View single post by Jensen Healey
 Posted: 10-20-2013 02:34 pm
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Jensen Healey

Joined: 03-11-2005
Location: San Anselmo, California USA
Posts: 976
A flywheel stores rotational energy. It helps smooth the power output and maintain constant cruising speed.
In a stock engine the pistons and rods are not all the same weight. Even the crankshaft isn't perfectly balanced. An aluminum flywheel would allow you to feel these imbalances.
It does take some of the available torque to spin up the flywheel during acceleration. This is why racers use lightweight flywheels. They don't care about smoothness or maintain a constant cruising speed.
By the same logic, if you rev the engine to 4000 rpm and dump the clutch, the energy stored in the flywheel will be added to the available torque. Good for smoking the tires.
There can be a seat-of-the-pants improvement in acceleration in 1st gear at lower rps's. Since the 907 is weak in this range, a modest reduction in weight makes for a nice improvement in drivability. An aluminum unit will probably be to touchy for normal street driving. Lotus used a steel flywheel on later engines that weighed in at 13lbs which is ideal for a modified and balanced street engine.
Order one from Mike at if you intend to race.