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      06-04-2013, 10:37 PM   #84
Brigadier General

Drives: 130i
Join Date: Nov 2011
Location: QLD, Australia

iTrader: (0)

Originally Posted by CanAutM3 View Post
Swamp is correct. The M5 does not need to be shifted at red line in the higher gears as clearly indicated in the graph. This is also true for the 1M. I came to the same conclusion with a similar analysis previously.

To me, this is also an indication that the gear ratios on the M5 were not optimized for best overall acceleration (maybe a compromise for MPG and/or comfort ). 1st, 2nd and 3rd are too far from each other while 4th, 5th, and 6th are too close. I would keep 7th with a taller gear for MPG. Choosing gear ratios that would allow the force line of every gear to touch the force line of the next higher gear without crossing would yield better acceleration over the entire range.

My hope is that the F8X M3/M4 DCT ratios are better optimized to take full advantage of the new engine.
1m/n54 is totally different, they make peak power in the midrange (5500-6000rpm, and taper HARD to redline, WAY more than the M5/M6 taper.

1m/135i you shift at 7000 in 1-2 then after that it drops to about 6900, 6750, 6600 or something from memory.. certain people's tunes let them go to 7000 in 3rd as well, but that's a case by case basis.

even with the (somewhat unrealistic) torque curve provided in the OP, with the gearing also provided (at possibly off ratios)... using a calc, it's shift to 4th at redline, then the taper i put in is a bit higher than the OP, so 7,7, 7,6 as the ratios get REALLY close together with a REALLY steep taper.

pretty poor optimising of ratios, if they were a bit further apart, the whole rev range could be happily used AND it'd rev lower in top gear on the highway lol.

Last edited by flinchy; 06-04-2013 at 10:48 PM..