. Then decide if you want to go the whole hog, and do the inlet/exhaust latter.

I'll do some more work on the simulation of the project, as time permits, and post it on a new thread.

Harvey.;)

Harvey,
Sorry for any confusion caused by my post. Your comment above (now in bold)was what I was looking for. More specifically, I was wondering if your computer simulations - based on the use of the NA2 intake and exhaust cams - indicated any significant loss in idle/off idle performance (versus the NA1 configuration). Yes, I will be going the NA2 route as soon as I get a set of stock intake cams to ship off to Scott (he's already got a set of exhaust cams I sent out a while back..). The cams will be going in my "spare" engine that is currently sitting on an engine stand in my garage - right now I'm just planning on port-matching the intake manifold/injector stacks/heads/exhaust manifolds, with polishing only on the exhaust side. The intake runner length will be a little longer than stock, but only because I'll have the phenolic spacers installed - future "R&D" on runner length is a given :cool: .
-Bill

[TomsSVX]

Trevor, I am still here and I now know what I need to know. Thanks for your time and effort it has not fallen upon deaf ears

Tom

[oab_au]

Harvey,
Sorry for any confusion caused by my post. Your comment above (now in bold)was what I was looking for. More specifically, I was wondering if your computer simulations - based on the use of the NA2 intake and exhaust cams - indicated any significant loss in idle/off idle performance (versus the NA1 configuration). Yes, I will be going the NA2 route as soon as I get a set of stock intake cams to ship off to Scott (he's already got a set of exhaust cams I sent out a while back..). The cams will be going in my "spare" engine that is currently sitting on an engine stand in my garage - right now I'm just planning on port-matching the intake manifold/injector stacks/heads/exhaust manifolds, with polishing only on the exhaust side. The intake runner length will be a little longer than stock, but only because I'll have the phenolic spacers installed - future "R&D" on runner length is a given :cool: .
-Bill

OK Bill, if you want to have a go at this next cam set, we will get to work on it. We need to do some ground work with Scott at Delta, to verify the lobe specifications are what I think they are. We can continue this on the "Camshaft Lobes" thread as all the lobe info that Ron has found is there.

As for how much of the IRIS low speed torque will be lost? Matt asked me this, and this is what I said about it.

The Iris is two systems, the low speed inertia section does rely on the cam duration being the 240*, so that as one valve closes, the next opens. This allows the pressure to build up in the manifold for the next valve to open to the positive inertia pressure.

It also adds Inertia pressure to the end of the inlet phase, as the valve is closing.

As the duration is increased, the period of pressure build up, between inlet openings is decreased. This decreases the amount of inlet pressure at the start of the inlet phase. The Inertia pressure at the end of the inlet phase will still operate, just the opening pressure will be decreasing.

The NA 1. cam has no significant increase in duration, so the IRIS low speed torque is not affected. The extra lift enables the cylinder filling to continue up the range, instead of dropping off.

The NA 2. cams have about 21* more duration. This is needed to allow the engine to develop the torque at higher rpms. As with the standard inlet cams, there is 4*s between inlet openings( each side of the engine is separated at this time). With these NA 2. cams the inlet openings overlap by 21*, so there will be a loss of some of the IRIS inlet pressure as the valves are opening. This loss will be more noticeable with an auto running the high final drivel ratio. A manual can get around this loss, by using the stick to cover the loss.


Harvey.;)

[cdigerlando]

Any recommendations for FI cams? I really think the power band needs to be increased to 6500 rpm to see some real benifits.

[oab_au]

Any recommendations for FI cams? I really think the power band needs to be increased to 6500 rpm to see some real benifits.

Hi Mate, the Na 1. will be fine for both Turbo and Supercharges. This does increase the power at higher rpms. Check the reports from the members that are using this cam now, to see the effect it has on the higher rpms.

Harvey.;)

[SVXRide]

OK Bill, if you want to have a go at this next cam set, we will get to work on it. We need to do some ground work with Scott at Delta, to verify the lobe specifications are what I think they are. We can continue this on the "Camshaft Lobes" thread as all the lobe info that Ron has found is there.

