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 is an OEM INA AC Belt Tensioner with pulley for all 2001-2006 E46 M3, as well as all 1999-2002 non-M E46 3 series models. These belt tensioner units are known to fail, and include the tensioner pulley (as shown).

OEM Schaeffler (INA, LuK, & FAG) is an engineering company that focuses on high-performance, precision manufacturing. With their individual brands INA, Luk, and FAG providing exceptionally high quality parts directly to BMW, as well as countless other automotive companies, their history of reliability and variety of offered parts makes Schaeffler a go-to replacement parts provider for all of us here at Turner Motorsport.

As a leading source of high performance BMW parts and accessories since 1993, we at Turner Motorsport are honored to be the go-to supplier for tens of thousands of enthusiasts the world over. With over two decades of parts, service, and racing experience under our belt, we provide only quality performance and replacement parts.  All of our performance parts are those we would (and do!) install and run on our own cars, as well as replacement parts that are Genuine BMW or from OEM manufacturers. We only offer parts we know you can trust to perform!

This Air Conditioning / AC Belt Tensioner with Pulley fits:
1999-2000 E46 3 Series 323i, 323Ci, 328i, 328Ci
2001-2002 E46 3 Series 325i, 325Ci, 330i, 330Ci
2001-2006 E46 M3 coupe & convertible

For Alternator / Water Pump Belt

Hydraulic Belt Tensioner for E36, E46, E39 6-cyl models. This is the oil-filled tensioner that keeps the main drive belt in the proper tension. Over time the piston seals inside allow fluid to leak out. The tensioner becomes frozen or inoperable. Replacement is the best corrective action to take. This can be done during any belt or pulley service or anytime the fan is off the engine.

OEM Schaeffler (INA, LuK, & FAG) is an engineering company that focuses on high-performance, precision manufacturing. With their individual brands INA, Luk, and FAG providing exceptionally high quality parts directly to BMW, as well as countless other automotive companies, their history of reliability and variety of offered parts makes Schaeffler a go-to replacement parts provider for all of us here at Turner Motorsport.

As a leading source of high performance BMW parts and accessories since 1993, we at Turner Motorsport are honored to be the go-to supplier for tens of thousands of enthusiasts the world over. With over two decades of parts, service, and racing experience under our belt, we provide only quality performance and replacement parts.  All of our performance parts are those we would (and do!) install and run on our own cars, as well as replacement parts that are Genuine BMW or from OEM manufacturers. We only offer parts we know you can trust to perform!

NOTE: These BMW's may have been equipped with either a mechanical or hydraulic tensioner. Only for cars with Hydraulic Belt Tensioners. Please check 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
1999-2000 E46 323i, 323Ci, 328i, 328Ci
2001-2005 E46 325i, 325Ci, 325xi, 330i, 330Ci, 330xi
2001-2006 E46 M3 coupe & convertible
2000-2006 X5 3.0 liter (E53 chassis)
2006 525i, 530i(M54 engine)
1997-2002 Z3 & MZ3 2.8, M Roadster, M Coupe
2003-2009 Z4 M Coupe and Roadster

The OEM INA Tensioner Bearing allows the belt tensioner arm to rotate and apply pressure to the serpentine belt. With a bad bearing, the arm may seize up and prevent the tensioner from working properly.

OEM Schaeffler (INA, LuK, & FAG) is an engineering company that focuses on high-performance, precision manufacturing. With their individual brands INA, Luk, and FAG providing exceptionally high quality parts directly to BMW, as well as countless other automotive companies, their history of reliability and variety of offered parts makes Schaeffler a go-to replacement parts provider for all of us here at Turner Motorsport.

As a leading source of high performance BMW parts and accessories since 1993, we at Turner Motorsport are honored to be the go-to supplier for tens of thousands of enthusiasts the world over. With over two decades of parts, service, and racing experience under our belt, we provide only quality performance and replacement parts.  All of our performance parts are those we would (and do!) install and run on our own cars, as well as replacement parts that are Genuine BMW or from OEM manufacturers. We only offer parts we know you can trust to perform