ptuomov

Here's an attempt at a quick survey. There are a number of high-performance 928 engines out there at this point making impressive power. Who's got the highest revving engine? I am intereted in how high are people comfortable reving their expensive engines, and where they have set the redlines. Furthermore, what changes were necessary to get the motor to hold at the high revs, especially the short block? How should one build a reliable 928 engine that is capable of running at high RPMs reliably for many thousands of miles and many many hours.

To set some bounds, only 928 engines qualify. Also, only engines that have actually been run qualify, my project and other such I'll-run-a-dry-sump pipe dreams don't. To soften that a bit, a separate category for ongoing projects. Finally, there has to be some reliability expectations, it's not enough just to remove the rev limiter!

IcemanG17

With the exception of Mike Simard.....not very many stroker 928's rev past 7000, or make power past 7000....... Mike used Ti rods to keep the rotating weight down enough to allow such RPM's...... I think Anderson can rev to 7000 under racing condtions....but doesn't have too....most shift around 6500 or so....

Heres some applicable calculators
http://www.wallaceracing.com/piston-speed-velocity.php
http://www.wallaceracing.com/Calcula...-of-Piston.php
http://www.slowgt.com/Calc2.htm#PistSpeed
http://www.slowgt.com/Calc.htm

Z

Sorry I don't remember the exact numbers offhand, but of the ones that I've heard of so far, the highest is one going somewhere over 8,000 RPM, and making over 800hp up there. That was the crankshaft horsepower, not rear wheel horsepower, as measured on an engine dyno before the engine was installed in the car. The engine's normally asprated, right around 6.5 liters, is steel sleeved, has an individual throttle body type intake, with coil on plug ignition.

I forgot most of the stuff that one of the mechanics who was involved with that project told me about the details of the engine the last time that we were talking about it. I'll probably see him over the Labor Day weekend, and will try to remember to get some more exact numbers from him again then.

mark kibort

25 race days so far. all racing shifts at near redline 6500rpm. (6600redline)
power curve doesnt pay to shift higher even if I could.

Andersons power curve does, however.

mk

largecar379

cam buckets and the timing belt are the limiting factor.

solid buckets will extend your range upwards of 8000 rpms plus. Greg Gray is using solids in his 16V engines down under.

I have a contact that builds buckets for high HP/rpm record holding ricer engines that will guarantee an additional 1k rpms over the stock hydraulic buckets---I know, you said 928 only but he will make some for any engine including 928--he doesn't care what you're building.....

very good pieces, very expensive.

the was talk some time ago about a new Gates belt that is reported to be much stronger--as to higher rpms....I can't say. not enough info as yet.

rpms do not come cheap.....

--Russ

GregBBRD

I generally move the rev limiter to 7500 when I tune, on my custom engines, although there is little reason to rev these engines this hard. We are severely "camshaft" limited and most of the engines are well past the place where it makes sense to shift, long before this.

Louie928

My "soft" rev limiter is set to 6600 RPM and I hit it sometimes, but try not to. Steel rods, no special lightweight internal parts. HP curve is still climbing at 6600, but I don't want to risk breaking anything by going higher to find the peak. The "stroker" engine blocks do have a tendency to crack. The solid spacer between the engine block and oil sump I devised should help stiffen the block, but I don't have the funds to be experimental. Don Hanson with the same internals except he had Ti rods ran his to 7200 RPM.

Brett928S2

Hi

Standard 928 S2 engine - 310hp (no work done and 142,000 miles)

Rev limiter moved up to 9710 by John Speake.

Have run at over 8000 a few times on Nitrous...but only for 10 to 15 seconds a time....no problems at all..

My shift lights are set at 7500 so I can shift then if I wish...

I seem to gain no more power over around 7800 so I usually shift at somewhere around 7700 ish...

All the best Brett

RKD in OKC

So...is that why Mark Anderson is having trouble keeping tranny parts in his car now, using the more powerful top end of the rpm range?

smudaaar

Without having solid lifters or high compression 12-13:1 our engines will run out hp b4 they hit 7k! A balanced and Blueprinted BBC will hit 9-10k. If you have the funds anything is possible!

John Veninger

6.5K for me.

danglerb

Doesn't torque effect the tranny more than HP?

Maybe I remember wrong, but didn't MarkA run his 16v motor over 8k?