As for how much of the IRIS low speed torque will be lost? Matt asked me this, and this is what I said about it.

The Iris is two systems, the low speed inertia section does rely on the cam duration being the 240*, so that as one valve closes, the next opens. This allows the pressure to build up in the manifold for the next valve to open to the positive inertia pressure.

It also adds Inertia pressure to the end of the inlet phase, as the valve is closing.

As the duration is increased, the period of pressure build up, between inlet openings is decreased. This decreases the amount of inlet pressure at the start of the inlet phase. The Inertia pressure at the end of the inlet phase will still operate, just the opening pressure will be decreasing.

The NA 1. cam has no significant increase in duration, so the IRIS low speed torque is not affected. The extra lift enables the cylinder filling to continue up the range, instead of dropping off.

The NA 2. cams have about 21* more duration. This is needed to allow the engine to develop the torque at higher rpms. As with the standard inlet cams, there is 4*s between inlet openings( each side of the engine is separated at this time). With these NA 2. cams the inlet openings overlap by 21*, so there will be a loss of some of the IRIS inlet pressure as the valves are opening. This loss will be more noticeable with an auto running the high final drivel ratio. A manual can get around this loss, by using the stick to cover the loss.


Harvey.;)

Harvey,
Yep, definitely ready to have a go at the NA2 cams, as they'll go in the engine currently sitting on a stand in my garage (which will also be getting some lighter internal parts;) - thanks Ron!).:cool: I'll look for you over in the "Camshaft Lobes" thread
-Bill

[longassname]

Hello boys and girls. Bill, SVXride, contacted me regarding the cams he's working on and I'm more than happy to help. I believe I can spec a profile that will work very well both for the na guys and for forced induction crowd.

Something I noticed that was left out of consideration thus far is the timing of the fuel injection. Because our ecu times fuel injection to end imediately before the opening of the intake valve it is necessary to be wary of long durations and fast acting profiles and especially the combination of the two. With too much overlap while the valve is significantly open you end up with too much of your fuel charge going straight through to your exhaust causing a lean mix in the combustion chamber along with sky rocketing egt's.

The image below specs a couple of profiles that will give big increases in flow without that problem. The 3rd option is a combination of profile 1 for the intake cams and profile 2 for the exhaust cams. If you only want to grind one option this one would be your biggest bang for the buck.
http://www.ecutune.com/posts/SVXCamProfile.gif

[longassname]

in fact you guys may want to look into if option 3 can be done without changing valve springs. It looks to be in the realm........

[longassname]

also, my base circle measurements are infered. It would probably be a good idea to verify them with actual measurements.

I emailed Matt with a request to assist a valve spring guy down under with getting all the information to run our valve train through his simulator to make sure the tensions are sufficient to maintain control of the valves at the rpms and airflows we'll be wanting. I believe option 3 will not have coil binding with the factory springs if they are strong enough to maintain control of the valves (you guys who are measuring this stuff may want to double check that) but the question remains of whether they will keep the valves under control with the airflows we'll see under various levels of boost.

[Nemesis Destiny]

This might've saved Trevor and Harvey a LOT of arguing back and forth... :rolleyes:

[SilverSpear]

This might've saved Trevor and Harvey a LOT of arguing back and forth... :rolleyes:

comments???

[cdigerlando]

in fact you guys may want to look into if option 3 can be done without changing valve springs. It looks to be in the realm........

Are cams something that you plan on testing and offering for sale? Also, are you located in Tampa? I thought you were in the Miami area.

[cdigerlando]

comments???

I would love to have a comment, but this is way over my head.

[oab_au]

comments???

