Anyone done a higher rpm build?

[catpat8000]

There are a couple of stroker options out there: Dinan and RD. I also see that VAC offers a 4.4 Liter stroker kit.

But has anyone gone down the route of a high rpm stroker build? Could an engine like this be set up to run reliably to 9000 rpm, say using the 4.4 liter kit?

If so, and with some head work and more aggressive cam timing (Schrick anyone?), it seems like it might be quite an interesting project.

[Someone?]

I would say 8600rpm would be plenty, even with bigger cam w/ bigger displacement i doubt it would make more power at the higher rpm.

[catpat8000]

Originally Posted by Dashman

+1

The small amount of HP you reap at the top end isn't worth the added stresses to the engine

I think it might make more power than you think at higher rpm.

Current engine makes ~275lb/ft @ 8000rpm = ~420 hp

With a 10% larger displacement, more aggressive cam timing, some headwork, exhaust, etc, if you saw ~300 lb/ft @ 9000 rpm, that's 515hp.

The point of the exercise would be to move the torque curve up in the rpm range, while strengthening the engine to handle the additional rpm.

I started thinking along these lines reading about the Ferarri 458 Italia engine, which is quite a miracle: 4.5 liter V8, 14:1 compression ratio and 605 hp @ 9000 rpm.

RPM is power, if your engine can hold together.

[Ezio]

Originally Posted by Dashman

+1

The small amount of HP you reap at the top end isn't worth the added stresses to the engine

keeping in mind you are building for high RPM. which means you are putting parts in there that can handle it

[Ezio]

i dream about a 9k redline M3 that is build to make power there also.

[regular guy]

Originally Posted by Ezio

keeping in mind you are building for high RPM. which means you are putting parts in there that can handle it

+1

Stock valve springs are a weak link. Call Dinan, RD Sport, or Auto Talent for better valve springs. Stock springs have rather weak seat pressure, which means you might hit valve float sooner than you want. I think the factory valve springs were tested to 10000, but with the numbers we tested for seat pressure, I wouldn't want to run them any higher than stock.

[spool twice]

is a stroker kit + higher rpm build possible? Keep in mind that piston speeds are greater per given RPM with a longer-stroked displacement.

[catpat8000]

Originally Posted by spool twice

is a stroker kit + higher rpm build possible? Keep in mind that piston speeds are greater per given RPM with a longer-stroked displacement.

The possibilities will be defined by the specifics of the pieces. I don't know the answer.

But in general what matters in the bottom end with respect to rpm is not piston speed, although that is a short-hand people on the internet seem to use, but the acceleration of the pistons and con rods as they move up and down. They are accelerated by a force and this force is what causes stress and strain on the components. If the mass is reduced, then the forces applied are also reduced (at a given rpm), and in a linear way. This can allow for more engine rpm and/or a longer stroke. So, for example, this is why the Corvette Z06 and the 911 GT3 and the 458 all use titanium connecting rods.

Also, it's worth noting that BMW built its own S65 stroker with the 4.4 liter GTS. And didn't they keep the same redline?

As for the top end, building a 9000 rpm engine would need to consider the valvetrain, what springs to use, whether lighter valves were needed, etc, etc.

Finally, you'd need to make sure the intake and exhaust didn't prevent the needed breathing at 9000 rpm and you'd need different cam timing to move the torque curve higher in the rpm range.

I completely admit I'm an internet/arm-chair engine designer but, nonetheless, I don't think this engine is out of the realm of possibility.

[Brian_VACsales]

Originally Posted by catpat8000

There are a couple of stroker options out there: Dinan and RD. I also see that VAC offers a 4.4 Liter stroker kit.

But has anyone gone down the route of a high rpm stroker build? Could an engine like this be set up to run reliably to 9000 rpm, say using the 4.4 liter kit?

If so, and with some head work and more aggressive cam timing (Schrick anyone?), it seems like it might be quite an interesting project.

Yes, you can run a 4.4L past redline if the supporting parts are in place. (as mentioned up thread)

Side note: We developed and built a 3.5L S65 crank/rod/piston package. Hope to test it this winter with Schrick valvetrain ;-) 9500 RPM+++

We stock all of the Schrick S65 parts that are proven well past factory redline.

[larouchemk]

i doubt it would make more power at the higher rpm.

[Ezio]

Originally Posted by larouchemk

i doubt it would make more power at the higher rpm.

the random guy with 4 posts usually know best

[Hujan]

Originally Posted by Mike@VAC

Yes, you can run a 4.4L past redline if the supporting parts are in place. (as mentioned up thread)

Side note: We developed and built a 3.5L S65 crank/rod/piston package. Hope to test it this winter with Schrick valvetrain ;-) 9500 RPM+++

We stock all of the Schrick S65 parts that are proven well past factory redline.

Very interesting. How did you reduce the displacement from 4 to 3.5 L?

[regular guy]

Originally Posted by Hujan

Very interesting. How did you reduce the displacement from 4 to 3.5 L?

Lower the stroke is one way, sleeve the block is another.

