Fastest928

Gee Lag,
Your statement

"A working full-meal-deal 6.5L comparitively did 'only' 550 rwhp"

way off course!

A full race 928 6.5 would make a minimum of 650 rwhp. My engine at 500 rwhp uses no, read that ZERO race level technologies...no race cams, no raceheads, no lwt internals, no fricition reducing technology, no dry sump, no intake, etc.

Wait, that same engine made 550 rwhp with small intakes, and Dons with my intakes made 576+ rwhp. And that is with Ti rods, lwt pistons and NiSi bores...but still with our B1 cam set which is only a 235 Degree duration cam with 11mm lift...not a race cam by any means. Right, you must know that. The B2 cam would be a far beter choice.

BTW, go look at the 550 curve again....notice anything about the torque curve at 6100 rpm, or how about 6200, or what do you think it was doing at 6500, or 7000 rpm? Opps, dont think because you do not see all the dyno graphs that that is all there is

BTW, a long time ago, we had a stock 5.0 l street engine at 353 rwhp. using ported and 39 mm street level heads, B1 cam and headers with cats. Very lopey, and not stable below 1000 rpm, but sure screamed till 7K. Hmm, how much engine hp is that? Turn that inot a full race engine and gues what?

So, 600chp in a 5.0 is very attainable in a race engine.

In conclusion, you just do not know what make a "fully massaged race engine". Dont feel bad, most folks who have never built a pure race engine just do not know the difference bvetween a modified street engine and a race engine.

Hey, I think we have a sale on head gaskets coming up soon that you might be interested in .or are you now using the cometec gaskets?

Marc
DEVEK

the flyin' scotsman

Marc............was curious as to your thoughts on 1000cc motorcycle engines making +150 HP and the reasons why Porsche 928 engines (or any other car engine manufacturere for that matter) at 5x the size do not make 5x the power; 750 HP. It would seem to me that Honda, Suzuki, Kawasaki and Yamaha can all build 4 cylinder, 4 (5) valve per cylinder engines capable of this type of horsepower, reliably, economically while all the time NOT being full race engines.

James-man

The issue may not be the ABILITY to make a fully developed 928 race engine. It is probably more about the willingness/desire and funds for anyone to do so.

If highly strung race engines generally have a short half life, I can't imagine anyone wanting to run the risk of blowing, pulling and rebuilding these engines more than once a season... without a sponsored team.

Until someone is willing to have a fully developed race engine built, the high HP potential is only theoretical. To answer the gentleman's initial question, you should estimate HP for the current state of development of 928 engines. What can be built within the next couple of months using existing parts that have already been developed/produced (cams that have actually been built, existing exhaust technologies, porting that has been done, etc).

The HP potential should be based on currently available technology and should assume no infinite development budget. Those with infinite budgets would probably choose a different platform than the 928.

Lagavulin

That's the only dyno sheet I've seen of yours.

Yep, I know that, I've read your other posts. As you well know, talking is one thing, and doing is an entirely other matter.

I know about Don's engine, but didn't mention it since you didn't build it.

I told you when you first posted it that I like it, and I still do; again, good job!

I'm not doubting it (..reasonable numbers), but a dyno sheet would be appreciated...

By the way, 353 rwhp is what my stock 2v Z06 puts down, idles with a slight shake at 800 RPM, and would probably pass emissions at WOT.

What?

353 rwhp / .85 = 415 crank hp

600 chp - 415 chp = 185 chp difference

Your 'claim' is 600 at the crank for 5.0L. It looks like to me you're only 185 crank hp short of attaining that. I guess what you're trying to imply here is that with 39mm 'race' level heads, an B2 cam (..how much bigger than B1?), and 'Marge', you'd be able to pick up another 185 at the crank from a 5.0L. I seriously doubt it as there is too much ground to make up with only 5.0L's.

Respectfully, I do not agree.

Your assessment is somewhat true, but principle-wise, I fully understand what makes for a 'fully massaged race engine', versus a street engine.

On a slightly different note, it appears to me that you are implying that your 550 rwhp engine is a 'street' engine; I beg to differ. Firstly, you had to trailer the car to the dyno because it won't run at low RPM; that's no street engine in my book. Secondly, you also had to run race gas; again, hardly a street engine. Combine the two, and no one would even remotely consider that a street engine.

On the other hand, here's what I consider a 'real' street engine while outputting 1.85 chp per cubic inch:

http://www.moparmusclemagazine.com/t...340/index.html

That's right, 91-octane, 800 RPM idle, outputting 602 chp at 7000 RPM. All from a 'lowly' 340 ci 2v Mopar. At 4200 PRM, that carbureted 2v engine is putting out more hp than a stock GT at 6500 RPM.

And it's all done on pump-gas!

Apparently, your 4v, fuel-injected, non-streetable 928 bag-of-tricks come up a little short compared to 2v carbureted street Mopars.

I really don't understand it though. You have those sexy DOHC 4v heads to work with, and those Mopar guys with their ancient OHV 2v engines are doing much much better with comparitively less to work with...

I appreciate the offer, but my original cometic gaskets are holding up just fine, thank you!

What I really appreciate though is the ability to run 560-ish rwhp on 93-octane, all the while behaving like stock at idle and cruise.