Danny, I discuss, I don't argue. Something I learned a long time ago,

"Never argue with an idiot, they bring you down to there level, and beat you with experience":D

Harvey.;)

[Trevor]

Danny, I discuss, I don't argue. Something I learned a long time ago,

"Never argue with an idiot, they bring you down to there level, and beat you with experience":D

Harvey.;)

Unfortunately within this thread, I have had no other choice. :p

[SVXRide]

You know, one would almost think that Harvey and Trevor go way back and that they enjoy the verbal "sparing";) :D
-Bill

[SilverSpear]

You know, one would almost think that Harvey and Trevor go way back and that they enjoy the verbal "sparing";) :D
-Bill

Precisely!, all what I said is "Comments" and I caused a cold war between the veterans :D

[mikecg]

So we putting together a group buy soon or what?:cool:

[SVXRide]

So we putting together a group buy soon or what?:cool:


patience....patience....;) :cool:
-Bill

[oab_au]

Mike are you going to get profiles made? if so it does open the options. It is easy to come up with some figures, finding a cam that has the profile that we want is difficult.

The way I see it is that we have two options, one for Autos and one for manuals. The difference is the usable rev range. The Auto is held to having the maximum torque at 5000, due to the change points, and the limited maximum rev range. So there is no point in using a longer duration profile that will move the torque out of their usefully range. There going to do most of their running between 2000-4000, with a run to 6500 rarely. It is better to increase the torque across the rev range, that the 8mm lift has shown to do. Too much duration will rob them of usefully torque, and give some more power above 5000, that they will rarely use.

The same effects control how much lift we can use. 8mm loses a small amount of inlet gas velocity around 2000. 9mm looses it to 2500. I think the 8mm is about all the autos can use on the inlet. Increasing the lift on the exhaust, for this rev range offers no usefully increase.

The manuals are a different set of conditions. Lower overall gearing, and the number of gears, allows the rev range to open up. The driver can use the gears to keep the engine in the usefully range. With the rev limiter extended to 7500, there is the option to move the torque peak from 5000 to 6000. Longer duration and more lift is needed to allow the engine to maintain its cylinder filling at this speed. There will be a appreciably loss below 3000, but rowing the box can get around this.

The problem in moving the torque up to 6000 is the tuning of the inlet and exhaust tracts. I can assure you that the torque peak won't move unless the lengths are altered. The exhaust is easy, the inlet is not so easy. It would take somebody like yourself:) , that has the capacity to do some surgery on the inlet manifold, to shorten the two dividers between the runners to reduce their length, to move the torque peak up. With the Inlet tract shortened to suit the higher engine speed, the 257* at 9mm on both cams would allow peak horsepower to 7000.

Maybe some body;) could offer an exchange service in modified manifolds.:)

Harvey.;)

[longassname]

Harvey, I understand the cam you are suggesting to be used on a naturally aspirated, automatic svx. You have two goals in mind:
1) you want to take the best advantage you can of the existing negative pressure waves to accelerate the intake charge into the cyllinder
2) you want to minimize the reduction in intake velocity at lower rpms that happens as an effect of the changes made to slow the drop in torque above it's peak.

Those are good goals to use in the design of a cam for an otherwise stock svx. No arguements here at all. I aggree with your reasoning behind choosing those goals too. If you can't run higher rpms and you don't drive on the upperside of the rpm band then why would you give up the part of the torque curve you actually use for high rpm performance. I give my nod to your assertions on the design of a mild cam for a stock svx.

[oab_au]

I don't think we can do any better, than use the std exhaust profile for the inlet cam. It has, the same fast opening profile as the original inlet, with only 4* more duration, while gaining 13% more lift.

The profile that we used for the first set, was a slow opening cam. It had a seat to seat duration of 247*? as against the 240* of the exhaust profile, but both have the same 194* duration at 0.050" lift. The extra 11 degrees taken up by the slow opening, just lost more of the Iris torque and, the fast start to the inlet sonic wave.

This will keep the better part of the low speed Inertia system torque, ensure a good start to the inlet sonic wave, while the 8mm lift will allow the torque to continue further up the rev range.

The extra breathing will increase the maximum torque slightly, but it will broaden the torque curve, so the engine will run harder at the top end. Driving this cam setup in third gear, will certainly put a smile on the face.

