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 OEM Ruville hydraulic tensioner assembly is designed to keep the serpentine belt at the correct pressure against the pulleys. Many BMW's can have either a hydraulic or mechanical belt tensioner. Please check to see which tensioner type you need before ordering.

OEM Schaeffler (INA, LuK, Ruville, & 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 item fits the following BMWs:
1992-1998 E36 BMW 323is 323ic 325i 325is 325ic 328i 328is 328ic M3
1999-2005 E46 BMW 323i 323ci 325i 325ci 325xi 328i 328ci 330i 330ci 330xi M3
1991-1995 E34 BMW 525i
1997-2003 E39 BMW 525i 528i 530i

If you're grappling with issues like crankshaft failures and oil pump breakdowns in your BMW 6-cylinder engines, you're not alone. Even seasoned mechanics can overlook the critical aspect of harmonic resonance control in these inline-6 motors, despite their optimal configuration.

Enter ATI Performance Products in collaboration with VAC Motorsports, presenting a solution in the form of new dampers tailored for BMW 2.5L, 2.8L, 3.0L, and 3.2L straight-6 engines found in various models like the E36 and E46 M3, E9X, and E6X, as well as newer Z3s and Z4s. These dampers effectively nullify crankshaft harmonic vibrations, paving the way for enhanced horsepower and torque output, alongside a reduction in internal engine wear. Say goodbye to issues like fractured oil pumps and timing chain mishaps! By pairing these dampers with a VAC accessory pulley, you seamlessly replace the OEM balancer. Featuring a 7” outer diameter and OEM-style timing alignment tabs, these ATI Super Dampers boast SFI 18.1 Safety Certification, ensuring they're competition-ready.

What sets the ATI SuperDamper apart? It's the remedy for vibration woes in inline 6 engines, especially those equipped with lightweight clutch and flywheel setups. Expect diminished wear on bearings, engine accessories, and oil pumps, all while being compatible with underdrive pulleys.

Included in the kit are the damper itself, a lightweight VAC Billet Crankshaft Pulley, along with all necessary mounting and installation hardware. Note that it's not compatible with S50B30 & S50B32 Euro Engines. For street/track vehicles with air conditioning, opting for the Additional A/C Pulley Option is imperative, given that the OE A/C pulley isn't compatible. Rest assured, all required mounting and installation hardware is included, and the entire package is proudly Made in the USA.

Also known as a shock damper, the accessory belt tensioner is used to tension the air conditioning compressor belt. This ensures proper contact with the belt drive pulleys and prevents premature wear from improper tension.

If your belt is wearing prematurely or has excess slack, your belt tensioner may be to blame. Replace it with this high-quality Bremmen Parts tensioner to ensure proper tension and air conditioning functionality.