Cam Lobes

[oab_au]

Originally Posted by SVXRide

Harvey,
I'll try to make some time to call Scott on Monday. Can you give me a little more to work with here, as the 205 deg at 0.050" appears to be the KA24DE intake (less a degree of duration)? Are we still looking at the KA24DE intake and exhaust profiles as our desired NA2 profiles? The thread has been a little disjointed at times due to the apparent variation within the KA24DE cam "family". Will the "255 deg seat-to-seat" spec be enough of a requirement to drive the "fast opening/closing ramps" aspect here?
Thanks.
-Bill

Sure Bill, this is the closest I have seen to what I want

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

2/3* on the 0.050" won't make a lot of difference, the Seat to seat measurement will depend on the opening/closing ramps, so it may be anywhere. The extra 20* duration at 0.050" is the important bit.

As we did with the first cam we did, we asked for 240* 8mm lift, what did we get, 247*almost 8mm lift. Sometimes you have to work with what you get.
Thats why we have to get Scott to tell us, what profile he has that is close to what we want. We can then decide on, which to use.

If Scott can give us the duration at lifts of 0.006", 0.010", 0.020", 0.030", 0.040", 0.050", we will know that the cam is actually like.

Harvey.

[SVXRide]

Originally Posted by oab_au

Sure Bill, this is the closest I have seen to what I want

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

2/3* on the 0.050" won't make a lot of difference, the Seat to seat measurement will depend on the opening/closing ramps, so it may be anywhere. The extra 20* duration at 0.050" is the important bit.

As we did with the first cam we did, we asked for 240* 8mm lift, what did we get, 247*almost 8mm lift. Sometimes you have to work with what you get.
Thats why we have to get Scott to tell us, what profile he has that is close to what we want. We can then decide on, which to use.

If Scott can give us the duration at lifts of 0.006", 0.010", 0.020", 0.030", 0.040", 0.050", we will know that the cam is actually like.

Harvey.

Harvey,
I just got off the phone with Scott and he told me he just got a new machine in that is much more accurate than his old machine. Unfortunately, it came with a 300 page manual that he hasn't dug through yet. As such, he can only do .050 right now. He promised to get on it and figure out how to get us the durations at the other lifts. He also said he'd check to confirm that the "Gold" version of the KA cams was the "hotter" version (versus the "Green" version). Stay tuned!
-Bill

[dynomatt]

Guys,

I'm in the process of getting my heads measured for some mods.

I thought it would be useful to share what I've learned. Most of it supports what's already been found out, but I plan on doing different things with the information.

At this end, standard cams have 192 duration at 50 thou inlet and 197 duration at 50 thou exhaust.

Inlet lifts to 7.1mm and ex to 7.82mm.

Give or take, that's the same as what you guys have got.

Intake port flows have been done, but in Australia we use 10" of water vs your 28" of water I think. So 10" water figures (you'd need to change them) are:

• 4mm - 84cfm
• 6mm - 123.8 cfm
• 8mm - 150.8cfm
• 10mm - 158.9cfm
• 12mm - 160.3cfm
• 14mm - 159.3cfm

Bigger valves and some porting work should see the max flow increase to around 185cfm or possibly more. Using conservative numbers, that means a potential NA power (in perfect conditions with throttle bodies, extractors etc etc...full race motor) in the order of 420hp. Real world that's probably closer to 370hp.

Based on that, and against a few peoples views (hi Trevor), we are going to go for a cam with 230 degrees duration at 50 thou (40 degree increase) and then 10-12mm of valve lift to suit max flow. Now, all of you would know that in order to do that, we'll need new valves and springs in order to get the lift. We'll also need to machine the head to clear the lobes. The profile is from a Volvo touring car.

We believe that by keeping the duration as close to standard as possible, most of the low end torque will be retained (in fact, EAPro supports this) but then the top end power (up to 8000rpm is the target) will have a large increase.

The exhaust flows diffeently. It has the following:

• 4mm - didn't get them
• 6mm - 98.1cfm
• 8mm - 109.8cfm
• 10mm - 113.8cfm
• 12mm - 116.7cfm
• 14mm - 118.3cfm

The ratio of flow is a little low, hence the factory has given the exhaust cam a bit more duration. That's possilby what we will do too, if we can find a suitable profile.

What do you guys think about this?

Matt

[Trevor]

Hi Matt,

My views have been based on cost/effect. It would now appear that cost is no object and you are therefore in a different ball park. Yes at a price, you can go for a wide power band. Larger valves are a sound idea, but I still caution you regarding the increase in lift you have in mind.

