2013 BMW M5 may have more horsepower than reported

[LeMansX5]

From Bimmerboost.com:

We knew the upgraded S63tu (technical update) Twin Turbo 4.4 liter V8 in the F10 M5 would be stronger than the standard S63 Twin Turbo V8 4.4 liter units in the X5M and X6M even accusing BMW of sandbagging. We just did not think it would be this much stronger. We first reported on the differences between the S63 V8's in the M SUV's and the F10 M5 in June of last year and the M5 S63tu V8 has higher compression at 10.0:1 versus 9.3:1 and runs more boost at 22 psi versus 17 psi for the SUV's.

Well, the end result is 527 rear wheel horsepower completely stock on pump gas. This dyno comes to us courtesy of our Premier Vendor IND-Distribution whom we thank for sharing it with us.

To put this power in perspective, the X5M and X6M put down 456 all wheel horsepower stock on 93 octane in SAE on a dynojet. So the M5 is much, much stronger partially due to routing the power to the rear wheels with a dual clutch transmission versus all four with an automatic and also due to more boost with higher compression.

For those who like to calculate drivetrain losses, the M5 is rated at 560 horsepower stock. That would put the drivetrain losses at 6%. Using the traditional dynojet standard of 15% the rear wheel horsepower should be at 476. BMW is underrating the new turbo motors and especially the M motors considerably. We are definitely glad they are over-delivering.