What is a flywheel and what happens when its lightened?
The flywheel is attached to the crank, its primary function is to smooth out the transmission of power from the crank (clutch engages the flywheel -> drives the gearbox -> and turns the driveshafts moving the wheels – bingo!!), this requires weight, however weight can also act as a resistance. Getting a flywheel lightened and balanced (through machining) can give you a more free reving engine, ie improving the engines response to throttle openings, however this will NOT increase power output. In addition, tuning an engine usually results in a shift of power up the rev range, losing torque at low revs, a lightened flywheel will greatly exagerate this loss of torque at low revs decreasing driveability.
