Quote:
Originally Posted by jeremyc74
Not to take away from the numbers he put down, but you're reading too much into it. The 15% driveline loss is a guess, and it's hard to actually prove without doing an engine dyno and then a chassis dyno. On top of that you never know how exact the calibration on the dyno is. The factory numbers are standardized and are adjusted for a specific set of circumstances (temperature, oil level, fuel, altitude, ect.). If you run the car at a lower temperature you're going to see better numbers. In other words, too many variables to say BMW is actually under-rating the cars.
Numbers from a chassis dyno should be used as a tuning tool to demonstrate gain. Trying to derive exact flywheel numbers from them isn't really useful.
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you are correct to a certain point. Conversely, if we assume that the 302hp rated power from BMW is the "correct" baseline, then according to these numbers the drive train loss factor is:
273/302 = 0.9
thus
362/0.9 = 402 hp, baselined from a 302hp initial value.