A.Wayne

The prototype engine in the GTP was the precursor to the 944S . 924GTR's had the 924 engine . Ottenger made a 16V head for the 924 engine that was available in the early 80's. very rare and never raced to TMK..

Chris White

420 crank Hp is around 350-370rwhp. Good but not great output for a 2.5 – especially since it runs up to 7500 rpm. The fact that it would do that for 24 hours is a whole different issue – that is not easy!

toddk911

A. Was the GTP and GTR no difference in motors?

B. 16v mod to the 2.5 vs. staying 8v and going 3L ?

Of couse 16v AND 3L is would be the best.

Yea, 6.8:1 would NOT be a street car. lol

Found this:

http://www.bigporsche.com/944gtp.htm

http://www.bigporsche.com/944gtr.htm

So Wayne, the GTP is the 944 engine and the GTR was a 924 engine. Wasn't the 924 only 2L? Making that 420hp even more imprerssive.

333pg333

1981 Porsche 944 GTP
This is the race car version of the 944. It raced in the 1981 24 Hours of LeMans and finished 7th overall.
The GTP was powered by the same 2.5 liter inline-4 engine in all 944 cars, turbocharged, with 420 HP

Model 944
Year 1981
Engine: Water Cooled Turbocharged Inline 4
Displacement: 2500 cc
Horsepower: 450 hp
1/4 mile: 10.4 sec
Layout: Front Engined / Rear Wheel Drive


Notice the 1/4 mile time? Not too shabby for a 1981 car!!

gt37vgt

hmm that 1/4 mile time looks like 900kg car 12" slicks to me

Duke

I wonder if that 1/4 mile time is even real.

333pg333

Yes I wondered that too. Seems an odd stat for that sort of racecar...but I'd like to believe it.
It's quicker than a Veyron....

toddk911

Well, the pwr to weight could pull a 10 sec 1/4 but it would have to be ALL top end speed as with 6.8:1 compression the 60 ft would be like 3 sec????? LOL

Duke

Not if you launch at 7000 rpm

Chris White

1/4 mile....oh sorry...they ment 1/4 kilometer....

A.Wayne

I would wager that number is @ least 100 bhp lower than they ran ...

Yes the GTR 400 + bhp from a 2L 2V engine at the time was phenomenal , especially considering it's humble beginnings. I had built a replica of the factory 924GTR with Al Holberts assistance back in the early 80's , it's been in hibernation for the last 15 yrs ... both of us now qualify for HSR so stay tuned .... LOL...

The 6.8 is only a deficit off boost , the lower compression made the engine less sensitive to detonation , which was a necessity when you consider the 1980 electronics monitoring it .

Rogue_Ant

What kind of fuel did they use?

333pg333

Sekret formula made in East Germany. There is no trace of it now nor the Krew involved in making it.

6:8.1 is still very low c/r in anyone's book. Perhaps running at LeMans for 24 hours would be the best place to have it?

Rogue_Ant

That is kind of what I'm getting at...
6.8:1 is ridiculously low. That is flat-head engine ratio. And especially considering they most likely used 100+ octane fuel in the GTP car, I see no reason to not run 10:1 CR at the boost levels they used.

333pg333

What boost levels did they use? Perhaps it was a built in safety valve to run endurance events like this?