NEED MAJOR HELP GEARBOX AND DIFF

[318isturbo]

hi all RIGHT i have almost built my engine and i have put a skyline turbo on it YES skyline and i have been told i will be letting out over 300 bhp at the wheels.NICE
The thing is i need to put a bigger gearbox on and a diff.
i have been told that a 4.10 lsd diff will do but i will lose alot of top end

what is a good alround lsd diff for 1/4 mile and long run does anyone now
also the gearbox i was thinking does the 325is match up as they where based on the same sort of thing.

please let me no

cheers guys

[Ant]

3.91 LSD all the way, you'll need to swop the 2-5 driveshafts in or swop the output flanges from the small case unit

Turbo should be spot on the T3 unit we used on the 318iT ( malcs) makes gob loads of boost right where you want it

[Chris-W]

I've got a 3.45 lsd if you fancy a deal on it.

Cheers,
Chris

[kam-325i]

With that amount of power, would not a lower ratio do ?

Would a 4.10 just make 1st and 2nd usless ?

[Andy325i]

As mentioned above it the diff ratio depends on what gearbox (or ratio gearbox) you are using the 24valve gearboxes (M50/M52 etc) have a 2.93 ratio to compensate for the 5th gear being 1:1 (insted of fourth)

My M52 E30 still has the 4.10 diff and is mad down the bottom, but up the top end runs out of steam at about 110 (sitting on the limiter in 5th!)

Here is a useful calculator for gearing etc:

Unix nerd gearing calculator

HTH

Andy

[Templ8e30]

you'll need to swop the 2-5 driveshafts in or swop the output flanges from the small case unit

I'm not so sure about this - I put a 325i (Typ 188) diff into my 320i (same 4.1 small case unit as the iS) and it went straight in. Although the 316-320i diff is physically smaller than the 188, the distance from flange to flange (i.e overall diff width) is the same because the outputs stick out more.

I'll second that.

I have a large case 3.73 diff on my 2.7 which was originally a 320i with small case diff, it's still on the original driveshafts.

Cheers,

Iain T

[Demlotcrew]

+1 i fitted a medium case S3.25 to a 318is which has the small case 4.10.

Andrew

[Ant]

Sweet, opens up a lot of options for final drives then

Liking the M50 box swop in too