Camshafts for the EG33.

[oab_au]

This topic came up in the High Compression thread, so to keep them apart we can talk about it here.

Bazza

That's right mate, standard cams at this point in time. They turn rather asthmatic around 550-600 bhp which from what I recalling Ecutune Mike saying it's mainly the exhaust cam.

Bazza

Does anyone have any testing behind this with the EG33 NA motor and the results before and after dialing in the cams? Reason I ask is I don't think it makes any difference on our motors and if anything actually gains top end.

Reason why is I've done a fair bit successful AVCS tuning on the intake cam (02-07 STI heads). As most know it effectively advances the intake cam during low end RPM and you wind it back to zero as revs and air flow climbs.

The result is a massive improvement in low end torque. 0 advance gives the best top end (no bottom end) so theoretically a couple more degrees of retard will help with more top end. Also the exhaust AVCS works by retarding the cam as the rpm and airflow climb - retarding makes more top end power.

So in english, decking the head in an EG33 and the resulting timing belt effects which cause overall retardation of all cams should if anything make the car more powerful up top due.

Yes mate I have done a bit on retarding the inlet timing, and yes it does affect the rpm that the torque is produced.
This was on a Nissan 3lt, moving the inlet 20*.



As you can see it picked up some top end torque, but the loss at the bottom end cost in the "off the start" acceleration.

When you are working out what type of cam timing to use, you have to look at where you need the torque to be in the rpm range that you are going to use. If you are using the standard inlet manifold, and still running the higher diff ratio, you need the torque that it provides between 2200 and 4000, then the 240* timing has to be the same to allow the Inertia system to work. The only change that will benefit is more lift. Both cams can go to 8.75mm, the inlets giving the best increase.

If it is to be a high rpm engine, with the torque from 4000 to 6000, or higher, running a low diff ratio, then you will have to do away with the low end torque from the Inertia system, and just tune to work in the higher rpms. To do this, either the standard inlet runners will have to be shortened, or 6 tuned length throttle bodies will be needed, to allow. The inlet resonance to suite the higher torque peak.

There are two cam functions that control the engines breathing. Valve lift will allow more air to enter the cylinder at all engine speeds, great for higher engine speeds, but will degrade the inlet velocity, that will hurt combustion at lower engine rpms. If there is less turbulence in the chamber then all the mixture will not burn and power will drop.

The other function is Duration, which is really the end result, of setting the valve timing points that the engine needs, to allow the torque to peak to arrive at the higher rpm. The air does not accelerate as fast as the piston, lagging behind as the rpm rises, and the inlet valve has to close when the cylinder pressure is at the highest.
At the 4800 rpm that the torque is at now, the inlet valve closes at 54* After Bottom Dead Center. As the engine speed rises the maximum cylinder pressure arrives letter when the piston is further up the cylinder. So we have to close the inlet valve about 10* latter to trap the highest pressure in the cylinder.

The exhaust valve timing, besides allowing the cylinder pressure time to drop, has to start the pressure wave that will start the inlet flow. Advancing the exhaust opening point from the 55* Before Bottom Dead Center, to about 65* BBDC to drop the pressure.

Adding boost from a supercharger will not change things greatly. A bit more exhaust opening advance may be needed, depending on how much boost is used. A Turbo does loose the exhaust action to start the inlet flow, as there is no resonance wave to help. This engine needs the inlet valve opened earlier to keep up with the engine speed, but if too much overlap is used, the exhaust gas pressure can interfere with the inlet phase.

Harvey.

[bazza]

Sorry Harvey, completely missed this thread.

Originally Posted by oab_au

Yes mate I have done a bit on retarding the inlet timing, and yes it does affect the rpm that the torque is produced.
This was on a Nissan 3lt, moving the inlet 20*.

Nice. That's exactly what I'd expect with 20 degrees change and is consistent with what I saw. With the AVCS engines I was playing with, I was advancing and retarding up to 45 degrees with massive changes in bottom end response and power. One of the very handy things was being able to "un-restrict" the engine while boosting to remove compressor surge. Basically a situation where the engine is not able to flow the air the compressor is supplying and starts stalling the blade and pushing back out past the blades. Basically you'd open the engine up (retard the cam back to 0) and the surge would go away.

As you can see it picked up some top end torque, but the loss at the bottom end cost in the "off the start" acceleration.

When you are working out what type of cam timing to use, you have to look at where you need the torque to be in the rpm range that you are going to use. If you are using the standard inlet manifold, and still running the higher diff ratio, you need the torque that it provides between 2200 and 4000, then the 240* timing has to be the same to allow the Inertia system to work. The only change that will benefit is more lift. Both cams can go to 8.75mm, the inlets giving the best increase.