Below is a cut and paste from JME racing,

8SR-14 for 944 performance/928 race
Best power band 4000-6900 rpm. 1000 rpm idle. .503 cam lift (In & Ex) with near stock base circles. Uses 944 Turbo or race valve springs (recommended) for best results. Motronic chip must have rev limit raised for best results. 25+ bhp over stock camshaft with race exhaust. Needs custom Motronic chip or aftermarket engine management. No equivalent competitors cam. Used where lift is un-restricted but racing cam is allowed.

B13-10, B13-14 for 944 race/928 race
Best power band 4400-7200 rpm. 1100 rpm idle. Off idle lope. .539 cam lift (In & Ex). Modified hydraulic lifters required. Race valve spring & retainer package required. Motronic will not work. Bhp available depends upon tune of engine. No equivalent competitors cam. Used where lift is un-restricted but racing cam is allowed. RH B13-10 has better midrange power, RH B13-14 has better top end power.

Race Solid Lifter RS 304M2/280M-10 for 944/928
Best power band 5000-8200 rpm. 1300 rpm idle. Off idle lope. .595 cam lift In, .510 Ex. Race solid lifter, valve spring & retainer package required. Motronic will not work. After market engine management only. Bhp available depends upon tune of engine. No equivalent competitors cam. Used where lift is un-restricted but racing cam is allowed. Best results with unrestricted intake, fully ported cylinder head with larger valves, racing header.

LT Texan

ptuomov

Simard's machine is impressive. It's a stroker and strokers' have a lower natural redline yet he's comfy running it to 7500rpm. The max piston speed increases approximately proportionally to the stroke. The inertial rod forces increase approximately proportionally to the square of the stroke. Keeping the rod strength constant, the reciprocating parts will have to be lightened by a factor of (old stroke / new stroke)^2. So increasing the stroke from 78.9 to 95.5 (or whatnot) increases the piston speed by 21% and (at constant strength) requires 32% weight reduction to the reciprocating components.

Based on this math, with the standard 78.9 stroke, one could run Simard's short block much higher, at least to 9000 rpm. His dry sump etc. might really make this possible in reality as well.

There's some confusion about Anderson's rpm range. Anyone with audio files from the track who's counted his shift points? ;-) I guess we could just ask him.

Sterling, how did you determine the number 7200 rpm? I am looking at your short block and I don't understand what would limit you to 7200 rpm. Is it all valvetrain that is limiting you? Or do you mean that you get no benefit from spinning above 7200 rpm?

Please find out more, especially about the short block.

You need new cams. With all the time you spend doing what you do, don't you think it would be worth it to drop some cash on a regrind or even a welded and reground cams? You are suffocating a young, perfectly innocent baby of a short block.

I would disagree about the hydraulic buckets. The lightweight hydraulic buckets made for Volkswagen spin happily up to 8300 rpm in Volkswagen engines. The hydraulic lifters may limit the cam profiles a bit for various reasons, but basically they'll hold higher rpms than what any of our strokers see.

That's Roger's project and I am waiting eagerly for one. He also sells the VW lifters and the stronger cam chain. All that is left after the timing belt on that side is a reinforced water pump.

I believe you build strokers, correct? Ignoring the valvetrain for a second, if you can reliably run your strokers to 7500, what's the limiting factor in not running the stock short block to much higher? Is it that damn rod bearing oiling issue in the stock crank? Or is it the better oil retention of the Nikasil surface? Or are your pistons and rods so much lighter than the stock components? Are the piston skirt and bore hone designed to give a much smaller surface area? Or all of the above? Maybe these are business secrets, but I am very interested in whatever you can divulge about your short blocks.

I've seen your dyno curve and it's like damn, that thing would make insane power for another 1000rpm at least.

How often do the stroker blocks break? Is this because of the longer stroke or because of something else?

Your spacer: Are you talking about just the oil pan spacer ring or a whole web a la Simard?

And no problems? How many hours have you run that thing above 7500 rpm?

I think it's the combination of engine side torque with slicks more than anything that kills trannies.

Those 9.5k BBC's have everything purpose built, starting from the block. They have nothing really in common with the original big block Chevy engine. And they take this 9.5k redline speed for about a fraction of a second a couple of times per a quarter mile pass. Do you have an actual example of a 928 engine that has been built with the same philosophy and budget?

Why not higher? No benefit?

Let's see if he chooses to join the thread.

John Veninger

To costly!