Best of luck, Trevor.

P.S. You have done the right thing in researching as many cams as possible.

[dynomatt]

Cost is certainly an issue Trevor!! I've found somebody who won't bend you over when he charges you, and does a very good job.

I think there's actually a few steps you could evaluate.

1) Evaluate what is possible with the standard springs. Ie, find a profile that probably has longer duration to compensate for the low lift. You'd want to limit duration to a max of about 240 degrees based on the 3 cylinder nature of the motor. Thanks Harvey for that tip. Cost = new cams.

2) New valve springs (as I think they are the only hold up) to enable bolt in cam changes. With new springs, you could hypothetically get to 10mm of lift, with a factory duration. That would make for a much more spirited top end (and probably go 75% of the way we want to go). Cost = new cams and springs

3) Full blown...big valves, port job, new seats, new springs, new buckets, new cams etc...big $, but big performance potential.

Matt

[SVXelerator]

Mr. Matt,
very interesting flow figures. What cylinder did you measure the intake and exhaust flows on? The center cylinder on either bank has a rather contorted exhaust flow path, compared to the two end cylinders.

[oab_au]

Originally Posted by dynomatt

Guys,

I'm in the process of getting my heads measured for some mods.

I thought it would be useful to share what I've learned. Most of it supports what's already been found out, but I plan on doing different things with the information.

At this end, standard cams have 192 duration at 50 thou inlet and 197 duration at 50 thou exhaust.

Inlet lifts to 7.1mm and ex to 7.82mm.

Give or take, that's the same as what you guys have got.

Intake port flows have been done, but in Australia we use 10" of water vs your 28" of water I think. So 10" water figures (you'd need to change them) are:

• 4mm - 84cfm
• 6mm - 123.8 cfm
• 8mm - 150.8cfm
• 10mm - 158.9cfm
• 12mm - 160.3cfm
• 14mm - 159.3cfm

Bigger valves and some porting work should see the max flow increase to around 185cfm or possibly more. Using conservative numbers, that means a potential NA power (in perfect conditions with throttle bodies, extractors etc etc...full race motor) in the order of 420hp. Real world that's probably closer to 370hp.

Based on that, and against a few peoples views (hi Trevor), we are going to go for a cam with 230 degrees duration at 50 thou (40 degree increase) and then 10-12mm of valve lift to suit max flow. Now, all of you would know that in order to do that, we'll need new valves and springs in order to get the lift. We'll also need to machine the head to clear the lobes. The profile is from a Volvo touring car.

We believe that by keeping the duration as close to standard as possible, most of the low end torque will be retained (in fact, EAPro supports this) but then the top end power (up to 8000rpm is the target) will have a large increase.

The exhaust flows diffeently. It has the following:

• 4mm - didn't get them
• 6mm - 98.1cfm
• 8mm - 109.8cfm
• 10mm - 113.8cfm
• 12mm - 116.7cfm
• 14mm - 118.3cfm

The ratio of flow is a little low, hence the factory has given the exhaust cam a bit more duration. That's possilby what we will do too, if we can find a suitable profile.

What do you guys think about this?

Matt

Matt I think you are reading too much into port flow numbers. Sure the port may flow, 160 at 12 mm lift, but that is not what is happening when the piston is pulling the air, in to the cylinder. The port air flow is at peak speed for 15*/20*, the rest of the time it is speeding up or slowing down.

It is the rest of the inlet period that has to work right. At lower engine speeds the air will flow at a lower velocity into the combustion chamber, because of the excessive lift, turbulence and fuel distribution suffers.

The exhaust doesn't need to be the same, as the inlet, as working pressures are different.

So it is really a case of trying to use the least amount of cam duration and lift that you can. This way the engine has the power it needs, and has the widest torque curve you can get. Using it for rally work, it has to be able to handle running higher revs for extended periods, and take a lot of abuse.

I know what is the easiest to race, between a wide torque curve and a peaky horsepower engine. The torque engine, never drops off the power band.
I always try to build the engine to suit the needs, rather than a Horsepower figure.

Harvey.

[dynomatt]

I understand where you are coming from.

Is there some information I can be pointed to that proves my theory incorrect? I'm happy to eat humble pie if wrong, but am pretty convinced this is the way to go.

My understanding is the factory torque curve is directly related to the cam duration. Therefore, all things being equal, if you could get the same 190 odd degree duration, but more lift, are you saying the engine would be worse?