Whats more, this profile is available.:)

Harvey.;)

[Trevor]

So my initial thoughts about using our exhaust profiles may have been dead on. I was thinking of just using the same profile as the exhaust on the intakes. Leaving us with exactly what you are recommending. I will call Scott this week at Delta and make sure he still has the exhaust profile fom the cams Bill sent him. I will also see what kind of price we are looking at as it seemed every time I called, the price went up

Tom

A reply to my post, from way back and dated 05/15/2006.

Decisions :confused: :)

[SVXRide]

Scott has a full set of EG33 intake and exhaust cams...trust me on this;)
He also has some other "interesting" cores I just sent him...
patience....patience:)
-Bill

[NeedForSpeed]

Happy Thanksgiving to all!!

Bill, what was the bucket diameter on those heads?

Scott has a full set of EG33 intake and exhaust cams...trust me on this;)
He also has some other "interesting" cores I just sent him...
patience....patience:)
-Bill

[NeedForSpeed]

The major cost is modded cams is welding. I believe the exhaust lobe can be successful without welding, only reducing the base circle. Potentially, a low-budget option, perhaps the best bang for the buck of any mod?

Now, let's Zee those "interesting" specs.

[oab_au]

The major cost is modded cams is welding. I believe the exhaust lobe can be successful without welding, only reducing the base circle. Potentially, a low-budget option, perhaps the best bang for the buck of any mod?

Now, let's Zee those "interesting" specs.

Yes Ron, we can get the same specs as the welded ones, by grinding the lobe profile smaller, so that the base circle is 1mm smaller, and just rely on the lifters to take up the extra gap. But we still need a profile for the cam grinder to use.:) We either need an existing cam with that profile, or we need to make a profile that they can use.

Harvey.;)

[longassname]

Well good luck with your cams for otherwise stock svx's. They don't pertain to my area of interest so don't take my ignoring any discussion about that line of cams the wrong way. I'm just only interested in the higher performance svx'ing and will be continuing along the lines of the specs I mentioned earlier. I'll throw in a little advice though before signing off of the mild cam discussion. The intake valves are shorter than the exhaust valves but the springs are the same for both. If you make the exhaust lift in the neighborhood of .7 or .8mm more than the intake your spring tensions will be more equal and you will get a smoother running valvetrain. Also on the discussion of lift I would be very suprised if you didn't continue to get enough benefit from increasing lift on up to 30% of valve diameter to make it worth while.

A few of you now have gotten the svx cams measured by camshops; could someone please verify the actual base circle measurements please?

[NeedForSpeed]

Mike, I have more than one project, so I'm interested in mild low-budget cams for otherwise stock svx's, as well as the higher performance options you are profiling. I'm not ignoring either discussion, I'm interested in your persuit of performance. I believe someone posted the base circle in one of the threads, did you search it?

The profiles you mentioned, for high perf NA, or for the next Stage 3?

Harvey, the major cam grinders do have the exhaust lobes copied or cams to copy, so no worries there. Reduced base-circle exhaust lobe intakes should cost less than $100 per cam. Could be one of the best 'bang for the buck' available. That, plus program changes, should be huge for otherwise stock svx.

Well good luck with your cams for otherwise stock svx's. They don't pertain to my area of interest so don't take my ignoring any discussion about that line of cams the wrong way. I'm just only interested in the higher performance svx'ing and will be continuing along the lines of the specs I mentioned earlier. I'll throw in a little advice though before signing off of the mild cam discussion. The intake valves are shorter than the exhaust valves but the springs are the same for both. If you make the exhaust lift in the neighborhood of .7 or .8mm more than the intake your spring tensions will be more equal and you will get a smoother running valvetrain. Also on the discussion of lift I would be very suprised if you didn't continue to get enough benefit from increasing lift on up to 30% of valve diameter to make it worth while.

A few of you now have gotten the svx cams measured by camshops; could someone please verify the actual base circle measurements please?

