Underdrive Power Pulleys work to 'free up' horsepower. Any accessory that spins from the main drive belt is using up power. That's power that could otherwise be used to move the car. By giving some of that power back to the engine, you can make the car faster! It's like FREE HORSEPOWER! We measured 10.7 whp at 6960 rpm and 8.1 lb-ft of torque at 5550 on a 1995 M3.

Underdrive pulleys for your BMW will slow down engine-mounted accessories - the water pump, power steering pump, and alternator*. These systems contribute to 'parasitic losses' - power lost from what the engine could produce if it did not have these systems. Since less energy is used to move them, that power is transferred back to the engine and used to propel the car. Our pulleys give a 10-20% reduction in rotation, releasing up to 11hp on most BMW six-cylinder engines. There's also a small but noticeable improvement in throttle response too! We have done extensive testing and development work, both on and off the track, to ensure that the accessory systems function as they should. On our Racing pulley kits we actually underdrive certain components more so we feel our Street pulleys are an ideal compromise between power/torque gains, reliability, and system performance. Our pulley kits have been on the market for over ten years, and used in all of our own cars, with zero component failures related to their use.

Our pulleys are made from T-6061 aluminum and finished in a durable black hard anodize that is very resistant to wear, chemical exposure, and heat. We designed our pulleys to look similar to the factory parts but also to be stronger and, in most cases, slightly lighter too. For example, a Turner alternator pulley is less than half the weight of the stock steel pulley! With our hardcoat aluminum you will never have to worry about a serious failure of a stock plastic pulley. A 'stealth' approach to aesthetics was our goal and we let the results speak for the pulley design. Installation is straight forward and easy with simple hand tools. Removal of the fan is required for access to the front of the engine. Total install time for a 3-piece pulley set should be around 1.5 hours. A new longer belt is included and we also recommend replacing the separate A/C belt, belt tensioners, and the guide and deflection pulleys at the same time.

This pulley is mounted along with the hydraulic belt tensioner but can be replaced on its own. It is used for the main drive belt on the M50-M54 family engines (M50, M50TU, M52, S52, M52TU, M54, M56, and S54 engines). This is the same belt that covers the water pump/alternator/power steering systems. Replacement is a very easy procedure (requires fan removal) and will have your engine purring in no time. Belt replacement is strongly recommended at the same time. If you have a mechanical belt tensioner, the pulley can only be replaced with a new tensioner.

This high-quality replacement from Bremmen Parts is designed for exact fitment on your BMW. Whether you're looking to complete much-needed preventative maintenance, or replacing a failed roller, choose this component from Bremmen Parts for a lasting repair.

If you need the hydraulic belt tensioner, click here.

This item is 70mm Diameter. Please check the diameter before ordering.

This tensioner pulley fits the following BMWs: 1991-1995 E34 525i (M50 engine) 1992-1999 E36 325i, 325is, 328i, 328is, 323is 1995-1999 E36 M3 (M3 3.0 & M3 3.2 liter) 1997-2003 E39 525i, 528i, 530i - Only for Hydraulic Tensioner 1999-2000 E46 323i, 323Ci, 328i, 328Ci - Only for Hydraulic Tensioner 2001-2005 E46 325i, 325Ci, 325xi, 330i, 330Ci, 330xi - Only for Hydraulic Tensioner 2001-2006 E46 M3 coupe & convertible - Only for Hydraulic Tensioner 2000-2006 X5 3.0 liter (E53 chassis) 2004 E60 525i, 530i (M54 engine) 1997-2002 Z3 & MZ3 2.5, 2.8, 3.0, M Roadster, M Coupe 2003-2009 Z4 M Coupe and Roadster