BMW diff ratio Gurus!

[drifty340i]

Hi Guys,

As some of you may no im just about to fit a v8 to my 325i. I currently run a 3.73 lsd diff and the car is running at about 2750rpm at 100kph (60mph).

Now the car will put down around 260hp atw with the new v8

and more low down tourqe (more than a turbo m20 at low revs). im changing the gearbox to a w55 supra gearbox with these ratios

W55: 1st 3.57:1, 2nd 2.06:1, 3rd 1.38:1, 5th 0.85:1

First question what will my car be revving at with the 3.73 and the toyota box 100kph? approx

Second question, i have a 2.93lsd avaialible, what will this be revving at 100kph with the toyota box ratios? approx

An is this diff as strong as the 3.73lsd?

Any help would be so so awesome

cheers

Riley

[drifty340i]

Really i just want to know what diff would suit this setup best? i know it will get off its arse very quick with the v8
and a 3.73, but im afraid it will be revving to high and all that tourqe will be wasted.

Im also a bit worryed that the 2.93 may be a bit high ratio, and to low in the revs, and not so good off the mark?
thoughts ? cheers

[reelizmpro]

2.93 should be fine...try it and see if you like it. Next step up is 3.15 and 3.25.

[browntown]

google unixnerd, he has a calculator where you can plug everything in and get speeds at rpm for each gear and different final drive ratio, stop guessing and let his java calc do the math. I'll save you the search, here's the link http://www.unixnerd.demon.co.uk/bmw.html Click on "gearing calculator" in the left hand navigation pane.

[drifty340i]

Whoa sweet thats so so handy!

@ 68mph (110kph) with a 2.93 diff ill be revving at 2400rpm.

@ 68mph (110kph) with a 3.73 diff ill be revving at 3050rpm

Looks like the 2.93 is the go.

@ 52MPH (overtakeing start area) its revving at 3845rpm Perfect for a v8!

[Ray Smoodiver]

Darren's diff you cheeky man? I was planning on mating that to a dogleg!

[drifty340i]

Darren's diff you cheeky man? I was planning on mating that to a dogleg!

Na mate not Darrens lol, its all yours. Ive got a swap lined up with Gary.

[2002maniac]

http://www.f-body.org/gears/

[Garageaholic]

I have created an excel spreadsheet. Anybody want it, just email me and i can send the excel file. here is a look at it

[drifty340i]

cheers guys! mint

[euroshark]

How does the supra gearbox fit the BMW V8? I am curious.... that's so tempting!

[drifty340i]

How does the supra gearbox fit the BMW V8? I am curious.... that's so tempting!

Its a lexus v8 1uzfe,all alloy quad cam 4.0l, 280hp:)

[euroshark]

Ahhhhh, that makes perfect sense!

[drifty340i]

lol would be nice if it would mate upto a bmw v8 ,but no such luck