Aero drag being a huge variable it is, it would be great to know the frontal area of a 993 in all forms of bodywork. Wings, splitters sideskirts etc. Ride height would play a role as well.

 

K24

The RPM drops for the 993 GT2 stock gearbox vs. stock are approximately as follows:

1st. 2600 RPMs vs. 3,100RPM drop in stock
2nd. 2,000 RPMs vs. same
3rd. 1,000 RPMs vs. about 1,400RPMs drop

1st gear of GT2 will give you about 9mph more at 6800RPMs (48mph vs. about 39mph stock).
Chris, the Paul Frere book has some info on aerodynamics, let me know what you need and I can try to get it for you.

 

Jean,

Thanks for the info. I always found this RPM drop to be very anoying. Unless I really wring to redline it out I am outside of the powerband when I shift into second. I am sure my larger turbos play a role in this.

 

Guys,

Thanks for all of the input (pun intended). I have elected to use the GT2 gear sets for 1st and 2nd gears. If you wind the motor to 6,500 RPM's the old RPM drop was 3,000 RPMs. On the new GT2 gears its 2,500 RPMs. This will allow me to load the turbos more in first and be in a sweeter portion of the power band after the shift into 2nd. The 2nd to 3rd shift only changed by approx 100 RPMs.

Jean your numbers are a little different because I used 6,500 as the shift point. The RPM drop gets bigger the more you rev the motor. You must have used 6,750 as a shift point. I try to shift before that.

If anyone wants the excell spread sheet that I used just e-mail me and I would be happy to provide it to you.

Tom