[oab_au]

Mike this 240* 8mm lift inlet cam, is not just for stock engines. It is for engines that are going to operate in the < 7000 rpm range. This includes the blown engines, Positive Displacement, Centrifugal, or Turbo. They operate in this rev range, and will benefit from the extra lift, to allow the cylinder filling to continue higher up the rev range, instead of dropping off as the 7mm lift engines do.

Engines that are to operate in the >7000 range, need the inlet tract length reduced to raise the torque peak to 6000 rpm. Regardless of the cam timing/duration used, the torque peak will still follow the resonate peak. The inlet tract reduction, is it the order of 3"/75mm.

This is a basic simulation of the engine using a seat to seat duration of 257* 8.75mm lift fast opening cam, on both inlet and exhaust. The first has the standard length inlet and exhaust tract lengths.

RPM KW NM
3000 93.84 298.68
4000 142.32 339.78
5000 193.92 370.38
6000 213.72 340.14
7000 212.46 289.8
8000 203.76 243.18

When the inlet and exhaust tracts are shortened to suit the higher torque rpms, it looks like this.

RPM KW NM
3000 90.36 287.7
4000 132.18 315.48
5000 186.54 356.22
6000 221.22 352.08
7000 239.46 326.7
8000 224.34 265.8

Having the tract changed to move the torque up the rev range, moves the power up another 34 HP, at 7000. with the same cam shafts.

Harvey. ;)

[longassname]

The camshafts you speced are not big enough for the blown engines, sure they are better than completely stock but they aren't the best. Like I said before I would be suprised if increases in lift on up to 30% of valve diameter decreased the speed of low/mid rpm airflow enough to have a big enough impact to make it not worth the extension of torque past peak on a stock car; on a blown engine there is no question that further increases in lift would be worth it. We need a longer duration as well. We need to start the exhaust flow out of the cyllinder earlier.

I Know you have grabbed onto resonate frequencies with both hands but you have to remember that you can only take advantage of the resonate effects after you have dealt with the gas effects. The 256 cams are well proven on wrx's, z's and both na(jdm) and turbo supras. They allow the aiflows we are looking for with lots of streetable power accross the entire power band.

[Trevor]

The camshafts you speced are not big enough for the blown engines, sure they are better than completely stock but they aren't the best. Like I said before I would be suprised if increases in lift on up to 30% of valve diameter decreased the speed of low/mid rpm airflow enough to have a big enough impact to make it not worth the extension of torque past peak on a stock car; on a blown engine there is no question that further increases in lift would be worth it. We need a longer duration as well. We need to start the exhaust flow out of the cyllinder earlier.

I Know you have grabbed onto resonate frequencies with both hands but you have to remember that you can only take advantage of the resonate effects after you have dealt with the gas effects. The 256 cams are well proven on wrx's, z's and both na(jdm) and turbo supras. They allow the aiflows we are looking for with lots of streetable power accross the entire power band.

Michael, I agree whole heartedly.

As I have said before and now say again, the figures suggested throughout, have not been aggressive enough and will not provide bangs for bucks. In this respect the safe option IS the safe option for anyone recommending when they are not spending on the project.

[oab_au]

The camshafts you speced are not big enough for the blown engines, sure they are better than completely stock but they aren't the best. Like I said before I would be suprised if increases in lift on up to 30% of valve diameter decreased the speed of low/mid rpm airflow enough to have a big enough impact to make it not worth the extension of torque past peak on a stock car; on a blown engine there is no question that further increases in lift would be worth it. We need a longer duration as well. We need to start the exhaust flow out of the cyllinder earlier.

I Know you have grabbed onto resonate frequencies with both hands but you have to remember that you can only take advantage of the resonate effects after you have dealt with the gas effects. The 256 cams are well proven on wrx's, z's and both na(jdm) and turbo supras. They allow the aiflows we are looking for with lots of streetable power accross the entire power band.

