Originally Posted by pokeybritches
Actually, at equal boost levels, a centrifugal supercharger generally puts out less peak torque than any of the major forced induction mods (centrifugal, roots, twin screw, turbo).
Horsepower = torque * rpm / 5252
To produce more power over time (horsepower), you can either increase the "boom" (torque) each time a cylinder fires, or increase the number of times that boom occurs (rpm). The reason turbo cars generally have more power throughout the rpm band is because they produce more torque.
The S54 gets its power (and character) through its the sky high redline. For years, BMW M division shunned turbos, and opted instead to design cars to handle increased rpm rather than high torque. This requires tight tolerances and exotic materials, and reduced engine reliability (rpm is an engine killer)... but makes for a very exciting and peaky car. They finally caved when rpm couldn't be realistically increased further, yet they had to produce more power to remain relevant and competitive. The S54 was the final, maxed out, ultimate iteration of the old school M division's high rpm vision.
Like most street engines, the S54 becomes less efficient the higher you rev it (torque falls off as rpm increases, because the engine isn't able to fully replace the used air in a cylinder with fresh air). A centrifugal supercharger adds torque back where it normally would start to fall off. It keeps with the character of the car. The traits that make it spectacular aren't lost.
The reason I think that Frankensteining the car into something it wasn't intended to be (like a 60-130 mph record holder) is a bad idea, is because you can get there so much cheaper with another platform, and you would have to give up most of what makes this car so awesome. It's like taking a guy who successfully competed in American Ninja Warrior, and putting him on a workout plan to bench 4 plates. He could get there with a lot of time and effort... but why? He certainly wouldn't be lean and agile enough to do what he used to do (which very few others could do). Once you swap to a clutch that can handle the torque, put on some massive tires and do suspension/body work to handle the power, and throw in some turbo lag... try and do an autocross. I'm not saying that a 650 whp car isn't fun, but I think there are better ways to get there. In this car, a lot of what you're paying for are the things other cars struggle to achieve.
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