Underdrive Power Pulleys have been around since the birth of hot rodding. By spinning the accessories slower, additional power is added back into the engine. Power Pulleys reduce the amount of power required to spin the accessories. It wasn't until the early-2000s that they were used in the BMW market. Rogue Engineering was at the forefront of BMW Power Pulley design and application, first testing them in racing environments and then releasing them for the street. Rogue E46 M3 Power Pulleys are designed to reduce power consumption while maintaining safety and efficiency in their respective accessories.
The Rogue Street Pulleys underdrive two systems on the S54 engine - water pump and power steering. There is enough of a safety margin available that Rogue can underdrive these systems safely and still return useable power and torque gains. Rogue pulleys are based off a calculated percentage from factory dimensions, so that particular component speeds are safely reduced without affecting their true purpose. Rogue believes a 2-pulley system is safest so their Street kit does not underdrive the alternator or crankshaft. A Race pulley set adds a crankshaft pulley and alternator pulley. This kit makes for the perfect blend of daily-driver smoothness with noticeably increased power that's always on tap. A new main drive belt is included.
Rogue Pulleys are CNC-machined from 6061-T6, heat-treated aluminum and specially coated with a military-spec MIL-A-8625 Type III hardcoat anodized finish. Hardcoat anodizing actually builds a small surface layer on top of the aluminum, preventing wear. The Rogue pulleys have been machined to be lighter than the stock pulleys, giving a small boost in throttle response as well!
E46 (99-05) > M3
E36/7 / E36/8 Z3 (96-02) > Z3 M - S54
E85 / E86 Z4 (03-08) > Z4 M