Engine analyser pro shows that with more lift and the same duration, more power is available in the higher revs, but the low end torque curve is the same. Is EAPro not calculating port velocity and cylinder filling issues? I'd find that unusual but would accept it if there's other information.

Don't forget, in my case, I want a motor that is for a competition vehicle. I'm interested in getting as much power as possible, and if that sacrifices the bottom end (which increasing the duratino will) then I don't want that, but if I can keep it, and get more higher up, that's got to be good?

Matt

[oab_au]

Originally Posted by dynomatt

I understand where you are coming from.

Is there some information I can be pointed to that proves my theory incorrect? I'm happy to eat humble pie if wrong, but am pretty convinced this is the way to go.

My understanding is the factory torque curve is directly related to the cam duration. Therefore, all things being equal, if you could get the same 190 odd degree duration, but more lift, are you saying the engine would be worse?

Engine analyser pro shows that with more lift and the same duration, more power is available in the higher revs, but the low end torque curve is the same. Is EAPro not calculating port velocity and cylinder filling issues? I'd find that unusual but would accept it if there's other information.

Don't forget, in my case, I want a motor that is for a competition vehicle. I'm interested in getting as much power as possible, and if that sacrifices the bottom end (which increasing the duratino will) then I don't want that, but if I can keep it, and get more higher up, that's got to be good?

Matt

Matt forget the "humble pie" thing. No body is trying to prove you wrong. We are all trying to achive the same thing, we just come at the same problem from different approches.

Yes more lift on the same duration will increase the torque at higher rpms. This is what I tried to achive in the first cam. To keep the duration as close to 240* and increase the lift. This has been sucessfull in extending the torque futher up the rev range. As far as I can tell from the reports from thoes that have it, " it hits 4000 rpms then accelerates hard to auto shift." Even with this 1mm extra lift, there is a small loss in low speed torque. The designers got very close to the combination, of HP and torque spread.

There is a limit to how much lift you can get with a 240* duration. The acceleration rates needed, become too fast, for the valve gear. Stronger springs will offset it, but the resultant loads can pull valve heads off.

Harvey.

[dynomatt]

Harvey,

I intend to get decent valves in order to run this lift (obviously the standard ones won't work) so that's no problems.

A comparable motor (in some respects) is the Metro 6R4 rally engine from the Group B Metro rally car. It was a 2.5l V6, with throttle bodies and extractors which had a similar bore and stroke ratio. Bore was about 92mm from memory, so stroke would be about 60mm maybe. Anyway, by example, it used 13mm of lift on head flow figures that were almost the same as the EG33. I don't have exact cam duration information but it was up around the 260 degrees at 50thou. Obviously, the throttle bodies allowed this duration where the standard EG33 manifold will not. It revved to about 10,000rpm (go Cosworth! ) etc and made (in 2.5l form) 380hp. The 3.5l version which was used in rally cross made 500hp at 12,000rpm. Now, realistically, I'm aiming for max power to be at about 7500rpm.

The attachment shows what's possible with standard valves, using these flow figures and a 230 duration, 10mm vs 12mm lift profile. Now it's mathematical, not real, but it gives you an indication of what increasing the lift will produce (all other things equal). Based on that, you can see that the torque curve is virtually identical until the higher revs...what does this mean?

Where have I gone wrong?

Matt

[oab_au]

Originally Posted by dynomatt

Harvey,

I intend to get decent valves in order to run this lift (obviously the standard ones won't work) so that's no problems.

A comparable motor (in some respects) is the Metro 6R4 rally engine from the Group B Metro rally car. It was a 2.5l V6, with throttle bodies and extractors which had a similar bore and stroke ratio. Bore was about 92mm from memory, so stroke would be about 60mm maybe. Anyway, by example, it used 13mm of lift on head flow figures that were almost the same as the EG33. I don't have exact cam duration information but it was up around the 260 degrees at 50thou. Obviously, the throttle bodies allowed this duration where the standard EG33 manifold will not. It revved to about 10,000rpm (go Cosworth! ) etc and made (in 2.5l form) 380hp. The 3.5l version which was used in rally cross made 500hp at 12,000rpm. Now, realistically, I'm aiming for max power to be at about 7500rpm.

The attachment shows what's possible with standard valves, using these flow figures and a 230 duration, 10mm vs 12mm lift profile. Now it's mathematical, not real, but it gives you an indication of what increasing the lift will produce (all other things equal). Based on that, you can see that the torque curve is virtually identical until the higher revs...what does this mean?

Where have I gone wrong?

