Undutched

Dear all,

I am writing in this forum, although I have a 964 and this forum seems more lively in regards to mods.

http://www.turbos.bwauto.com/afterma...bot/index.html

The calculation Im using:
Link to BW Matchbot

I have a 964, soon to be turbo (twinplug) and need some figures to look for proper turbo size. The engine will have a GT3 4.0 crank and will be running Gt2 cams and ported heads to go along.
I am unaware of accurate Volumetric Efficiency and BSFC numbers of air-cooled turbos. Should VE be lower, around 90-95? With the BSFC I simply do not know what to add for air-cooled variant.

Question is either GTX35/EFR 8374 or GTX40/EFR 9180. It seems right in between and I'd like some certainty before going either route.

TT Surgeon

Ck out Pelican, a lot of hi hp twin plug builds over there.
C

Undutched

If anyone cares I search around a bit:

numbers were around here:

BSFC at 6,000RPM .52 at 7,000RPM .60
VE max at 85%

DiegoR

Also, what's your RPM limit and power goal? Selecting the proper size turbo sometimes is a major task for the ultimate response and power balance.

Undutched

Power goal: 650-750HP. Engine can rev to 8,000. But that is part of the problem. I doubt most turbos will be able to cope or they will be too large.

DiegoR

How about the BW EFR series? The B2 Comp Cover B 76mm should do the trick and plenty more to get.


No afiliation:

Tacet-Conundrum

Didnt the 964 have a single Turbo - and didnt Porsche put the a small number of single turbos from the 964 into the 993 around 94? Some people have claimed this but I don't know if it is true or not? Don't know if the motor was the 3.3L or 3.6L since I'm not too familiar with the 964 series of cars.