clubsport1

BillV, cup cars are M001.

Bill Verburg

Danka!

Bill Verburg

More RSR intake

clubsport1

I checked with the owner of the genuine RSR, he was kind enough to send me pictures of the intake systems and the original is the same as the intake plenum that BillV posted in his pictures. I also had confirmation that the factory RSR never came with varioram.........as we knew

Peter R.

Right, I've dropped the ball completely now.

Red9 says his RSR is a vario.

The pics posted here (by Bill and verified by Clubsport 1) show no vario.

Can anyone comment on the valvetrain used ? It would seem my original comment on the RSR's being non-vario holds water at least in the induction argument. Can anyone verify my mechanical lifter comment ?

Thx,

Peter R.

clubsport1

Cuppies and RSR have different cams to RS and mechanical lifters.

NP993

It wouldn't make sense for a race car to have varioram. Varioram is street-car technology; its purpose is to create a broad torque curve and enhance driving enjoyment throughout the RPM range. Race cars don't need broad torque curves. They need a lot of power in a narrow high-RPM range, which varioram has nothing to do with.

Bill Verburg

Cups used 964 style adjustable rockers

Forged RSR rocker, adjustment by shim


Stock 993 hydraulic


993 modified to mechanical


Assembled RSR adjustment by shim

NineMeister

I think it is clear now that the 993RS had the large port varioram system fitted as standard, whereas the 993RSR engine had an individual throttle body twin plenum intake system.
Louis, assuming that you have been offered a 993RS varioram intake, the answer to your question is that although the RS manifold has larger ports and has the capacity to flow more air, unless the engine has been suitably modified to require this additional air you will not get more power that you could get from the standard varioram system that you already have, indeed you may even lose torque as a result of the larger diameter runners of the RS system.

In my opinion Porsche got it wrong when they specified the the intake port diameter of the RS and RSR engines, going way too large for the power levels they achieved. As a result the air velocity suffers, hence why they spent a lot of time designing and making variable length runners and large resonance controlled plenums in an effort to band-aid the actual cause of the problem. The RS heads have bucket of an intake port at 46mm diameter so the RS varioram is made to match this size. Similarly the RSR manifolds have approximately 50mm diameter runners with tapered throttle bodies bolted to the heads which reduce the diameter from 50mm down to the 47mm of the port which is way too big for the 3.8 engine, hence why they struggled to make a lot more than 100hp per litre.

For your 3.6 engine, the optimum is to carefully port your existing varioram runners to a constant taper from the throat down, then continue the taper through the bore of the injector stack (I turn them on a lathe) to match the head. We do this on all engines fitted with the 9m heads, in tests it made around 5-10hp against a completely stock assembly.

Peter R.

So now all that needs to be cleared up for me is that the 3.8 in the RSR indeed uses the same base engine than the 3.8 that was offered as a factory option from 94 to 95 with 285 bhp.

Thanks everyone,

Peter R.

Wilder

Great info from everyone.

Bill: thanks for the awesome pictorial and tech info.

Colin: thanks so much for your very clear response. It gives my a very good idea of where to go now. I only wish you were on this side of the pond. I'm itching to drive a 9M car.

Bill Verburg

Not quite.
The normal 3.6 & 3.8RS(M002 or M003) are street engines, the RSR is a race engine, there are numerous detail and spec differences. The Cup splits the difference

clubsport1

I don't think you want the RSR engine, as it is a race engine,,,engine refreshes are required after "working hours" rather than the 10's of thousands of miles we expect from our road engines.