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      05-20-2010, 08:19 PM   #25
swamp2
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Drives: E92 M3
Join Date: Sep 2006
Location: San Diego, CA USA

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Quote:
Originally Posted by gr8000 View Post
According to my calculations, the (theoretical) top speed at 8,400rpm for the stock 6MT and DCT is 302km/h and 321km/h respectively (assuming that the engine is allowed to rev up to the redline in the top gear on each car and assuming that it has enough power!).
If you really want the last bit of accuracy use the revs per mile calculation for tire size rather than the standard calculation:

Tire diameters are: std. calculation:
Without tolerances: [(265 x 0.4) x 2 + (18 x 2.54)] * pi = 2.10 m

Michelin website:
63,360 divided by revolutions pre mile = rolling circumference in inches:
For the 265/40ZR18 PS2 Michelin states 790 revs per mile so 63,360 / 790 = 80.202 inches = 2.037 m.

Also, you can add a drag calculation to get Vmax as well. The M3 is first limiter limited and if removed drag limited. The tricky part of getting a Vmax calculation correct is knowing drivetrain and tire losses. See my post here.