help with diff ratio's for 1/4mile

[fixeruperer]

hey fellaz,

i have 4.11:1 in my g series now, and i thought it was great until i hit the strip. 1st gear is way to short i dont make any power to 45-5000rpm my limiter is at 7900rpm (will have it retuned to 8500 soon) so i dont get much room to play with and when i spool it up and lift off the clutch i have to straight a way go for 2nd and thats to much lost time..
im thinking of maybe running 3.5 or 3.7:1 but im not shaw how much differance it will make, i was going to try a start in 2nd to see what happends.
i love the ratio as it is but i cant launch this thing at all, do you think the differant ratios will do what im wanting ?

thanx.

[87lux]

You might need to post up a little more info on your car's setup. It sounds as if the turbos is a reasonable size. Are you spinning off the line? What tyres are you running? Also how is the car at the end, are you having to shift just before the line or are you just topping out past it.

[fixeruperer]

yeh the wheels spin in a huff (with antilag, without antilag they dont but ive never tryed not using antilag at the drags).
the tyres are kumho ku36's with massive burnout.
with the shit start im topping 4th nearly have to change to 5th, with a good start im going to have to shift for 5 i think.

im thinking now that maybe the lower ratio will help the start but kill every where else , im just going to have to smash 2nd as fast as i can, i couldnt before due to synchros but hopefully i get the box back by next week and i can try again..

[pandaah]

3.9 ratios are a good drag diff... give one a go, only you can tell how good it will be unless you describe exactly the way you drive and every exact detail of your car...

[87lux]

Well it sounds by what you said that changing to a taller ratio like a 3.9 or 3.7 may be benificial. Another option would be running a taller tyre for the drags which will give a similar result although it won't be as dramatic and that way you can keep the 4.11's for the street if that's what you're after.

[fixeruperer]

yeh exactly, but the main question was that if from 4.1 to 3.5 or 3.7 would i get the extra legs im looking for on the launch, because i havent done much in ratio changing that i dont know how much differance to expect.

thanx 87lux, i dont have any room for bigger tyres, im just going to have to try differant things.

[pandaah]

3.5 would definetly give you the extra legs for the take off, but do you think you have the power to keep the acceleration rate the same?....

how much HP are you running and boost.. outta curiousity

[87lux]

Yeah the only problem is you don't wanna go too tall otherwise it may do the opposite and bog down too much. I've got the opposite problem to you with my ma70 but in the end it really depends on you're car's setup. My issue is i'm having to shift into 4th just before the line I'm only doing 110mph and i'm running 3.7 diff gears it did a 2.0 60ft. I've got a 4.3 sitting here i'm gonna try and it should at least make more use out of 4th. I have had my 1j lux out as well and it had 4.3 gears and the exact same size tyres and it ran a 2.0 60ft which is the same i got out of the soup. It's all trial and error i suppose

[fixeruperer]

i dont know, im going to have to find out, that can be my last resort.
315hp@18psi on 1120kg.
gettin a retune soon with more boost and rpm.

[pandaah]

lol im sure youll be fine with a taller diff.... youd probly try to experiment with the 3.5 3.7 see which one does you the best justice, but with a set of slicks, antilag, a good launch, taller diff and soft rear suspension im sure youll rip thru the quarter

[fixeruperer]

what box are you running 87lux, im using a w58 through the 4.1 g series, 16's with 45's and im crossing the line at 109.7mph but near limiter in 4th.

[fixeruperer]

thanx pandaah, i hope so hey haha.
ill let you guys know what happends, but ill try the new box first.

[87lux]

R154 with 265/35r18's although i have also used 255/40r17's. The ma70 1j's got about 340hp and has done 12.9 so far and would weight approx 1500kg. Do you know what your 60ft time is .

[fixeruperer]

60ft was a snail paced 2.6 haha.
launch was crap rev limit first crunched 2nd a few times, found second then i had to wait for spool up and i mean w-a-i-t .

[87lux]

Well from the sounds of that you need to go out a few more times first. If you're gonna change your rev limit you'd be able to hold 4th for longer too. How many times have you been out and how many passes have you done. It took ages for me to get around finding the right revs to launch. I ended up taking off from 4000 upwards with lots of clutch slip to reduce wheel spin. Normal street tyres won't hook up as good as street slicks which is another option you could take.