STILLEN lightweight crank pulley

Josh@STILLEN

This is a harmonic dampener of sorts, on that point you're exactly right. But it's not to balance the engine, it's to balance the pulley ITSELF.



The factory pulley is NOT balanced, and the dampening employed on the pulley is to protect the engine from the outside influences going inward.



The factory pulley is a rough casting, done this way for cost reasons. To cut the entire pulley out of 6061 billet aluminum and balanced is an expensive proposition. They chose to cast the pulley, and add a rubber insulator to act as a dampener. Some other things can assist in dampening, the rubber belts and tensioners in the serpentine belt can help with NVH, and suitable when using a balanced pulley.

You can see the differences in the quality of the part...

400370 - Underdrive Pulley




400338 - Standard Lightweight Pulley