Originally Posted by Cobra4B
People always say the car revs quicker... is this meaning that the car is accelerating faster?
It should. The lightweight setups like Fidenza's reduce the weight of the Clutch/Pressure Plate/Flywheel by nearly 50% (something like 25 pounds). Besides the obvious simple benefit of the overall reduction in weight, the reduced mass means the rotational intertia of the assembly is also much lower. That rotational intertia looks like a much larger load to the engine that the weight alone would imply. And it takes HP to accelerate that flywheel mass as the engine speeds up. Reducing the rotating mass makes more HP available to the rest of the drive line, and that allows the rest of the driveline to accelerate faster. Since the car is attached to the driveline, it accelerates faster, too.
Because of inertia, rotating masses actually have an effect disproportionate to their actual weight. Reducing rotating mass is always a good way to improve acceleration. It pays back more than just the LBS you take out of the system.
Note that wheels also matter. They rotate, usually weigh as much or more than the clutch/flywheel assembly, have a larger diameter, and of course there are 4 of them. Interia varies with the square of radius, so the same weight hurts more in a road wheel than a flywheel. While I have no science to back it up, the rule-of-thumb I've heard is that every LB of rotating wheel weight is the equivalent of 4-5 LBs of dead weight.
You don't actually get more HP from the engine, of course, but it ends up looking that way to a dyno (and Seat Of The Pants). Since the inertia only consumes power when it's being accelerated (I'm totally ignoring friction here), the top speed of the car is unaffected (but you get there quicker).