If it is to be a high rpm engine, with the torque from 4000 to 6000, or higher, running a low diff ratio, then you will have to do away with the low end torque from the Inertia system, and just tune to work in the higher rpms. To do this, either the standard inlet runners will have to be shortened, or 6 tuned length throttle bodies will be needed, to allow. The inlet resonance to suite the higher torque peak.

There are two cam functions that control the engines breathing. Valve lift will allow more air to enter the cylinder at all engine speeds, great for higher engine speeds, but will degrade the inlet velocity, that will hurt combustion at lower engine rpms. If there is less turbulence in the chamber then all the mixture will not burn and power will drop.

The other function is Duration, which is really the end result, of setting the valve timing points that the engine needs, to allow the torque to peak to arrive at the higher rpm. The air does not accelerate as fast as the piston, lagging behind as the rpm rises, and the inlet valve has to close when the cylinder pressure is at the highest.
At the 4800 rpm that the torque is at now, the inlet valve closes at 54* After Bottom Dead Center. As the engine speed rises the maximum cylinder pressure arrives letter when the piston is further up the cylinder. So we have to close the inlet valve about 10* latter to trap the highest pressure in the cylinder.

The exhaust valve timing, besides allowing the cylinder pressure time to drop, has to start the pressure wave that will start the inlet flow. Advancing the exhaust opening point from the 55* Before Bottom Dead Center, to about 65* BBDC to drop the pressure.

Adding boost from a supercharger will not change things greatly. A bit more exhaust opening advance may be needed, depending on how much boost is used. A Turbo does loose the exhaust action to start the inlet flow, as there is no resonance wave to help. This engine needs the inlet valve opened earlier to keep up with the engine speed, but if too much overlap is used, the exhaust gas pressure can interfere with the inlet phase.

Harvey.

This is some pretty awesome information.

With turbocharging things change a little. You obviously force the air into the piston and when that valve opens you've got X psi of air forcing itself into a vaccum. So the issue with the air not accelerating as the piston moves down is very much reduced. You then have the exhaust gas powering the turbo, then you have turbulent airflow past the intercooler so you prolly tend not to see the fuel mix issues you would with an NA motor.

One major concern I have with the stock cams is that due to running hydraulic buckets and the associated ramp effects, the known durations of 230-240 (or whatever they are, sorry cannot recall off top of head) they really become more like 200-220 degrees or thereabouts if I'm not mistaken. Most likely why during testing as boost was increased peak power kept moving to the left which is very consistent with the other results showing the cams out of puff. Of course this is not fact and I also wonder if the valve seat pressure and or bounce possible contributed - however then again the RPM was very low - only 5500 rpm etc.

Also one other thing is the resonance system. Once on boost I don't think it makes any difference - the exhaust gas is powering the compressor and the compressor is forcing the engine to do some work etc etc. However from testing I've noticed under 0 psi (vacuum) and coming up onto full boost it does make a huge difference to the response and feel. Very hard to produce good data though and since the engine is boosting, quite tricky to figure out how to control the vacuum driven iris, hmmm. Could put a wastegate actuator there instead I guess?!

Anyway a friend of mine is in the process of flowing his EG33 heads, measuring everything and getting some cams made up. The cam shop has requested the current cam configuration and cams so they can measure the stock setup and go from there. Our plan is to use solid buckets and later model valves (most likely supertech). I'd be very keen to hear any advice you have regarding this. I am thinking of following something along the lines of 256 duration with 9.5 mm lift, aiming for peak power at 7000 rpm.

[Dessertrunner]

bazza
Matt had Mark in Canberra (you may know him) flow bench the heads and I paid Mark to do some measuring of the intact manifold.
Tony

[bazza]

Originally Posted by Dessertrunner

bazza
Matt had Mark in Canberra (you may know him) flow bench the heads and I paid Mark to do some measuring of the intact manifold.
Tony

Yeah I mentioned that to my mate but he kinda wants to check em again and he can do them for nothing so hard to argue.

[oab_au]

Originally Posted by bazza

Sorry Harvey, completely missed this thread.



Nice. That's exactly what I'd expect with 20 degrees change and is consistent with what I saw. With the AVCS engines I was playing with, I was advancing and retarding up to 45 degrees with massive changes in bottom end response and power. One of the very handy things was being able to "un-restrict" the engine while boosting to remove compressor surge. Basically a situation where the engine is not able to flow the air the compressor is supplying and starts stalling the blade and pushing back out past the blades. Basically you'd open the engine up (retard the cam back to 0) and the surge would go away.

