chip_962

Does anyone know why the factory microfiche calls for a unique intake manifold part number on the Carrera RS M64.20 engine...when it really seems the same as the stock 1997 993? There is a venturi tube and vent tube which is also different on the fiche. I know that the runners L&R are different...and it seems logical that the main manifold would be different...but I cannot find anyone who can point out a difference in the RS manifold (main section) which warrants the different part #.

Joe@Fabspeed

The 993RS Varioram had different part#s for the top section of the varioram and the bottom intake tubes for 2 reasons.
1st the top section of the 3.8RS Varioram had different vacuum connections for the hydroboost vacuum accumulator as is also used on the 3.8L Supercup 993s. This resulted in a different part# and placement of bosses and parts were different. The top section flows a little better than 993 3.6L varioram too.
The 993RS bottom intake runners/tubes are larger diameter and made of Magnesium for extra lightweight.......versus the 993 3.6L varioram tubes that are aluminum. Once again these reasons had Porsche to have separate part#s.

Have a great day!
Joe @ Fabspeed Motorsport USA

gristle101

Would this lighter/better flowing intake yield a performance upgrade when applied to a 3.6 engine?

nine9six

Warning...Not an expert level response!

Maybe not by itself, but in conjunction with other free flowing mods...set of headers, RS cams, hi comp pistons, multi-angled valves, and flowed heads; you might have something there.

But after all that, why not install a supercharged, turbo flux capacitor?

FLYT993

love seeing our cars on the cover of magazines...

Steve Weiner-Rennsport Systems

Good question!

The answer is; Yes,......but not a factory street intake system and several other things need to be changed as well to realize all the potential.

A few years ago, we did a 3.6 for a client (964) changing only the intake system, exhaust system and adding RS cams (which are very mild). HP went from 247 BHP to 335+ BHP. Everything else remained stock. Visually, it wouldn't pass smog, but the exhaust emissions were as clean as original.

It just comes down to budget.

race911

Yet the 3.8 I ended up with is 20 short of that, and if I remember the on-again-off-again Varioram Kim tried.........it wasn't even worth the bother.

(Yeah, yeah, put a real intake on the thing.)

doc_porsche

that's a nice bump in bhp. but for $20K +, that's pretty hefty

NineMeister

The answer to the OP question must be based on the holistic design and tune of the engine. In my opinion, firmly based on my own findings from engines we have built and run on the 9m Dyno, The RS manifold with its larger diameter (46mm) runners works best with the RS engine with its large diameter (46mm) intake ports, whereas the stock 993VR intake with its smaller (43mm) runners works best with the stock 993 heads with its matching relatively small (43mm) intake ports. We have also tried both on the 9m Billet heads and found that the stock 993VR manifold works best, which is probably no surprise since the Billet heads have and intake port with an entrance diameter of 42.5mm.

The nearest comparison that I have on file are these dyno plots, showing the difference between a stock 993nVr, a genuine 993RS (remapped) and a 9m 993+3 which is also a 3.75 litre with billet heads, ported VR runners, 9m Sport cams and 100 cell cats.

Please make your own mind up if this is a reasonable deduction.