Quote:
Originally Posted by Boss330
You can NOT have 0% drivetrain loss... A 0% drivetrain loss would mean that there is NO power required to turn the transmission, driveshaft, differential and rear wheels... That is simply not possible 
Nor have I heard of any manufacturer claiming 5% losses either. It's generally accepted that drivetrain losses usually are in the order of 10-20% depending on type of transmission etc.
A few points:
-Dyno numbers varies according to type of dyno, operator, and numerous factors that influence the actual recorded whp on the dyno
-A whp number on a rolling road dyno is best used to verify before and after mod gains. It's not an exact tool to verify manufacturers crank HP claims
-It's generally agreed that the M5 is underrated, meaning that a 560whp reading on a dyno doesn't mean you have 0% drivetrain loss...
If we shall comparo dyno results. We at least need to know the type of dyno, correction factors etc. The same car might get 500whp on one dyno and 560whp on a different dyno...
560hp and a 15% drivetrain loss is 476whp, 12% loss is 493whp
600hp and a 15% drivetrain loss is 510whp, 12% loss is 528whp
If we look at a test done on a MAHA dyno, the same as used by manufacturers and test facilities here in Europe. You will see that they also display the drivetrain losses and that is as much as 120-140hp... The MAHA is supposedly the more accurate dyno, and is why you don't see inflated whp numbers. The dyno actually measures the losses in the drivetrain (or how much power it takes just to get it from the crank and to the rear wheels).
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Yay for reading into my post and being overly factual
I guess I should have clarified that whatever numbers the car put down there would be a % of drivetrain loss. All I did was base a percentage off the BMWUSA stock post crank numbers... What you did [and proper I'm not denying that] is find the actual HP then deduct the proper 15-20% or whatever % it maybe]
Quote:
Originally Posted by swamp2
As Boss330 mostly explained, drivetrain losses are not a correction or "fudge factor" simply showing the difference between stated and measured power. It is best to increase the clarity of such statements are use an actual crank hp measured and a fixed drivetrain loss. Granted getting the latter is not easy, thus most dyno guys use some fixed value and often 15%. It's really a shame if folks call your number a 5% drivetrain loss as that is physically impossible and really impedes understanding. Buck the trend, post the right way to discuss such numbers.
Boss330: Can you please translate the quantities in the upper left hand box of results?
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Its really a shame if you don't acknowledge the 63tu is coming underrated [like n54,n55]
but I guess you win post war haha...
And FYI while it may not be correct to say 554whp is 2% drivetrainloss of stock listed crank numbers[560] as BOSS explained... Nobody was trying to "fudge numbers" to win a posting war lol just show you that new M's (I know its hard with the NA
) are coming underrated, and its reasonable to assume this car will too.
As you went off saying lets use 15% off stock crank numbers which wouldn't be a wise starting point either as even the f30 335i's were underrated as seen below.
http://www.f30post.com/forums/showthread.php?t=652127