UUC Motorwerks

UDPE39

Underdrive Power Pulley Set - 1996-2003 BMW E39 530i/528i/525i models

Power Pulleys

Fits 1996-2003 BMW E39 5-series 530/528/525 models.
Lifetime warranty on pulleys. Belt is considered a consumable item and will need periodic replacement.
Pulleys underdrive water pump and power steering to reclaim up to 11hp, power you can really feel.
No negative effects on cooling system or steering feel.
Pulleys are 100% Made In USA from T-6061 aircraft-grade aluminum, anodized black for cosmetic surface protection.

When you bought your BMW, you paid for a lot of horses... but are some of them stuck in the corral? Take back that lost horsepower! A car's engine does many things other than just making the car move. Power is used to run the various accessories... things like the water pump, power steering pump, and alternator. All of these use horsepower, horsepower that is lost. Power that could be making the car faster. Each accessory uses rotary power - each accessory is turned to perform it's function, whether it's an electrical component (the alternator) or a fluid displacing component (the water pump and power steering pump). They all have a pulley which takes power from the crankshaft pulley via a belt. Some of the engine accessories take more power than they really need, dramatically affecting engine performance. Like an overprotective parent setting a curfew, there is a very big safety margin built into many systems of a BMW, especially in the accessories. Driving these accessories at higher rpm is a waste of energy, running it at a much higher rate than it needs to for optimum effectiveness. This is energy which could be put toward acceleration instead. An underdrive pulley is a replacement accessory pulley that bolts up the same as the original pulley, but has a different size (ratio) intended to free up lost horsepower. By increasing the diameter of each accessory pulley, the speed at which the accessories are turning relative to engine RPM decreases. Does this actually make horsepower? Underdriving the accessories does not add power to the engine, it frees up the power that is normally wasted on overdriven accessories. The larger pulley will drive the accessories slower thus reducing their parasitic horsepower loss, resulting in more power sent to the wheels. As an additional benefit, the reduction in wear (less usage) on the accessories due to the lower duty cycles can extend the life of these parts.

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