So while accelerating, the heavier rotating assembly takes more power to accelerate (makes sense), but would it still not use more power (although considerably less than when getting up to speed) at a static RPM since you are still having to spin a heavier weight? Even at a static velocity, there's always acceleration when dealing with circular motion, is there not?.
Theoretically the entire rotating assy is just an energy storage device, basically one big flywheel. It soaks up energy as it accelerates, then gives that same energy back as it slows down. If that give/take were actually averaging out, there shouldn't be much difference overall in a heavy vs lite crankshaft/flywheel/clutch comparison. But there is a difference that I believe shows up on the time slip for two basic reasons...
1- lower launch rpm compared to the trap rpm. Basically if you were to launch a car at 6000 and trap at 8000, the engine will be burdened with creating enough additional energy during the run to make up that overall 2000rpm difference. Keep in mind the exponential effect that comes with rpm, it takes 16x more energy to accelerate that rotating assy from 6000 to 8000 as it did to accelerate it from 0 to 2000. In this case a lighter rotating assy is an advantage because it will absorb less energy while making up that 2000rpm difference between launch and trap.
2- less energy wasted during a post shift wheelspeed spike. The return of energy after the shift can be so intense that some of the energy released during fallback can be spent in non-productive ways, like knocking the tires loose for an instant. Because a lighter rotating assy releases less energy during fallback, that also reduces the amount of energy wasted as wheelspin after the shift.
Grant
