GregBBRD

That's rear wheel, which equates to about 370 flywheel.

Since the changes were primarily swept volume with exhaust system changes, that sounds about right. The 968 valves, from almost every one of these heads that I've had on my flow bench, probably reduced the intake flow, not improved it.

Don't forget that these engines were created "pre-Sharktuner", so the tuning is probably crude, at best.

Naturally aspirated torque/horsepower is very different than supercharged/turbocharged torque/horsepower. I've ridden and driven a lot of "550 horsepower" supercharged engines....and not a single one would have a snowball's chance of beating Rob Edward's car with my new manifold on it......and it makes less than 500hp.

I believe that the "old" turbocharger factor that IMSA used was 20%. That may have changed over the years, but probably a pretty good guideline, for what is being used for aftermarket superchargers on 928 engines.

ptuomov

Would Rob Edward's car also take George Suennen's supercharged car? George did 210 mph on the road with that one, if I recall correctly. It's probably in a class that could be accurately described as a "550 horsepower supercharged engine."

Rob Edwards

Sea level, or at 5000 feet?

ptuomov

At any level, be that Himalayan avalanche level or Turkish mining shaft level.

Seriously, I've never driven or sat in or even seen live your stroker car. I do have a rough idea though how much a centrifugal supercharger makes on a S4 engine when set up properly. So I am curious if your car is going to blow the doors off George Suennen's supercharged car.

Rob Edwards

The other smartass answer is that George will win anything involving speeds over 150 mph since I am a complete wuss.


Not sure there's a meaningful serious answer to your question, George's car is an automatic with a 2.20 rear end, mine's a 5-speed with 2.73. I assume his rear tire diameter is a bit larger. Mine weighs 3505 lbs, George's is also 3500-ish. I assume we both run 91 octane 'premium'. I think we both run cats.


I can't find a fresh dyno graph on George's car any newer than from this 2008 dynopack result (below) and Bill mentions here that more recent runs on a Mustang dyno show 480 rwhp.



My dyno with Greg's intake, last October:




So I think the answer to whose doors get blown off depends on how you stage the competition. I think I'd probably take the first 1/4 mile, but George would win the next 99.75...

BTW, you have a never-expires open invitation to stop by and drive the **** out of the GTS any time you're in SoCal. Would love to get your impression!

atb

I'm not commenting on the quality of the build or the engineering design of what went into the DEVEK motors, but I did see Don Hanson's engine internals after that first stroker blew when he sheered off the oil lines on an off track excursion. I'm not an old man, but the last time I saw pistons and connecting rods that had been violated to that degree was when I saw a '64 Max Wedge drag race engine being disassembled in high school (early '80's). Grinding on piston wrist pin bosses and con rod caps... dark ages indeed.

BC

There is a lot to be said about the old days. Some of us have been around for 15 of those 20 years.

Jeez. That's a long time. Maybe I should drop everything and buy a newer car.

Strosek Ultra

What did Devek do wrong? Con rod offset, piston coating, soft rod bearings? Anything else?
Åke

ptuomov

Thanks for the inivite! Same applies to you. If you're ever close to where any of my cars is, you're automatically entitled to a test drive!

If we weren't in a debate where *everything* is questioned, including dyno charts, then here's how I'd guess which car is the faster car from a rolling start. Compute the average wheel power over all possible intervals [x, 1.5x]. Pick the one with maximum average power. Divide the maximum average power by the car's weight.

For that dyno graph of George's car, the eyeball average power for the 4200-6300 rpm range is maybe 465 rwhp. The max average power range for your car is about the same, and I am eyeballing maybe 425 rwhp. So by my rule of thumb, for the same weight, George's car would be faster from a rolling start.

Of course, if it's the case that Greg's strokers regularly blow the doors off centrifugally supercharged cars, most of them with Murf kits, then there's something wrong with my simple rule of thumb. Just haven't figured out what the problem with that rule of thumb is yet.

I think (but do not know) that Anderson's race car had a Devek stroker, and maybe Ott's street car also has one. If so, those two might know a lot more about all the problems in those terribly deficient Devek strokers.

slate blue

Why can't we start a thread of G-Tech acceleration times, G-Tech is not the only brand of course, that will give some real world "harder" numbers, it offers some level of comparison.

I can agree that tuning of these modified engines provides some real challenges, especially if you go back a decade. There doesn't seem to be a lot of quality fixes out there for this issue, its all pretty expensive. I figure that when my wife's car is done it will have cost $10K to sort. For that you get logging, 4 wheel traction control, fly by wire throttle (if you need them, multiple maps) and a very quick 2012 ECU. Yes it doesn't matter when you buy your ECU, it is when it was designed.

John Gill can offer a solution for about half that number the ECU is up to date and fast and his car runs very hard. Adaptronic seems to be a good budget choice.

For my 2 valve 5.0 litre which will be going to be finished this year and for the record it needed a rebuild after sitting for 6 years. (the coolant had caused some issues that needed attention.) I am doing some further minor mods, I believe it will run a 12 second quarter and have around 440 flywheel HP. That is going to be so much easier when I have traction control. I am putting Toyota race Conrod bearings, scraper system and larger intake valves with some nice head porting. We are flowing the heads with the intake connected and that is on a 60" bench. It's going to be interesting.

hacker-pschorr

https://rennlist.com/forums/928-foru...ng-thread.html

https://rennlist.com/forums/928-foru...a-loggers.html

TexasDude74

From the Supra world: What do a 400 horsepower Supra and a 1200 horsepower Supra have in common? They both run 12's.

Add a power glide and 5500 rpm converter and things change real quick. Ever driven a car like that on the street? I have, no fun at all.

Ptuomovs' odyssey is a prime example of the time, research and talent required to setup a forced induction system properly. If every component in a turbo system doesn't complement one another the engines are unresponsive and you lose too much time at gear changes and a far less powerful normally aspirated car will literally run away and hide.

Automatic 928's in particular are tough to drag race. Not so much due to suspension or traction issues but gearing, that 1-2 shift is brutal. Especially for a big cammed or big turbo car. There's a reason Greg builds his engines to shine in the mid range.

RET

Thanks Greg!

andy-gts

I switched from pressurized (9 psi) to the stroker as most of my driving was under 5000 rpm,,,,and the sc kicked in starting at 3000 rpm,,,,the stroker that Greg built blows my mind and every one that sits with me!!! I dont think I will ever go back with this car....

that being what it is , my gas mileage on a good day is 17 mpg on the hiway....and a turbo with same hp will be better than that for a daily driver but the stroker is not a daily driver...

123quattro

I would just expect more. My US 4.7 with Euro heads/cams and an exhaust does 272whp with the factory controller.