NASCAR engines do not stay at peak RPM for the full race, they are up and down, some races RPM varies a lot, some not so much. I agree though, a Pro Stock motor cant get a mile or 2 out of valve springs versus several hundred out of a NASCAR set, something is vastly different. I am sure NASCAR does not put quite as much emphasis on how fast the engine accelerates.

What horsepower per cubic inch does a NASCAR engine make? Just over 2? A Pro Stock motor makes almost 3, so I guess some the extra power is made at the sacrifice of valvetrain longevity.

Danny