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Power & Torque for a 3.8 RSR

Dave Wilkinson

Dave Wilkinson

New member
I'm trying to collate some factual information to go onto a new 964 web site (www.964uk.com if you are interested) and I've come up with a small anomoly which I'd like to resolve. According to Adrian Streather's book, the 3.8 normally aspirated engine developed 300 PS but the figure he has for the torque is 488Nm (or 360 ft-lbs) at 5250rpm. Is this right?? Considering the maximum torque produced by the 3.6 Turbo engine was "only" 490Nm this seems an astonishing figure for the normally aspirated engine.

Could someone "in the know" please confirm or deny these figures for me??

Regards

Dave
 
I very much doubt that 360 ft/lb is right Dave, I'm sure the figures I've seen for it elsewhere were about 280ish.

For referance, back in may when I went with the Turbo boys for a dyno mine (964 C2 3.8) produced 323bhp and 300 ft/lbs
 
Thanks for the responses guys. I think the "swapped units" theory sounds pretty plausible and 355Nm sounds about right judging by the other figures. If anyone can point me to any authoratative web site where the actual figures are published I would very much appreciate it. Whilst the theories are completely believable I'm not keen to put them in a public web site without some data to back them up.

Regards

Dave
 
I had a 3.8 engine in an X51 993C2 (blueprined and 964 not 993), I know for a fact that was 285 BHP (same as Varioram 3.6 when it arrived), but torque was higher --- same as 993RS I seem to recall.
 
With a bit of Internet research Steve (madmoog) and I have concluded that it's 300 PS and 360Nm and I have changed the figures on the web site to reflect that.

Regards

Dave
 
993 RS engine is different in that it has varioram...I believe this improves the torque slightly to 260 ft/lb (factory figure)

In the heading here it mentions 3.8 RSR....I was under the impression that the RSR 3.8 engine in the 964 was good for 340 bhp?

The RSR is different car and engine to the RS 3.8, which I understand was 300bhp from the factory.
 
only figures i could find were for the RSR model which were, Paul Frere quotes 340 hp and Uli Upietz quotes 325 hp @ 6900 and 360nm @ 5500.
 
looking deeper frere also quotes for the 3.8 rs 964 as 300ps @ 6500 and 360 nm @ 5250. He also quotes RSR's without restrictors in thier intakes at 375 hp le mans spec being 360hp with 48mm restrictor and 355hp with 39mm resttrictor. (all quoted from the excellent 911 Story)
 
Laurence,,,,the extra outputs you quoted above 340 for the RSR sound like 993 RSR values, obviously there may well have been cross over towards the end of the 964 's life are you sure on the dates?

Quite sure for 964, regular 3.8 RS = 300 & regular RSR = 340,

These were the outputs as the cars were sold and probably homologated what tuners or factory race teams did after that could well be another story.
 
Paul the quotes are for the 3.8 964 RSR and the 3.8 964 RS . Pages 302 to 308 of the 911 story cover the development of those cars specifically. Page 308 onwards then goes onto cover the 993 RS in all it's guises. (911 story Seventh edition! it's also in the sixth edition too but not sure the page numbering is the same)
From the book "Take the example of the Porsche 3.8RSR , the unrestricted engine pf which develops 375ps . With the 48mm intake air restrictors required by the 1993 le mans regulation, the power drops to 360ps."
 
interestingly Frere quotes the "RSR" version of the 993 engine at 340ps . Just a thought but the main difference would be the intake system, varioram for the 993 and individual throttles for the 964 ?![8D]
 
Not sure about that Laurence.... varioram on 993RS, but not on 993 cup or RSR....sounds like they needed a better proof reader.

Here is a pic of a standard factory 993 RSR which was rated at 360bhp........note it does not have varioram in the real world, only in the written word!



5C9677F639144CCD8EFBD76E3382837D.jpg
 
actually the book did'nt say varioram , that was my mistake. from the book again under the heading The 911 cup 3.8 RSR (993 for clarity) "m64/80 engine which operates with an 11.5:1 compression ratio is a development of the engine which powered the 964 series Carrera RSR . It features a reasonance intake system electronically controlled by a flap valve , and six seperate throttles located near the cylinder heads, a system ensuring immediate throttle response."
 
Development of 964 RSR lump......360bhp vs the 340 of the 964RSR.....I have been told this by a chap who used to look after these cars in race teams when they were new, who clearly knows more about them than us!

I wouldn't be suprised if there are late 964RSR running the developed engine though.......both race engines though, so not the engine lifes we require.
 
Laurence, the figures you quote are correct as far as i'm concearned. The problem is that there were 3 different restrictors for the different race series around the world. In addition to this there were 3 different exhaust systems ranging from a system with cats, silencers and heat exchangers to a straight out system with 3 into 1 spaghetti headers and then straight out pipes.

I'm not sure which exact setup gave which figures quoted above except to say that the 964 RSR engine with no restrictors and straight out exhaust will give 375bhp. I have one in this spec and it sounds great.

I suppose the 340bhp is for the car with full exhaust, etc. The rest provide the in between figures of 355bhp and 360bhp.
 
My engine (rebuilt by RS Tuning) has the following specs:
Max torque 393nm @ 6200 rpms (btw > 360nm between 4500 and 7000 rpms)
Max power 269kw @ 7020 rpms
 
How can you write a new book using facts from other books,only use factory facts to make a accurate book.Good effort to do a book,wish i could finish mine off!
The 993 engine series for a cup engine is a 64/70 series and the rsr is a 64/ 75 or a 64/80.The 964 and 993 engine look very similar but in the detail are very differant,ie crank,rods,pistons,ecu etc
The 964 run from 340 to 375 ish,so did the 993.
I can dig out the factory torque figs if you want them for both cars from the factory brochures /sales info.
My 993rsr engine was 378 bhp and 405nm.

 
Just for clarity . I quoted the only 993 in the book to be designated RSR, the one for the Japanese market and hence the engine code! I was mindfull that someone might say that there was never a 993 RSR made ! With regards to Paul Frere's book i personally would view it as second only to the factory data . Which can be few and far between. Certainly Mr Frere was around and visiting Porsche when these cars were made and was given special privilege to drive them whilst they were being developed. Can't get your ear much closer to the ground than that!
 
Paul Frere books are good ,but you do get the odd wrong info which is probably down to the typos and proof readers etc
They did make 993 rsr for sure,so far i have come up with 22 cars,2 are in the uk that i know of.
The engine case and most of the bottom end is 993 rather than 964,even though the case numbers are still 964.
 
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