Quote:
Originally Posted by M3ToolFiend
I wasn't comparing forced induction w/ N/A, but if you must...
The reason forced induction engines have greater "capacity" as you call it is because forced induction raises the pressure of the intake charge, effectively raising the compression ratio, which is the driving force in engine power and efficiency. If you look at the formula for BMEP, (Brake Mean Effective Pressure), you'll notice in the numerator is the compression ratio.
What I was saying, however, was that BMW gets similar HP to a Merc engine, and they do this w/o forced induction, and with smaller displacement. That's impressive. If BMW built a 5.5 L Supercharged V8 a la the E55, they'd probably get it up yo 650 HP. Although, I have to admit, that engine was definitely downtuned, that's why AMG's are much easier to tune. I mean Brabus gets ridiculous numbers.
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You can hide a lot of poor engineering with displacement. AMG and even the mightly LS7 have huge displacements, this works great for America but consider the tax penalty in countries they tax displacement.
How many 5.0 liter + engines do you see from BMW? I think none....
Different design goals and I agree with if you can BMW engineers to design and build a big displacement engine, they can do as well as AMG or Chevy. The question is can AMG or Chevy do what BMW can do with a fixed displacement and no forced induction?