Join Date: Apr 2003
Location: Terre Haute, IN
I've since decided against it, but here's my thoughts. One of the biggest downsides of the 930 is off boost throttle response. Combinations of gearing, compression, cams and intake tract. The ITB's may contribute little to the max horsepower numbers but I think it would help driveability and response. That was my intention with my first build recipe of 8:1 TT ITB EFI 964 cam'd engine behind a 915. It wasn't for the biggest numbers but for response an flat torque.
The guys on Rennlist stayed consistant with the ITB's being best but difficult to keep in tune for street use on turbo application. I think it's a combination of ITB's always being more intricate than a single TB and the difficulty simply GETTING TO THEM with all the turbo plumbing and IC. I will not be able to tell you the answer since I've since divided my parts amongst two engines and will keep the ITB's for a NA car. Going the proven Carrera intake on boost.....I whimped out and decided to follow the heard.
Most all out race cars still run a form of ITB's even under boost if rules allow.
72 RS spirit 2.7mfi, 73 3.2 Hotrod on steelies, 76 993 3.3efi TT, 86 trackrat, 91 C4s widebody,02 OLA winning 6GT2, 07 997TT, 70 914 v8