Diff ratios

I have an 86.5 N/A supra. Recently i had the 1jzgte engine installed with the supra turbo gearbox. Changing the gearbox has changed the gear ratio to slightly taller than it was originally. At 240km/h(150Mp/h) the car is almost at 6000rpm. It seams to still have plenty of go left in it at that speed. The engine redlines at 7000rpm which suggests to me that the gear ratio is a bit high for quarter mile drags. Only been once pulling high 13's. Was wonderin if anyone knew the standard diff ratio of an N/A 86.5 supra and if they can be changed without too much hassle.

[suprra_girl]

lol
yup you hit the nail on the head
your diff is a 4.3 from memory and the 87-88's use a 3.9 lsd and 89-92 use 3.7's
find a diff from a manual 7mgte or 1jzgte and she should pop right in
should help you out anyhow

In that case i would have thought i'd need the diff i have in it. I want a lower top speed not higher. Also i'm not 100 percent but my car seems to have an LSD diff?

[suprra_girl]

i'm not sure what diff you have... have a look at the id tag in your engine bay should read either G254, G255, G313, G314, G315, you get the idea
even numbers are open diff
odd numbers are lsd
let me know what one you have...
well you're in a catch 22 then...
you want lower speed so you need a higher ratio diff
but you don't want as high gearing so you need a lower ratio diff..
i think you need to make a sacrifice there somewhere hehe

G285? Sorry my understanding was the higher the diff ratio, the lower the top speed. Is this not correct?

[suprra_girl]

i'm not sure what diff you have... have a look at the id tag in your engine bay should read either G254, G255, G313, G314, G315, you get the idea
even numbers are open diff
odd numbers are lsd
let me know what one you have...
well you're in a catch 22 then...

but you don't want as high gearing so you need a lower ratio diff..
i think you need to make a sacrifice there somewhere hehe

yes you are correct but you were also saying that your rpms were too high?

[suprra_girl]

and yes it's a 4.3 4 pinion lsd

I don't think my rpm is too high. i think it's too low for the speed i'm doing. It used to be higher before i changed the gearbox. It definatley says W58 then G285.

[suprra_girl]

ahhh
are you using the stock gearbox?
you should really use a R154 if you're doing drag racing... w58's aren't known for holding up to high hp :P

here is a link for all manual gearboxes and their ratios if it helps
http://www.geocities.com/MotorCity/Pit/997.../Gearboxes.html

Cheers, you rock! just wanna keep playing with it and hopefully get under 13sec one day. dunno much about the 1jz's. had the 7MGE then the 7MGTE, so i'm kinda new to this engine. Is the R154 the same ratio as the W58?