Diff ratio for 400+WHP!
 

Hi all,
I currently have the stock Stillen SC setup making 380WHP with a 4.08 diff. I am about to get TopgunZ A to A kit and the 2.8" SC pulley and have it all retuned. Is the 4.08 diff going to bit a bit low for this sort of power and therfore should I replace the 4.08 with a higher ratio or go all the way back to the stock ratio diff gearing? :driving:
Regards.

Given that some guys are running with 4.36 gears, I'd stay with the 4.08's for now and see how you like them post-tune. You can always dial back the throttle map a bit if it's too twitchy.

WOW 4.36!!! OK and thanks for that. :tiphat:

+1 i would stay with the 4.08 so you can get the acceleration off the line

Depends on if you're getting traction in second and third. If it hooks up, you're fine. If all it does is blow the tires off, swap back to the stock gears.

Who in the world is doing 4.36 gears on a boosted car!? I personally am considering switching from 3.69 to 3.3!

Personally I would leave them. You can always buy stickier tires if traction is an issue with 4.08 gearing :inoutroflpuke:

I think he meant 3.36 which is the FD of a 7AT. Personally I think that 4.08 on a boosted car is a bit of a stretch and the car should be making more torque on the dyno with 4.08's over what an OEM 6MT 3.69 makes seeing as the gearing is a torque multiplier. Unless the tuner compensated for the gearing during the tune.
FWIW I did a pumpkin swap on my 7AT G37 and going from 3.36 to 3.69 was the only mod that I've ever done outside of boosting my Z that you can feel instantly. The Pro: Immediate and significant acceleration, Con: Loss of cruise control (meh ) top end decrease in trap speed.

you need some MT 305 35 18 Drag radials set to 25 psig
no traction problems at all