Mike the objective of any modifications is to improve the performance of the car, not just the engine. What ever engine type you build, it has to go in a car and do the normal duties. A PD blower on a road car may spend probably no more than 10% of its running time on boost. The rest of the time it has to drive smoothly, and economical.

Now I don't know what type of engine your objectives are, but you need to define them. What speed do you want the engine to operate at. Less than 7000 rpm, or above, up to 8500/9000? Is it a 100% race engine, or a road engine?

There is no point in using a long duration cam, if it is not going to rev above 7000. A short duration cam, that has very large lift (30% of valve dia.), will need very strong valve springs to handle the very fast acceleration rates, that the lift will produce.

The main point in fitting a Positive Displacement blower is that it increases the air pressure that the engine operates under, across the entire rev range. This means that you don't have to increase the revs that the torque is made at, to increase the HP. The engine can be relative standard, and still produce the HP, from 2000 up.:)

To increase the rev range that the engine will operate at, you still have to do the same breathing mods as an N/A engine. Longer duration, more lift and larger valves. It will still have the same low speed problems as the N/A engines have. Fitting a PD blower won't negate these effects.

So what do you want, it to be?:)

Harvey.;)

[Trevor]

Mike the objective of any modifications is to improve the performance of the car, not just the engine. What ever engine type you build, it has to go in a car and do the normal duties. A PD blower on a road car may spend probably no more than 10% of its running time on boost. The rest of the time it has to drive smoothly, and economical.

Now I don't know what type of engine your objectives are, but you need to define them. What speed do you want the engine to operate at. Less than 7000 rpm, or above, up to 8500/9000? Is it a 100% race engine, or a road engine?

There is no point in using a long duration cam, if it is not going to rev above 7000. A short duration cam, that has very large lift (30% of valve dia.), will need very strong valve springs to handle the very fast acceleration rates, that the lift will produce.

The main point in fitting a Positive Displacement blower is that it increases the air pressure that the engine operates under, across the entire rev range. This means that you don't have to increase the revs that the torque is made at, to increase the HP. The engine can be relative standard, and still produce the HP, from 2000 up.:)

To increase the rev range that the engine will operate at, you still have to do the same breathing mods as an N/A engine. Longer duration, more lift and larger valves. It will still have the same low speed problems as the N/A engines have. Fitting a PD blower won't negate these effects.

So what do you want, it to be?:)

Harvey.;)

Mike has posted information which absolutely confirms his knowledge of the subject. He has a right to feel insulted as a result of a prolonged, arrogant lecture, from a proclaimed know all, instructing him how to suck eggs.

It is stated. ---- "To increase the rev range that the engine will operate at, you still HAVE to do the same breathing mods as an N/A engine."

Forced induction will increase breathing throughout the rev range regardless, and most certainly improves cylinder filling at the top of the rev range. In respect of an engine driven blower, the key in this respect is gearing.

[longassname]

Harvey,

The 256 total duration cam is an excellent cam for below 7000 rpms. The powerband of the lobes I offered up the specs on is a nice, wide, streetable powerband.

Comparatively the cams you are specifying do not have the lift or duration necessary for efficient evacuation of the ehaust on the blown cars even at moderate rpms. In fact I will probably go with a 264 duration exhaust cam.

[longassname]

Harvey,

You are right that the duration constraints you are placing on the cams you are spec'ing limit the increases you can make in lift without replacing the valve springs. If you want to increase the lift on the mild cams you are spec'ing for the stock guys they can use the same springs I'll be using with my cams. I can supply them for $300 a set.

[mikecg]

Harvey,

You are right that the duration constraints you are placing on the cams you are spec'ing limit the increases you can make in lift without replacing the valve springs. If you want to increase the lift on the mild cams you are spec'ing for the stock guys they can use the same springs I'll be using with my cams. I can supply them for $300 a set.


What....... Your going to sell cams for the Stage III people....... $300!!!!......I'm in. You want my car for testing??? I've got a vaction to Orlando coming up end of January.

[NeedForSpeed]

That's not how I read it!

