V8 hommies... what differential?

[bmk]

Yeah i would ideally like an 3.46 but I cant find one. Ive been heavily searching for the past 1.5 months

[GAbOS]

What diff is everyone running? I want something that will give me a good mix of highway acceleration and decent highway mpg (20 mpg). My car will be right around 400hp/400tq 3200lbs I am using a t56 6 speed 1st: 2.66:1 2nd: 1.78:1 3rd:1.30:1 4th:1.00:1 5th:0.74:1 6th:0.50:1
Curious on your guys input from guys that drive v8 e30's.

Thanks!

If his ratio's are correct, and I will 'assume' a 225/50/16 here to get a middle ground for 16 to 17 ifies.

3.73
6th will get you to 80mph at 2000rpm or 119 at 3k
1st will get you to 45mph at 6000rpm
4th will get you to 119 at 6000rpm

You are 5 - 7 mph faster with the above calcs against a Getrag 420g 6spd and a 3.15 rear diff. That is, until 4th. The Getrag hits 1.00:1 in 5th and only .83 in 6th (2000rpm = 57mph in 6th).

[Madhatter]

I missed your curb weight in the first post.

There are 3.46 medium case gearsets available... not sure any were used in E30 cases, though, so you may have to build one.

323i's. Though it won't help you guys much in the US. Not sure what early 325e and 325i cars came with over there. I know some E28's came with them too. 528i for example I think.

[FredK]

Yep. In the US the E28 528e automatics often came with S3.46 diffs. It depended by year, though.

[Wanganstyle]

Yep. In the US the E28 528e automatics often came with S3.46 diffs. It depended by year, though.

Modern option would be z3 3.0 auto

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[jannmann]

I will go 4,27diff with my Alpina F3 V8.
6speed getrag 420g. Primary use is track.
I'l get aprox. 240km/h top speed (max rpm 7500)
That leave 5 gears to use(2-6). I block first gear mechanically.

[jalopi]

I block first gear mechanically.

why? some sort of rally setup?

[jannmann]

why? some sort of rally setup?

It's only going 27km/h with first gear. So i don't need it. With second gear it goes aprox. 70km/h. That's peace of cake to 4,6l engine sitting car under 1100kg.

Also I can keep my car original gear knob in place :)

[bmk]

If his ratio's are correct, and I will 'assume' a 225/50/16 here to get a middle ground for 16 to 17 ifies.

3.73
6th will get you to 80mph at 2000rpm or 119 at 3k
1st will get you to 45mph at 6000rpm
4th will get you to 119 at 6000rpm

You are 5 - 7 mph faster with the above calcs against a Getrag 420g 6spd and a 3.15 rear diff. That is, until 4th. The Getrag hits 1.00:1 in 5th and only .83 in 6th (2000rpm = 57mph in 6th).

Yeah in the T56 Both 5th and 6th are overdrive gears thats why im thinking maybe a higher ratio wont be so bad. They certainly are much easier to find than a 3.46 that I want.