Dinan Underdrive Pulley Kit for S85 Street Version

Dinan's lightweight billet aluminum crankshaft pulley underdrives each of the accessories by 13%, reducing parasitic drag on the engine for a 6 horsepower and 4 lb-ft torque gain.The Dinan underdrive pulley retains the factory harmonic crankshaft damper, eliminating vibration that might otherwise damage the crankshaft.

The kit includes all of the necessary mounting hardware, lightweight pulley and shorter belts.This product is backed by our industry leading 4 year/50,000 mile warranty so you can rest assured that you are purchasing the best quality product for your BMW.

6 horsepower @ 8000 rpm and 4 lb-ft torque @ 8000 rpm on a stock car.