big flywheel will cost u torque
if it was a motor that sat at one rev
u would have the torque of the motor and
the inertia in the fly wheel to do the job
if u try to rev the motor u will use up
the torque to speed up the flywheel
wats left will push the car
lighter fly wheel will let it rev faster and be more responsive
heavy fly wheel will idle lower,smoother,and will be more tractable(less wheel spin)easyer off the line,harder to stall
if running a blower there is a lot of fly wheel weight in the blower(cost hp torque)to spin
the less rotating mass the more torque to push the car and rev out quicker
henc lightening crank,rods,pistons,ect any thing that is driven
polished and knife edge crank,dry sump ect reduces the drag on the rotating mass, more torque