Quote:
Originally Posted by intoflatlines
When accelerating hard it seems like there's a big loss of power before the 8000RPM redline (maybe around 7800RPM or so). Is this normal?
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Here's a graph from datalogging the ECU of my Z4MC during an acceleration in 2nd gear with the accelerator pedal held to the floor and allowing the rev limiter to kick in. I've recorded, Engine RPM, Vehicle Speed, Absolute Throttle Position and Calculated Load.
For some reason, the Absolute Throttle Position on the Z4MC at WOT records as being 76.1% rather than 100%, whilst the Calculated Load records as 100% (I don't understand why this is the case, but some other cars also do this. Can anyone explain why ATP at WOT is less than 100%?). Since the throttle of the Z4MC is "drive by wire" the graph shows that the
actual throttle position is reduced from WOT after the revs reach 7631rpm although the accelerator pedal was fully depressed. Therefore, it seems that the software is already commencing to reduce the air ingestion in anticipation of the engine rev limiter cutting out at 8,000rpm.
Quote:
Originally Posted by intoflatlines
What RPM do you recommend shifting at for maximum acceleration (stock)?
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The slope of the plot of engine rpm above 7,631rpm begins to fall away, therefore, I would suggest that the optimum rpm to gear shift is just as the needle reaches the amber zone in the tachometer. At this point you have also reached peak power output.