How to make a 24v safely rev (and make power) to 8000rpms

[2mAn]

I know that some legit cams are needed, Im mostly curious if the valvetrain needs to be upgraded as well, and then what are some good cams. doesnt necessarily have to make peak at 8000, in fact if the shift went from peak at ~6250 and shifted up to peak being ~6750 and a progressive drop off with something like a 7500rpm redline, it would really open up the peak powerband

[Nisse Järnet]

I know that some legit cams are needed, Im mostly curious if the valvetrain needs to be upgraded as well, and then what are some good cams. doesnt necessarily have to make peak at 8000, in fact if the shift went from peak at ~6250 and shifted up to peak being ~6750 and a progressive drop off with something like a 7500rpm redline, it would really open up the peak powerband

That would probably happen with dual non vanos M50 cams.

[Nutzy]

That would probably happen with dual non vanos M50 cams.

Nisse, so you're not running an aftermarket damper or anything? What have you done re the oil pump sprocket nut?

[Nisse Järnet]

Nisse, so you're not running an aftermarket damper or anything? What have you done re the oil pump sprocket nut?

Thats correct.
I'm using the shaft upgrade kit on the oil pump.

[dereliiict]

Putting in to be schooled here for future reference.

Looking to do a fairly similar set up as you, Nisse.

Carry on gents.

[The Dark Side of Will]

ARP rod bolts & main studs, internally balance the rotating assembly to .02 grams, accompanying valvetrain and you'll be good to go

are the s54 rotating assemblies really balanced to such an accurate degree? i find it hard to believe a mass produced engine would get so much attention at the factory

NOTHING is balanced to .02 g... there are too many zeros in your spec.

The S52 crank has a horrible harmonic characteristic that really kicks off in the low 7000s. I suspect that the S54 isn't so well balanced, but they *have* engineered out the worst of the harmonics.

The right answer. It them them a LOT of engineering to do it as well.

[The Dark Side of Will]

s54 was designed around operating to 8k so thats why its easier, but they still have issues once you start putting alot of hrs at high rpm

Who'd have though rod bearings are consumables?

I'm not sure how much the M50 manifold would benefit, but WOT Performance's Jenvey multi-throttle setup would be a great place to start on the intake side. ;-)

[328ijunkie]

Again every S52 ive seen north of 7300 without a shit ton of work to make it do that, explodes.

Lay the S52 and S54 cranks next to each other. The S54 stroke is actually worse for high rpm/piston velocity (~1mm difference) but the counterweights/factory balancing are much better engineered. M52 crank stays together just because its only 84 vs 89.6mm. Balancing design is similar.

[jalopi]

NOTHING is balanced to .02 g... there are too many zeros in your spec.

how exactly do you think f1 engines and motorcycles hold up to sustained RPMs for so long? the answer is a really, really good balance job.

actually i wouldn't be surprised if f1s' tolerances were tighter than that

[digger]

Probably something to do with really short stroke, really light and stong parts, lots of engineering and testing. I don’t know what they balance to but balancing at 0.02g vs 0.2g isn’t going to make much difference if the thing aint designed correctly for the intended application.

[LJ851]

I'm going to agree with digger, balancing to that small of a number will have no effect on longevity.

There is a fluctuating amount of oil clinging to all these parts spinning and reciprocating, effectively negating that fine of a balance anyway.

[jalopi]

to be fair, jim (the dude who owns that shop) once mentioned in a forum post that while he does balance every rotating assembly he gets to .02g, if he loosens the flywheel and shifts it only .1" + tightens it back up, the balance can show up to 5g.

point is, the closer you initially get it to zero, the better the assembly will handle extra shit on it later on

[digger]

point is, the closer you initially get it to zero, the better the assembly will handle extra shit on it later on

yes, diminishing returns though...its not like if you had perfectly balanced in the shop that its actually perfectly balanced when running. and a perfectly balanced assembly moves alot due to gas forces in a running engine. forces are forces balanced or not. The shorter stroke engines don't cope with more rpm because they are better balanced