Yes you are just moving the inlet closing point to a different rpm range, and the torque moves to there.

This is some pretty awesome information.

With turbocharging things change a little. You obviously force the air into the piston and when that valve opens you've got X psi of air forcing itself into a vaccum. So the issue with the air not accelerating as the piston moves down is very much reduced. You then have the exhaust gas powering the turbo, then you have turbulent airflow past the intercooler so you prolly tend not to see the fuel mix issues you would with an NA motor.

No they don’t change that way Bazza. As it is the air is forced into the cylinder when the valve opens, you have 14.7psi of air pressure forcing in to the vacuum. In your case the air pressure/volume is higher, and the weight of the air is heavier, but the time to get the air into the cylinder is the same. So the same conditions exist. The larger weight of air takes just as long to accelerate down the inlet track.
Yes the turbo certainly produces a lot of turbulence, but it’s the actual jet stream of gas entering the cylinder, through the valve that that produces the swirl that assists combustion, so it still has to be addressed.

One major concern I have with the stock cams is that due to running hydraulic buckets and the associated ramp effects, the known durations of 230-240 (or whatever they are, sorry cannot recall off top of head) they really become more like 200-220 degrees or thereabouts if I'm not mistaken. Most likely why during testing as boost was increased peak power kept moving to the left which is very consistent with the other results showing the cams out of puff. Of course this is not fact and I also wonder if the valve seat pressure and or bounce possible contributed - however then again the RPM was very low - only 5500 rpm etc.

The standard cam is 236* X 7mm inlet, 240* X 8mm exhaust. As the car with the high diff ratio spends most of the driving time between 2000 and 4000 rpm, these are a compromise to the low speed end of the torque curve. The butterfly valve closes at 2200rpm to form two separate systems. The low speed Inertia system has to have a duration of no more than 240*, as it relies on three cylinders, inducting one after another, every 240* to power a Helmholtz chamber, to develop a Intake pressure of about 7psi at 3200 rpm, and produces 95% of the peak torque at that speed. So you can see the reason for the low lift of 7mm to have a clean burning chamber at these low rpms.

At 4000 the valve opens and the whole inlet forms a plenum for the inlet tracts to resonate at 4800rpm and the peak torque is developed. This resonate system will still work the same with the higher air pressure. The inlet sound waves will operate to lower the cylinder pressure just the same.
A previous supercharger build, disregarded the system, and then didn’t produce the power that he expected, due to building a Inlet manifold that removed both systems, so instead of adding boost to a 240hp engine, the engine reduced to about 160 hp before the boost was added.

I guess that you don’t have the IRIS operating, so your torque would start at 4000. It would be worth setting it to turn on at 2200 and off at 4000, just to see the difference that it gives. Member Tapani has a turbo with the IRIS system working and he has more torque at the lower end than he can use. You may find that with the IRIS working and more lift plus the boost, you may not have to go to higher rpms to get the drive.

So in your case it depends on what engine rpm you use, what is the lowest that you use to pull out of a slow corner, what is the max rpm that you use for power? It is this range that you have to develop the engine for. If you are above 4000 all the time then the cam timing has to suit the rpm. The lift can be as big as you can accommodate. You can get 8.75mm before spring bind, after that solid lifters can get to 10/11. As a by the EZ30R has a top lift of 10mm with the inlet valve closing at 70* ABDC.

Also one other thing is the resonance system. Once on boost I don't think it makes any difference - the exhaust gas is powering the compressor and the compressor is forcing the engine to do some work etc etc. However from testing I've noticed under 0 psi (vacuum) and coming up onto full boost it does make a huge difference to the response and feel. Very hard to produce good data though and since the engine is boosting, quite tricky to figure out how to control the vacuum driven iris, hmmm. Could put a wastegate actuator there instead I guess?!

The valve has a vacuum tank that powers the valve under boost.

Anyway a friend of mine is in the process of flowing his EG33 heads, measuring everything and getting some cams made up. The cam shop has requested the current cam configuration and cams so they can measure the stock setup and go from there. Our plan is to use solid buckets and later model valves (most likely supertech). I'd be very keen to hear any advice you have regarding this. I am thinking of following something along the lines of 256 duration with 9.5 mm lift, aiming for peak power at 7000 rpm.

OK you come up with what the objectives of the engine are, and we can work to achieve it.

Harvey.

