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View Full Version : Diff. Change in Sc'ed car?

0hMyGod
08-30-2004, 10:41 AM
Does anyone did this? If so, what ratio did you get?
Or What ratio would be good? :dunno:
Thanks in advance.
drhendrix
08-30-2004, 11:29 AM
Does anyone did this? If so, what ratio did you get?
Or What ratio would be good? :dunno:
Thanks in advance.

Hard to know without knowing what your car is, but . . .

Mine is a 330i with a stock 2.93 ratio. It is geared to go 150mph in 5th gear at 6500 RPM. Potential swaps are

3.07 . . . . 5% torque increase . . . . . . 6500 RPM in 5th @ 143mph
3.15 . . . . 7% torque increase . . . . . . 6500 RPM in 5th @ 140 mph
3.23 . . . . 10% torque increase . . . . . 6500 RPM in 5th @ 136 mph
3.38 . . . . 15% torque increase . . . . . 6500 RPM in 5th @ 130 mph
3.46 . . . . 18% torque increase . . . . . 6500 RPM in 5th @ 127 MPH

If I do a diff swap, I want to go 3.46 and swap in a 6 speed.
Alan L.
08-30-2004, 12:11 PM
If you already have step, thats already the lowests (numerically higher) diff you can get which is a 3.46 in your 328.
0hMyGod
08-30-2004, 12:14 PM
Thanks for input.
I'm swapping these to lower number, cuz I will get the manual tranny soon. (unless I find real strong auto tranny) :)
Any idea about what ratio should I get?


BTW, I remember one member has alpina auto tranny, Do you know who has them? and how much power can it handle? :dunno:
Nt_loader
08-30-2004, 12:45 PM
I went with a 3.15 in my 330i 5 speed
erick-323i
08-30-2004, 08:09 PM
Got a 3.46 with a 5 speed... its a daily driver too; not bothered by the high revs :)
0hMyGod
08-31-2004, 12:03 AM
Got a 3.46 with a 5 speed... its a daily driver too; not bothered by the high revs :)
:wow: You are not bothered. :rolleyes: That's good.

So what if I wanted to get the 6speed tranny? :shhh:
Which one would be the best? :dunno:
djyoungz
08-31-2004, 12:20 AM
maybe you should consider doing a level ten upgrade or something... That might be a good idea....
samir@technik
08-31-2004, 12:48 PM
If you don't mind slightly higher revs on the freeway, then I would go as high as 3.64 (from the Z4) or even 3.91 from the (320i).
0hMyGod
08-31-2004, 07:28 PM
If you don't mind slightly higher revs on the freeway, then I would go as high as 3.64 (from the Z4) or even 3.91 from the (320i).

Thanks for input.

Technik= what kind of rpm would I get when I'm cruising?(say 80?) :dunno:
djyoungz= I was looking into that, but no review and don't wanna spend money that are not proven. :thumbup:
Exacc
08-31-2004, 07:44 PM
Go to this site, it should help...http://www.368s.com/tools_rpm.phtml
0hMyGod
08-31-2004, 07:48 PM
Go to this site, it should help...http://www.368s.com/tools_rpm.phtml

Thanks.:thanks: :thumbup:
erick-323i
09-01-2004, 07:31 PM
Higher revs means higher boost if im not mistaken :thumbup:

dunno about getting a 3.91 diff :wow:... maybe for racing only; 3.46 is pretty high IMO.
beanfree
09-01-2004, 11:06 PM
Higher revs means higher boost if im not mistaken :thumbup:

dunno about getting a 3.91 diff :wow:... maybe for racing only; 3.46 is pretty high IMO.

Can you spin the wheels with your 3.46 diff. Would think that a supercharged car would have enough torque to spin the wheels with the stock differential.