450HP & 3.15 Gearing
Emission:
As for your question....
I thought about the same when I first installed the 3.15 differential because I knew I was going to S/C the car later on when Dinan supercharger becomes available. And I didn't want to loose too much top-speed because the car only has 5-speed (I rather my car to be Horsepower-limited a.k.a Drag-limited than Gear-Limited). Dinan tested a S/C 540i to drag-limited at almost 193mph.
The thing I found out after I installed the 3.15 is the RPM got up about 300RPM on every gear. Yes, the RPM seems a little high on normal speed (80~110mph) but I can live with it.
The good thing (which I realized later on after the 3.15) is when I floor the car at 160mph +, the needle of the RPM gauge gets high (5000 RPM +) in 5th gear and it actually slows down; while you see the needle of the speedometer goes MUCH faster than the RPM gauge.
I don¡¦t know what¡¦s the gear-limited top speed on the 3.15, a member of our forum has asked earlier and I did inquire at the other forum but didn¡¦t get a straight answer. Another thing is although the factory limits my gear to stop at 6500RPM, my 1,2,3,4 gears did go all the way to 7000+ RPM thanks to the Dinan download. I¡¦m going to try that on my 5th gear soon.
There are a few calculations from Roadfly members. They say the 3.15 goes up to 185mph and the 2.82 goes to 200mph, which I don¡¦t think it¡¦s rather high. Do you have any reliable calculations?
Also it was a task talking the pictures because I need to have my left knee controlling the steering wheel while holding the digital camera on my hand, and I have to push the button on the computer to see the actual-speed at the same time.
Phewww¡K. So much for a stupid move! Well worth it IMHO. I'm a crazy man, and crazy man does crazy things.