[bazza]

That's some good info thanks mate. You are correct in assuming IRIS valve not operational.

As for peak torque, yes close to 4000 rpm although turbo engines tend to always make peak torque around the same RPM peak boost is achieved earliest. I've attached the dyno plots to show what's going on. At low boost, 10 psi and below the engine is able to rev nicely, probably to 6000 rpm as you can see. Anymore boost and it hits a brick wall as you can see. At 3750 rpm it's making 710Nm of torque and you can see in the video below what the car does when WOT is applied at this rpm (1:05) ... tries to kill me haha. (Ingore the squiggles as it comes up to full power as it was wheel spinning on the dyno and confusing the dynomachine).





With this vacuum tank - anyone got a picture of this little device?

Harvey, this is how it's driven on the track, you can see the RPM's I use. http://www.youtube.com/watch?v=qssbthwIb4s

My desired RPM range will be from 5000-7000 rpm. Aiming for a very flat torque curve and an increasing power curve... similar to Porsche GT3's:

[dynomatt]

Just wanting to subscribe to this thread.

Harvey we've discussed this before. FWIW, if was building another engine I'd be considering more lift (like closer to 12mm), more duration (closer to 275 or 300 seat to seat), bigger valves, higher compression (12 or 13:1)etc.

And adjustable wheels so static timing can be perfect.

I think the combination of those would be a pretty handy racing application...not a torquey luxo barge setting.

Matt

[oab_au]

Originally Posted by bazza

That's some good info thanks mate. You are correct in assuming IRIS valve not operational.

As for peak torque, yes close to 4000 rpm although turbo engines tend to always make peak torque around the same RPM peak boost is achieved earliest. I've attached the dyno plots to show what's going on. At low boost, 10 psi and below the engine is able to rev nicely, probably to 6000 rpm as you can see. Anymore boost and it hits a brick wall as you can see. At 3750 rpm it's making 710Nm of torque and you can see in the video below what the car does when WOT is applied at this rpm (1:05) ... tries to kill me haha. (Ingore the squiggles as it comes up to full power as it was wheel spinning on the dyno and confusing the dynomachine).





With this vacuum tank - anyone got a picture of this little device?

Harvey, this is how it's driven on the track, you can see the RPM's I use. http://www.youtube.com/watch?v=qssbthwIb4s

My desired RPM range will be from 5000-7000 rpm. Aiming for a very flat torque curve and an increasing power curve... similar to Porsche GT3's:

You probably have worked all this out by now. Watching that vid tell me a lot about how this car handles the torque that it has now, and I wonder how you will get the torque to the ground when it extends right through the rev range. I think you will have gear it up to make use of the torque or it will just spin. Anyway that will be your problem.

The rev range that you want to use is OK and can be filled without too much problems. It basically needs as much lift as you can safely give it. 8.75mm is the limit with hydraulics, so you really need to go to solids and about 10mm or more. This will let it keep filling the cylinder to let the torque continue up the range.
The exhaust timing needs to open earlier to allow the cylinder time for the pressure to blow down, you can just advance the timing to open at 65*BBDC, or if you are doing new cams, add 10* to the duration and set the lobe center at 103*. As the exhaust energy is consumed driving the turbine, there is nothing to be gained on the overlap from resonate waves from the exhaust.

The Inlet. This depends on if you use the Inertia system, I know that you probably think this is too low in the rpms to be useful, but this car will always have a lot of torque, and the further up the rev range you operate, the harder it will be to get it to the ground. If you want to use it, then you keep the 240* duration, retarded 10* to let it extend the torque up the range a bit to fill the 6000 to 7000 bit.

If you don't want to use the Inertia system, and you are doing a cam for it, then add the 10* to the duration, and you can either change the lobe center to retard the valve closing further, for more up the higher rpms, or add the extra to the overlap, to blow some E85 across the exhaust valve to cool it.

It would be worth trying switching the inertia system in to try it as the car is now, you will find that the torque will run from about 2500 up, which gives you a wider rev range. You only need to have it turn on at 2200 and off at 4000, if you have a spare output, or just use a switch to turn it on, and see what it is like up to 4000.

As you are doing this and I am not, the choice is yours, but I would set it up to run the torque from low down, where it is manageable, and let to run up through the revs. This may not suit the ratios that are in the box, as it is set up for a narrow torque spread, so they are close ratios, to keep it on the boil. The advantage that you should have is the torque to jump out of the corners and run hard down the straights using the strong torque spread to do the job. The same as you would do if you had a larger capacity V8.