Let's see, what does 560 rwhp at 5.0L come out to be?

560 / .85 = 659 crank hp

659 chp / 5.0L = 132 hp / Liter

659 chp / 302 ci = 2.18 hp / cubic inch

HOLY CRAP one must admit that those number are beautiful, aren't they?

And the most beautiful thing of all, at a mere fraction of the cost compared to ANY other package at that power level, is FULLY STREETABLE, and can even pass emissions.

WAIT A SECOND, I made a BIG MISTAKE! There are no other packages available putting out that kind of horsepower for a 32v 928, street or otherwise.

My sincere apologies...

Fastest928

One kety factor for making HP is rpm based. If you can create torque at higher rpm, then you can generate more hp. The long standing "holy grail" of engine-eering is 100 bhp at 6000 rpm. Why? Becuase, standard materials and manufacturing processes can make the components. When you raise the rpm to 7000, you now need lwt components, or 8000, you need even lighter weight components.

But a MC engine spins 11,000, if you can make a mere 75 ft/lbs of torque, you make 150 hp!

So, small displacement, multi cylinder engine have smaller parts thatweight less and cxan spin at higher rpms...

Plus, MC engine have state of the art air flow technology ... there is alot ot learn there.

We have been dyno'ing quite a few GT3 recently, all making about 340 - 360 rwhp out of 3.6 l. Funny thing is that they are rated at 380 chp! Short stroke, bog bore, lwt components for a 7400 rpm peak!

The RACING versions dyno at close to 400 rwhp! Same engiene size!

Marc

the flyin' scotsman

Thanks Marc...........if I understand your response correctly the reciprocating internal engine mass is the reason for horsepower limitations and replacing components with light weight versions may indeed increase horsepower @ higher rpm and with the resultant loss of reliability and torque.

I totally agree that air flow has come along way with pressurized air boxes etc and free flowing exhaust systems all with the respective emmisions controls in place. Gotta wonder how the air systems would be designed today if the 928 was to be remanufactured.

mark kibort

I dont ever like to speak for Marc, but i think the lightweight and strong componets are only part of the equation. they need to flow at the high rpms too.

those GT3 cup cars that Marc are dynoing are running 350hp to the rear wheels out of a 3.6 liter. this is still a factory race engine that can rev to over 8000rpm. the upgraded engine, (still not using individual throttle bodies) can make more than 400hp at the rears. the ALMS engine , with the individual throttle bodies, makes more like 440hp. (even though that is its spec flywheel rating!)

again, forget about thinking of engine torque, as a number. its about hp. with hp, gets the torque through the gears for the acceleration. (unless you are talking about a street car "driveability".) Now, reliability! yes, this the major factor. with the Cup cars, ive heard they are bullet proof, but the GT3RS with the high output engines, are rebuilt several times a season! (and are very fickle/ expensive!)

I still remember a MG that was running ALMS and using a 5 liter l it was a true race engine. the owner said, 500hp flywheel. it was the best of everything and had the throttle bodies with the motorized slide etc. trick stuff, 13:1 compression. if you look at the top ALMS V8s in the prototype class, or the old Panos, i think 600hp was the norm. (flywheel) however, with downforce, restrictors, and weights in the 1700lb range. the days of the 1000hp monsters are gone, and now its about dependability/reliability/life and the chassis.

mk

mark kibort

and thats the logic that makes the PCA racing for a 928 unfair. Look at what it takes for a 944turbo to make 350rear wheel hp. (the S4 with a ton of work, barely makes this)

the 928 5 liter with some major mods is the same as a 951 with some mods too. BUT, the 951 has a distinct weight advantage. Remember i always talk about the package. absolute weight is 2/3s the fight vs just HP to weight. a 944 will always be able to get lower in weight, ESPECALLY with a turbo.

So, there is no reason a 928 couldnt race in GT3, as it should by ALL and ANY reasonalble logic. go back to basics for a moment, barring any losses, 1 bar of boost makes a 2.6liter a 5.2 liter effectively, RIGHT???? Most racers can over come those losses and make the effective output, without MUCH of the cost of what it would take to make a 5 liter 928 engine have the same output. there are guys on ever 944 street corner with turbos with 360 rear wheel hp. the hightest 5 liter we have EVER seen on a 928 is 353 by Devek.(so far)

And, of course, a 3.0 liter turbo as it fits in PCA is GT1, as it should. 1 bar of boost makes it effectively at least a 6 liter 928 engine, and thats just at 1bar.

dont forget, turbos, for one of their advantages, make similar hp gains without MUCH of the engine weight, and thats the main point here.

the 928 to be classed correctly should be in GT3. even still, it would get smoked!! (based on times so far, PCA GT3 class top drivers run as fast as Mark anderson in his 6.5 liter 600hp monster!!!!!) (and the GT4 are not that far behind!


MK

Jim bailey - 928 International

The 911s racing in POC and PCA are fast largely due to cubic dollars being spent and the availability of RACING parts. The nice GT3 racing headers and exhaust cost about $10,000 a set. The classification of cars by HP to weight only makes sense for drag racing! But I do not expect POC or PCA to change any rules to favor anything other than a "911". They are serving the vast majority of their "customers " just fine.