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

[2mAn]

Just wanted to get input from those who've modified these things more than the typical bolt ons. Im assuming the bare minimum is a set of cams and valve springs.

My dyno (and Im sure many others) show the power peaking around 6200 rpms, so Im wondering what it would take to get another ~1000rpms and how to have the car keep making power that high

Looking for some real world input so I can dream about what I might be able to do in a few years :yawn:

[mpowerful]

To make power up that high youd need some serious head work. Plainly put its at the limitations of flow so the only way to get anymore out of it a lot of chamber/valve/port work.

[berlow94]

Aside from the head not flowing that great, you would need to convert to solid lifters. Your better off just getting an S54. Its a waste of time and energy on an M/S-50/52

[328ijunkie]

Most of the FBO M52s we do tuned and whatnot peak around 6500 and slowly taper down. I have reved my personal track/drift car as high as 7800 for a while. Doesnt really make power up there without cams (more aggressive than S52s). The valvetrain isnt the problem as much as the bottom end. Things get hairy above 7300 for the crankshaft. Dampened M52 cranks can take this (for a while). Mine consumed M52 Dual Mass flywheels every 9 months or so at that RPM point.

Moneyshifted it to around 7500 and bent and then dropped a valve a few months ago on track. You can rev up forward to 7500+ but overrevving the other way slacks the chaindrive and ruins everything :P.

Got another motor and am going the SC route to use the high revs. Will be revving to 8k with a rotrex blower and this:

To keep the flywheel lunching to a minimum and keep the crank happy.

[Nisse Järnet]

I have been revving 7500-8000 rpm since 2011 without issues, M50B28 turbo :)
No problem with power output on high rpm or using hydraulic lifters, i just have ST valves, ST springs, PPF cams and a light polish done to my head.

[Nisse Järnet]

If you want to keep it simple, a safe way is to use a M50B25 non vanos engine, they can rev 7000-7500 rpm stock but will not make power up there. To fix this cheap is to get another M50B25 non vanos intake cam and put on the exhaust side (needs minor machining to fit) this way you have power to at least 7000rpm.

[mpowerful]

Forced induction does trump head flow issues.

[nrubenstein]

Also, the S50/52 bottom ends will not hold up at those revs. Easier and cheaper to go S54 or S50B32 (euro).

[jalopi]

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

[nrubenstein]

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

For the low, low price of 2-3x an S54!

[Nisse Järnet]

If you go with 2.5 or 2.8 the bottom end is just fine but then you loose some displacement obviously :P

[jalopi]

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

[nrubenstein]

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

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.

[2mAn]

Well, the good news (for me anyways) is that my M52 was balanced and had a close eye on the weights of every rotating part. Flywheel is also a semi lightened M20 (~12lbs IIRC) attached to the G260

and obviously forced induction helps, but thats not the point of this

[digger]

head flow is not that much worse than the s54 from data ive seen but a proper port job aint gonna hurt. however OEM cams are pretty girly, get some decent ones if you want power sincve the valves need to be open for the head to flow. by looks of it the OEM plastic intake manifold is far from the best, a better intake runner setup and plenum would be worth power especially on a built engine.

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