What....... Your going to sell cams for the Stage III people....... $300!!!!......I'm in. You want my car for testing??? I've got a vaction to Orlando coming up end of January.

[mikecg]

That's not how I read it!


Ooops, I just reread that. He's offering springs....... My bad.

[sicksubie]

300.- per cam?

[longassname]

springs springs springs..not cams...24 sets of double springs with higher tension and plenty of lift before coil bind.

I think bill is arranging ordering cams for other people but I don't know the specs of the cams he's settled on if he has.

[SVXRide]

springs springs springs..not cams...24 sets of double springs with higher tension and plenty of lift before coil bind.

I think bill is arranging ordering cams for other people but I don't know the specs of the cams he's settled on if he has.


In work......in work....;) :cool:
-Bill


Michael,
Given a fixed valve stem length, are you going to a smaller diameter wire in order to support more lift before coil bind?
-Bill

[sicksubie]

I know that. I didn't mean per cam as in 300.- for the camshaft. I meant 300.- per set of springs per cam.

[sicksubie]

And in which case you will be hearing from me over the winter for the springs and the new version of the stage 2

[longassname]

24 sets of springs (I say sets because they are double springs--2 springs per valve) does an entire engine.

Bill, if you want I can send you a pair of valve springs to install into your head and have your machinist measure installed coil bind. Just don't take a long time to get it back to me and leave me waiting to set up my heads.

[sicksubie]

Are you going to delve into having cams available to go with the springs?

[mikecg]

24 sets of springs (I say sets because they are double springs--2 springs per valve) does an entire engine.

Bill, if you want I can send you a pair of valve springs to install into your head and have your machinist measure installed coil bind. Just don't take a long time to get it back to me and leave me waiting to set up my heads.

Put me down for a order of springs.

[longassname]

There is no way I could stock cams and there is no way I can get cams made for less than the price these guys are getting at delta. The price they are getting is below the price a shop gets charged for batches of 5 sets of cams at places like web. If bill wants me to help him get the cams I am spec'ing made I'll do that. If not, you can order your cams the same time I order mine if you want my specs. You'll need to get your money ready if it's not already. I don't have to search for profiles I can settle for. I can pull the trigger on this anytime and I'll be doing so very soon.



Are you going to delve into having cams available to go with the springs?

[mikecg]

Edit .......never mind

[sicksubie]

How much for your cams if we order together? Also not to sound lazy but what exactly are the specs on the cams that you proposed without going back over the previous 16 pages? Will they be good for a SVX that will be N/A for a while yet? I will be getting a good chunk of money on monday or tuesday. So, let me know.

[SVXRide]

24 sets of springs (I say sets because they are double springs--2 springs per valve) does an entire engine.

Bill, if you want I can send you a pair of valve springs to install into your head and have your machinist measure installed coil bind. Just don't take a long time to get it back to me and leave me waiting to set up my heads.


Michael,
thanks for the offer. If things work out right this week, I should have my cams by Christmas. How does early January work with your plans? I'd have the springs back to you within a week of receiving them (figure it will take at least a day or two to get from MD to FL)
-Bill

[longassname]

Why do you need your cams to check the lift at coil bind? I'll be installing my cams in december as well and will need the complete set at the time. I can send them to you this week if you can take your measurements this weekend or early next week.


Michael,
thanks for the offer. If things work out right this week, I should have my cams by Christmas. How does early January work with your plans? I'd have the springs back to you within a week of receiving them (figure it will take at least a day or two to get from MD to FL)
-Bill

[sicksubie]

There is no way I could stock cams and there is no way I can get cams made for less than the price these guys are getting at delta. The price they are getting is below the price a shop gets charged for batches of 5 sets of cams at places like web. If bill wants me to help him get the cams I am spec'ing made I'll do that. If not, you can order your cams the same time I order mine if you want my specs. You'll need to get your money ready if it's not already. I don't have to search for profiles I can settle for. I can pull the trigger on this anytime and I'll be doing so very soon.
Money is waiting...

