Diff ratio for 400+WHP!

Optimiser · 10-31-2016, 10:07 PM

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?

Regards.

ban25 · 11-01-2016, 12:57 AM

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.

Optimiser · 11-01-2016, 01:41 AM

WOW 4.36!!! OK and thanks for that.

chuckie311 · 11-01-2016, 10:16 AM

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

Chuck33079 · 11-01-2016, 10:22 AM

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.

tonyHTX · 11-01-2016, 10:35 AM

Quote:

Originally Posted by ban25

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.

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

jmroy6 · 11-01-2016, 11:02 AM

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

solidus · 11-01-2016, 03:36 PM

Quote:

Originally Posted by tonyHTX

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

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.

Z eliminator · 11-04-2016, 05:21 PM

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

10-31-2016, 10:07 PM	#1 (permalink)
Optimiser Enthusiast Member Join Date: Mar 2013 Location: Australia Posts: 455 Drives: 2012 Nissan 370Z MT Rep Power: 20144	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? Regards. wideglideleon likes this.

11-01-2016, 12:57 AM	#2 (permalink)
ban25 Enthusiast Member Join Date: Nov 2009 Location: SF, CA Posts: 339 Drives: 17 C7 Z06 M7 Rep Power: 66	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. __________________ 2017 Corvette Z06 7MT \| 1LE \| Stage 3 \| DSCSport

11-01-2016, 01:41 AM	#3 (permalink)
Optimiser Enthusiast Member Join Date: Mar 2013 Location: Australia Posts: 455 Drives: 2012 Nissan 370Z MT Rep Power: 20144	WOW 4.36!!! OK and thanks for that. ban25 likes this.

11-01-2016, 10:16 AM	#4 (permalink)
chuckie311 Enthusiast Member Join Date: Jul 2012 Location: las vegas Posts: 313 Drives: Q50/G37 Rep Power: 13	+1 i would stay with the 4.08 so you can get the acceleration off the line __________________ Tuned by (Seb@Specialty-Z) 2011 G37 Cam'd FBO 347whp 280wtq Corn Fed 4.08 Gears

11-01-2016, 10:22 AM	#5 (permalink)
Chuck33079 A True Z Fanatic Join Date: Nov 2011 Location: Houston Posts: 12,265 Drives: 2011 370ztt Rep Power: 29539	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. __________________ 2011 MB Touring-Sport-6sp-Nav/GTM TT/FI TT TDX/JTran/Kosmic/Eibach/Hotchkis/SPC/CSF/RPS/SoThatsWhereAllMyMoneyWent

11-01-2016, 11:02 AM	#7 (permalink)
jmroy6 Base Member Join Date: Sep 2015 Location: CT Posts: 179 Drives: Spirited Rep Power: 235	Personally I would leave them. You can always buy stickier tires if traction is an issue with 4.08 gearing __________________ 2012 370z GTM SC

11-04-2016, 05:21 PM	#9 (permalink)
Z eliminator A True Z Fanatic Join Date: Jul 2009 Location: Ontario Canada Posts: 1,659 Drives: 370 Z 7AT Sports Rep Power: 19	you need some MT 305 35 18 Drag radials set to 25 psig no traction problems at all __________________ 12.343 @114.14 . 4.5 stroker motor is now being built. Dec 1 2015.

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