65.8mm stroke x 92mm bore (stock bore size) = 3.499 L
75.2mm stroke (stock stroke) x 86mm bore = 3.494 L

Or do both and square up the engine:
82.25mm stroke x 82.25 bore = 3.496 L

[like2short]

Originally Posted by Mike@VAC

Yes, you can run a 4.4L past redline if the supporting parts are in place. (as mentioned up thread)

Side note: We developed and built a 3.5L S65 crank/rod/piston package. Hope to test it this winter with Schrick valvetrain ;-) 9500 RPM+++

We stock all of the Schrick S65 parts that are proven well past factory redline.

Sounds like a s54 c-mod killer engine

[Longboarder]

Originally Posted by catpat8000

I think it might make more power than you think at higher rpm.

Current engine makes ~275lb/ft @ 8000rpm = ~420 hp

With a 10% larger displacement, more aggressive cam timing, some headwork, exhaust, etc, if you saw ~300 lb/ft @ 9000 rpm, that's 515hp.

The point of the exercise would be to move the torque curve up in the rpm range, while strengthening the engine to handle the additional rpm.

I started thinking along these lines reading about the Ferarri 458 Italia engine, which is quite a miracle: 4.5 liter V8, 14:1 compression ratio and 605 hp @ 9000 rpm.

RPM is power, if your engine can hold together.

Originally Posted by regular guy

+1

Stock valve springs are a weak link. Call Dinan, RD Sport, or Auto Talent for better valve springs. Stock springs have rather weak seat pressure, which means you might hit valve float sooner than you want. I think the factory valve springs were tested to 10000, but with the numbers we tested for seat pressure, I wouldn't want to run them any higher than stock.

Originally Posted by spool twice

is a stroker kit + higher rpm build possible? Keep in mind that piston speeds are greater per given RPM with a longer-stroked displacement.

Originally Posted by larouchemk

i doubt it would make more power at the higher rpm.

All good posts.

I've been thinking about this since I did my first supercharged dyno and noticed how the torque "curve" barely tapers off at redline. Imagine torque continuing until 10K rpm. That would give you well beyond the power of anything made today with the exception of the few hypercars out there...and quite possibly would be as powerful as the VT3 builds of DLSJ5 and IMG/BLUDEVIL....just in a different way of going about it (less boost, more RPM). I think the advantage of higher RPM vs higher boost is a car that is less susceptible to wheel spin since peak torque would be down significantly.

Forget about doing this to a completely stock motor...torque would fall off too much so larouchemk is right...it just won't make any more power regardless if you get it to rev higher. A N/A motor revving beyond 9K will need cams which means you will likely sacrifice even more low end power which is already lacking in the S65. There is at least one other member (can't recall who at this point) who has done cams and I think it was on a supercharged motor but I don't remember who or what RPMs it revved to. I don't think it was much higher than stock though.

For a supercharged S65 revving to say 9.5K, I wouldn't think cams are actually necessary as the blower will keep making more boost at every RPM increase so theoretically with some valve springs that wouldn't float, and some stronger internals (rods in particular) I don't think it will be that difficult to get a S/C S65 to rev higher particularly as regularguy notes, BMW has already tested the motor to 10K.

I have been thinking about this for some time but will put it off for a while as I embark on a project for another car of mine. Hopefully somebody else tries it first.

Longboarder dyno stock vs supercharged:

[catpat8000]

Originally Posted by Longboarder

I've been thinking about this since I did my first supercharged dyno and noticed how the torque "curve" barely tapers off at redline. Imagine torque continuing until 10K rpm. That would give you well beyond the power of anything made today with the exception of the few hypercars out there...and quite possibly would be as powerful as the VT3 builds of DLSJ5 and IMG/BLUDEVIL....just in a different way of going about it (less boost, more RPM). I think the advantage of higher RPM vs higher boost is a car that is less susceptible to wheel spin since peak torque would be down significantly.

This is a very interesting idea - building an engine to tolerate high rpm and then supercharging it with only moderate boost. I agree the torque curve looks flat to increasing all the way to redline, unlike the pure stroker. Another advantage this moderate boost approach would have over a high boost approach is that it means less risk of damaging DCT or LSD or other drivetrain parts for a given HP output due to lower peak torque.

Pat

[Longboarder]

Originally Posted by catpat8000

This is a very interesting idea - building an engine to tolerate high rpm and then supercharging it with only moderate boost. I agree the torque curve looks flat to increasing all the way to redline, unlike the pure stroker. Another advantage this moderate boost approach would have over a high boost approach is that it means less risk of damaging DCT or LSD or other drivetrain parts for a given HP output due to lower peak torque.

Pat

My project stalled as others mentioned the DCT trans cannot rev much past 8,800 RPM. I have no idea whether this is true or not, but if going forward with a build where RPM will substantially higher than this, I would call the manufacturer (Getrag) to see whether going beyond 9K is possible. Good luck.

[dparm]

Originally Posted by Longboarder

My project stalled as others mentioned the DCT trans cannot rev much past 8,800 RPM. I have no idea whether this is true or not, but if going forward with a build where RPM will substantially higher than this, I would call the manufacturer (Getrag) to see whether going beyond 9K is possible. Good luck.

Ferrari is going to 9k on this transmission family, right?

[Longboarder]

Originally Posted by dparm

Ferrari is going to 9k on this transmission family, right?

Yes the Italia uses the Getrag 7DCT. Not sure whether the internals are any different.

[dparm]

Originally Posted by Longboarder

Yes the Italia uses the Getrag 7DCT. Not sure whether the internals are any different.

It's a different unit, but the same family as ours.