What is the best differential ratio for supercharged M3 ?

[Zezorro]

Hi guys I have supercharged M3. I am planning to rebuild my differential , right now I have stock unit. I will probably go with Wavetrac but I am not sure about ratio . I think I stay with stock 3.62 but I am curious if somebody tried shorter or longer gears and how can compare to stock 3.62 . Thanks for any opinion .

[ridebikes]

You may want to check out and post in the FI forum here: https://nam3forum.com/forums/forum/m...rced-induction

[bjz!]

Stock is great.

[Sharocks]

A 3.91 would wake up the low end and not be terrible on the highway.

4.10s are a tad too short for street use.

I know turbo guys swap in 3.15's to stay in gear longer so they stay in boost longer haha

[Rudbari]

4.10 with supercharged was fun but 1st , 2nd are useless and car go throw gears so fast .
swapped 3.62 and car feel nice and stay longer in boost .

I would be interested to see 3.85 on supercharged.

[old///MFanatic]

What type of Supercharger?

What kind of use do you want it to perform best at: drag, track, street?
Because what’s good for one use often isn’t optimally good for the other.

[Zezorro]

What type of Supercharger?

What kind of use do you want it to perform best at: drag, track, street?
Because what’s good for one use often isn’t optimally good for the other.

old///MFanatic Active autowerke with methanol injection. Mostly street driving . This is weekend car.

[EthanolTurbo]

Stock is the most balanced for a supercharger IMO.

[old///MFanatic]

I went taller (numerically lower) on my previous SC E46. You want the power in the power band the longest with traction to the ground. I can’t imagine you’re FI power now is doing much traction through 2nd. But granted that’s during launch and if your not doing stoplight racing that’s not as much a factor.
I’ll let others chime in but I would be surprised if 3.45 isn’t a better match keeping the most useable power band.
I don’t see 3.91 or 4.10 being optimal with the SC power band. You’re up and out of it too quick. imho

[bmw m3 s50]

I had both 3.91 and 4.10 diff with my Stage 3 AA supercharger. I loved both the diffs. I had the 3.91 longer then wanted more so upgraded to the 4.10. It definitely helps and wakes up the car. Traction is dependent on your right foot. Car pulls like a freight train and gives the s54 that extra grunt. I would recommend the 4.10 but if you prefer something more mild the 3.91 will work beautifully. The problem is you will get used to the 3.91 and want more which is what happened to me.