[longassname]

Put it away somewhere safe (from you) and keep it till new years and then you can buy camshafts and springs as a late christmas present from you to you.

I'm going to make a set for myself and install and test them right after I finish dyno'ing stage1v5 and stage2v7. I'm planning on a dyno session for stage 1v5, a dyno session for stage2v7, and a dyno session for stage2v7 with cams.

Money is waiting...

[NeedForSpeed]

that sounds like Christmas fun for all of us!

Put it away somewhere safe (from you) and keep it till new years and then you can buy camshafts and springs as a late christmas present from you to you.

I'm going to make a set for myself and install and test them right after I finish dyno'ing stage1v5 and stage2v7. I'm planning on a dyno session for stage 1v5, a dyno session for stage2v7, and a dyno session for stage2v7 with cams.

[sicksubie]

Put it away somewhere safe (from you) and keep it till new years and then you can buy camshafts and springs as a late christmas present from you to you.

I'm going to make a set for myself and install and test them right after I finish dyno'ing stage1v5 and stage2v7. I'm planning on a dyno session for stage 1v5, a dyno session for stage2v7, and a dyno session for stage2v7 with cams.
Let me know when they are ready. I will get the stage 2v7 and the springs, and get cams. Dyno plots would be great as well. Also, what are the prices we are looking at for the cams and will you be testing just intake or both intake and exhaust?

[SVXRide]

Why do you need your cams to check the lift at coil bind? I'll be installing my cams in december as well and will need the complete set at the time. I can send them to you this week if you can take your measurements this weekend or early next week.

Ah, because I was tired and wasn't thinking?:rolleyes:
Go ahead and send them this week and I'll have them back to you ASAP, as I've still got my spare heads sitting at my machinist's shop.
-Bill

[longassname]

Ok, if you could paypal me some change (litterally change, i think you can papal even just a few cents) and mark it as a payment for an item it will give me a link to use to ship to you.

Ah, because I was tired and wasn't thinking?:rolleyes:
Go ahead and send them this week and I'll have them back to you ASAP, as I've still got my spare heads sitting at my machinist's shop.
-Bill

[longassname]

I will be testing both intake and exhaust. I won't know any better how much it will cost to make a batch till untill after I have tested mine and we are ready to make a batch.

Let me know when they are ready. I will get the stage 2v7 and the springs, and get cams. Dyno plots would be great as well. Also, what are the prices we are looking at for the cams and will you be testing just intake or both intake and exhaust?

[SVXRide]

Ok, if you could paypal me some change (litterally change, i think you can papal even just a few cents) and mark it as a payment for an item it will give me a link to use to ship to you.


Michael,
You should have my shipping address from my Stage 1 and Stage 2 purchases.
-Bill

[longassname]

I just like to use the links they give me so it charges my paypal for the shipping and is easy. I suppose i can search out your address, figure out my usps login info, and enter in new shipping info.

Michael,
You should have my shipping address from my Stage 1 and Stage 2 purchases.
-Bill

[SVXRide]

I just like to use the links they give me so it charges my paypal for the shipping and is easy. I suppose i can search out your address, figure out my usps login info, and enter in new shipping info.

Michael,
Didn't think it would be so involved - I'll paypal you some coin this week.
-Bill

[longassname]

Bill,

I refunded your dollar and sent you a bill for a quarter. You marked it as payment for a service or shipping or something; like I said, it has to be marked as for goods for it to give me the link.

Anyway, I took pictures of the springs as I was boxing them up thinking I was going to ship them to Bill this morning. I know everyone likes pictures.

http://www.ecutune.com/posts/DSC_3771.jpg
http://www.ecutune.com/posts/DSC_3779.jpg

[SVXRide]

Michael,
Sorry, guess I missed the "goods" part....I'll fix things momentarily...
-Bill

[oab_au]

Mike, what are the specs of the springs. Load at height?, Coil bound height?

And do they come in any other colours.?:)

Harvey. ;)