Each time the air/fuel mixture inside a cylinder is ignited, the combustion that occurs creates a torque spike that is applied to the crankshaft through the piston and rod. This torque spike is so severe that it not only turns the crankshaft, it actually twists the crankshaft ahead of its normal rotation and then the crankshaft rebounds. This twisting action is known as torsional vibration. When these torque spikes and forces get into phase with the natural frequency, critical torsional harmonic vibrations occur and can be seriously destructive to the bearings and the crankshaft. the stock crank pulley works, and it'll be okay, but if you're modifying your engine, you're throwing out the overall balance created in the engine from the factory, necessarily increasing the forces being applied on the internals of the engine as you increase HP. Getting a lightened pulley will lower the pulley's ability to absorb the vibrations from your engine and will cause your internals to experience excessively more wear. Dampers are designed to control those destructive vibrations.i will be using a fluidampr soon. they have fluid in the pulley's to absorb the vibrations and keep wear to a minimum. using a lightened crank pulley is like putting oil from a gas station in your car and only changing it every 8000 miles.
