Aluminum Racing Alternator Pulley +$5 Anodized in Black Upgrade/Performance/Race Billet aluminum reduction alternator pulley for the M10 engine. It is larger in diameter than stock (5"), so it slows down the alternator for reduced power loss at high RPM (most alternators produce full electrical power at modest RPM, so it's a waste to spin them faster). These are direct-fit for the later 65amp alternator with internal voltage regulator. They also fit the factory 45A 2002 alternator if you widen the keyway. Can fit on the M10, M20, and M30 engines. Installation Note: Since the pulley is a larger diameter you will need to run a longer belt. Made in the USA. Price: $94.19   Quantity to Add:   CONTACT US AT BMWSALES@2002AD.COM 1-800-4-2002AD 909-629-1955 outside of the USA COPYRIGHT © 2002 AD, ALL RIGHTS RESERVED.