Matt

That is about the same increase that I saw, in the 7mm to 8mm increase. The torque peak didn't rise by much, but the torque did not drop off as fast, running into the 6000 range to increase the HP. But with that 1mm, there was a drop in the VE at about 3500. I'll run a few models, to show what I mean.

Takes me a while, stay tuned as Bill would say.

Harvey.

Harvey.

[SVXRide]

Originally Posted by oab_au

That is about the same increase that I saw, in the 7mm to 8mm increase. The torque peak didn't rise by much, but the torque did not drop off as fast, running into the 6000 range to increase the HP. But with that 1mm, there was a drop in the VE at about 3500. I'll run a few models, to show what I mean.

Takes me a while, stay tuned as Bill would say.

Harvey.

Harvey.

(Notice how patient I've been? )
-Bill (stock intake cams have arrived, waiting on inputs from the "SVX cam squad" before shipping them off to join their exhaust cam sisters at DeltaCams)

[Trevor]

Originally Posted by dynomatt

Harvey,

I intend to get decent valves in order to run this lift (obviously the standard ones won't work) so that's no problems.

A comparable motor (in some respects) is the Metro 6R4 rally engine from the Group B Metro rally car. It was a 2.5l V6, with throttle bodies and extractors which had a similar bore and stroke ratio. Bore was about 92mm from memory, so stroke would be about 60mm maybe. Anyway, by example, it used 13mm of lift on head flow figures that were almost the same as the EG33. I don't have exact cam duration information but it was up around the 260 degrees at 50thou. Obviously, the throttle bodies allowed this duration where the standard EG33 manifold will not. It revved to about 10,000rpm (go Cosworth! ) etc and made (in 2.5l form) 380hp. The 3.5l version which was used in rally cross made 500hp at 12,000rpm. Now, realistically, I'm aiming for max power to be at about 7500rpm.

The attachment shows what's possible with standard valves, using these flow figures and a 230 duration, 10mm vs 12mm lift profile. Now it's mathematical, not real, but it gives you an indication of what increasing the lift will produce (all other things equal). Based on that, you can see that the torque curve is virtually identical until the higher revs...what does this mean?

Where have I gone wrong?

Matt

Greetings Mat,

I note that your benchmark is the the 2.5 litre, Austin /Rover V64V engine, which is a V6 incorporating camshafts driven by two relatively short toothed belts. You on the other hand are faced with a single very long convoluted belt. The suggested lifts, spring rates and larger valves, will increase the valve gear torque loadings by in excess of fifty percent. With an increase in RPM, even more in respect of the power requirement.

A V64V engine was used in a special Rally car, the Peugeot Cosworth, but in this instance was changed for a 2.5 litre V6 Cosworth DFV engine, based on an Opel unit. The change was made as a direct result of unresolved cam belt breakages, experienced with the V64V. I continue to advise caution in respect of increasing the loading on the SVX cam drive.

You question whether increasing lift and or valve area will assuredly extend the power band in respect of RPM. Yes it will, any improvement in respect of breathing must do so. However the ratio of increase will fall off rapidly as the optimum is reached.

As is usual in this form of exercise, compromises are the name of the game and only you can make the final decisions. May the fat lady sing.

All the best with the project. Trevor.

[dynomatt]

Thanks Trevor,

I don't think I referred to it as a benchmark, purely an example of what is technically possible. And that was 20 years ago!

I'll do my own research, but apparently the cam belt issue was to do with the breakage after about 10,000rpm? There's one company in the UK who sells belts guaranteed to 12,000rpm.

I think, given our limit will be 8000rpm and Subaru had factory limits of 7500rpm (albeit with standard valve gear), we are still within safe and reliable limits.

350hp will be the target, and should be achievable. The bigger valves and cams will offer a flatter torque spread across more revs.

M

[Trevor]

Originally Posted by dynomatt

Thanks Trevor,

I don't think I referred to it as a benchmark, purely an example of what is technically possible. And that was 20 years ago!

I'll do my own research, but apparently the cam belt issue was to do with the breakage after about 10,000rpm? There's one company in the UK who sells belts guaranteed to 12,000rpm.

I think, given our limit will be 8000rpm and Subaru had factory limits of 7500rpm (albeit with standard valve gear), we are still within safe and reliable limits.

350hp will be the target, and should be achievable. The bigger valves and cams will offer a flatter torque spread across more revs.

M

The additional torque involved in the cam drive will be your problem, not RPM. You could well research the maximum lift which has been applied by others in respect of modified Subaru engines in general.

When the fat lady sings. Trevor.