Harvey.

[bazza]

Originally Posted by oab_au

You probably have worked all this out by now. Watching that vid tell me a lot about how this car handles the torque that it has now, and I wonder how you will get the torque to the ground when it extends right through the rev range. I think you will have gear it up to make use of the torque or it will just spin. Anyway that will be your problem.

Hahaha yeah it's got a lot of torque. Although it was my mistake that the car got crossed up where it did. For the other 60 odd laps I never put a foot wrong. As I've been discussing with Tony, controlling power is rather easy with the array of electronics in the car - traction control, boost control, ignition maps, DCCD etc etc. Then add the rest of the aero, the 275 semi slicks and it's a fair effort for the car to break traction when driven properly.

As you are doing this and I am not, the choice is yours, but I would set it up to run the torque from low down, where it is manageable, and let to run up through the revs. This may not suit the ratios that are in the box, as it is set up for a narrow torque spread, so they are close ratios, to keep it on the boil. The advantage that you should have is the torque to jump out of the corners and run hard down the straights using the strong torque spread to do the job. The same as you would do if you had a larger capacity V8.

Harvey.

Thanks for the information on the cams - it will come in most handy. I'll keep you updated as to how it goes.

[bazza]

Originally Posted by dynomatt

Just wanting to subscribe to this thread.

Harvey we've discussed this before. FWIW, if was building another engine I'd be considering more lift (like closer to 12mm), more duration (closer to 275 or 300 seat to seat), bigger valves, higher compression (12 or 13:1)etc.

And adjustable wheels so static timing can be perfect.

I think the combination of those would be a pretty handy racing application...not a torquey luxo barge setting.

Matt

Do you have your current cam specs? Also I was chasing that old dyno graph that you did when you put them in with the throttle bodies vs the iris valve.

Can someone also clarify - do the hydraulic buckets reduce the effective duration? For example if I have a 272 duration cam in a solid bucket vs a hydraulic bucket - is the actual duration still the same or due to the ramp effects of the hydraulic is it really 30 degrees less?

[oab_au]

Originally Posted by bazza

Do you have your current cam specs? Also I was chasing that old dyno graph that you did when you put them in with the throttle bodies vs the iris valve.

I don't think that one got on the dyno. It only had the throttle bodies and exhaust. The one with the solids and cams did.

Can someone also clarify - do the hydraulic buckets reduce the effective duration? For example if I have a 272 duration cam in a solid bucket vs a hydraulic bucket - is the actual duration still the same or due to the ramp effects of the hydraulic is it really 30 degrees less?

There is not a lot of differences in the ramps for the solid and hydraulic cams. The solid cam’s ramps have to start slow to take up the tappet clearance, before the lift starts, the hydraulic has no clearance so the ramp is faster.
The loss with the hydraulic is at the end of the lift. The lifter is bleeding down while it is lifting, so by the time that it is closing it has loss enough lift, to close early.

The main problem with quoting the duration, is where the timing is measured from. There are a number of standards. US start when the valve is 0.050” off its seat, the JAP, European is to start at 1mm/0.040”, and then there is the engine builders measurement of 0.002” off the seat., for the ‘seat to seat’ measurement. So to eliminate the differences caused by the different types of ramps, the advertised durations are given at 0.050”/0.040” lift.

Harvey.

[bazza]

You are certainly a wealth of info mate. Okay let's design a cam to get made up. 264 duration intake and exhaust, slight port to suit cams, stock valve train, prolly spring upgrade so 8.75mm lift. Don't care about idle. 235 duration at 50 thou. Do you think it would rev to 7000 rpm, would 272 work better?

Where would you open close intake and exhaust for this setup and what centrlines would you run?

Also assume no iris and flat torque from 4 to 7.

Hoping to have something made

[bazza]

RB20's (6 banger Nissan motor) are hydraulics from what I can tell... they seem to run up to 9.5 mm. A lot of duration by both Camtech and Kelford. Why is our limit 8.75 mm? Is this a spring limitation?

Camtech:
http://www.camtechcams.com.au/niss_6...b25nonvct.html

Kelford:
http://www.camshaftshop.com/products...tid=1048#specs

[bazza]

Wonder if it's worth buying:

http://performancetrends.com/ca20.htm

[bazza]

Spoke with some expert camshaft people and they've mentioned several things. Hydraulic buckets good for 10,000 rpm as in their own racecar.
No issues running a lot of lift with correct spring.

I trust these guys as I've used their cams before and they're simply brilliant so I am going to ship my cams to them and see what they can come up with.