[MKE_M3]

Originally Posted by JoeFromPA

First off, haven't you ever heard you can't compare dynos across different machines? A normal dyno to dyno comparison may be 10% different.

Now we are comparing expected wheel dyno output to BMW benchmarked engine dyno? This is getting ridiculous.

Turbo engines are very volatile to external factors. Heat soak, fuel grade, air flow to the engine. They are more likely to have larger swings on a dyno.

BMW MAY not be under-rating, but instead be producing an engine dyno rating that can be consistently achieved using lower quality fuel, some heat soak, and non-ideal air flow or air density (i.e. providing a dyno that's accurate at 4000 feet elevation)

But hey, let's all ignore the actual science and possibilities here and claim "under-rating compared to my sea level, Joe's mustang dyno + massive fans dyno which measured the output at a completely different part of the car and applied an unscientific adjustment for parasitic loss!"

Well said