gear ratios

[compactfean]

K so ive seiarched for days. Anyone Improve there quarter mile time by changing rear end gears and what is your setup...please don't respond giving explanations I know the benefits and disadvantages if high and low gears. Just Trying to get hard data here. Not opinions

[kentuckyslider]

How much power are you making, what times are you runnin, and what r u revving to?? I ran 2 diffs with my SR. A 3.91 j30 and a 4.36 skyline diff. Trap faster with the 3.91 and run quicker et's with 4.36. I revved to 7800rpm and made between 345whp with one setup and 411 with the other.

[compactfean]

Haven't taken it to the track yet. Ive got my ecu tuned for 8500 rpm but usually shift at 8000 Ishmael. I'm running 1.3 bar with 272 cams and bored. Over. It sounds like for my setup the skyline diff would be good.

[kentuckyslider]

With the 4.36 diff and 26" slicks(235/60/15 and 255/50/16 DR's both 26") our cars will do 107 in 3rd and 140 in 4th at 8000rpm. Unless you are making over 600whp then the 4.36 is the perfect gear for the SR. From my experience if you are running a really big turbo(35r or larger) on a SR the 3.91 is a better option. The taller gear puts more load on the engine and tends to make it spool faster and stay in boost longer in each gear.

[pauliedrft]

So would bigger include t3t4 .63 50 trim ???Stage 3

[codyace]

4.36 (skyline diff) would be perfect for any street or drag car out there, regardless of turbo or power.

I usually suggest 4.60 Final DRive for guys for road course guys like me, as it helps get rid of the often annoying 2nd vs. 3rd gear spots on some tracks.

With 265/35/18's and the 4.60 final drive my car will do 129 of the limiter in 4th gear, via GPS. That's damn near perfect for how I have the car setup. I don't mind putting it into 5th on some tracks

[pauliedrft]

meaning the ring gear am i correct .see i have the 408 240 ring set in my car now and well first gear is pointless i just wandering if i can use j30 393 ring and pinion set in my 240 pumkin or should i just leave it alone and stay 408 . thanks for helping

[kentuckyslider]

If you want to use 1st gear in a 2600lb rwd car with this kind of power you need to run MT ET drag radials all the time. (which will kill 2nd gear in your transmission much quicker, trust me) I would do the 4.36 diff or leave it alone. The 4.36 were found in the RB20 powered skyline hrc's and the 180sx with the ca18's.

[codyace]

You usually find them on ebay for 300ish bucks all the time...really good deal if you ask me.

And I would never mess around with a 3.9x from the J30...with our transmisison rations, that would be very boring.

If ayone wants a 4.6 let me know. I may be able to secure a set.

i

If you want to use 1st gear in a 2600lb rwd car with this kind of power you need to run MT ET drag radials all the time. (which will kill 2nd gear in your transmission much quicker, trust me) I would do the 4.36 diff or leave it alone. The 4.36 were found in the RB20 powered skyline hrc's and the 180sx with the ca18's.