Reduce parasitic loss of power on your BMW's engine by safely under driving the belt driven auxiliary systems. Reducing this drag on your engine results in MORE HORSEPOWER AND TORQUE to the wheels of your BMW. Our BMW underdrive power pulley kits are specifically designed for each BMW application to make the best power while maintaining stock driveability and reliability, eliminating potential downsides. Others may advertise "their" pulleys boasting more power, but we concluded that for street and track driven BMWs, ours are the best size and design to ensure both your engine and it's belt-driven systems (alternator, water pump, power steering etc) are well within safe operation. We run these under drive pulleys on our own BMWs, so we would not want them any other way.
Available for the following BMWs: (click icon to change BMW)
As used on our racecars and street cars, these are engineered not only to be the best pulley kits on the market but also to provide the best compromise between performance and reliability. Specifically, we have designed them to underdrive the water pump, power steering pump and alternator*. Adding these is like getting FREE HORSEPOWER - there are no downsides and underdriving each of these accessories has been proven safe through years of on and off-track use. We do not believe it is safe to change the crankshaft pulley on engines with harmonic balancers due to the potential harm to the crankshaft. As such our pulley kit for the X5 3.0 does not replace the crank pulley, only the auxiliary pulleys. These kits provide a 10%-20% overall reduction in driving your car's systems and have been dyno-tested with a gain of up to 11hp.
Kit includes water pump, power steering, alternator pulleys and belt. The T-6061 hard anodized aluminum pulleys account for a 10 to 20-percent decrease in accessory speeds, reducing the load on the engine but still maintaining a safe margin for reliability on all components. Installation involves removing the fan for easy access to the front of the engine. The main drive belt comes off easy and each pulley is mounted with Allen head bolts. Typical installation time is 1.5 hours. New main drive belt is included. The pulleys were good for 10.7hp at 6960 rpm and 8.1 lb-ft of torque at 5550 on the 1995 M3.
*Alternator pulleys - we offer two kits, one for the performance minded individual and one for the serious audiophile. If you have a significant additional load on the alternator, from aftermarket audio amplifiers, you will not want to underdrive the alternator. Thus, we simply lighten that pulley rather then underdrive it. Choose from the menu below if you have a stock or an upgraded stereo.
BMW used both BOSCH and VALEO brand alternators, which use different pulleys. If you know which you have, select your option below and we'll be sure to send you the correct alternator pulley for your BMW. Don't know which you have? NO PROBLEM! Simply tell us you don't know which style alternator you have, and we will send you both pulleys. This option costs $64, but you will get a $64 refund once we get the unused pulley back. If you know what type of alternator you have please indicate it by selecting below.
Underdrive Power Pulleys
