Absolutely the best water pump ever produced for a BMW car. Stewart Components is the leading producer of water pumps for NASCAR, Ford and Chevy V-8 domestic racers, as well as many newer electric OEM applications from BMW and Mercedes. This unique pump solves many problems associated with the stock design and later aftermarket evolutions, and introduces impressive performance and durability features:

• 15% flow increase
• Twice as efficient as factory pump
• Stainless steel impeller
• Silicon Carbide and Sintered Carbon Graphite Seal
• Rebuildable

The initial plastic impeller pump design was lightweight and provided adequate flow for low RPM use, but eventually cracked. Later designs used a heavier metal impeller that proved to be very hard on the bearings in the unit. Stewart has used a proprietary impeller that reduces strain on the bearings and seals in the unit. This means greater life for the bearings. Additionally an oversized FAG bearing and high quality seal ensure long life.

The impeller design allows for more fluid to be pumped at any given rpm. At high RPM it eliminates cavitation of the pump completely which means more cooling for your car, eliminating completely the elevated temps seen by many on the track. Racers will be able to further underdrive this pump for even less less power loss.

Fits all E36 6 cylinder cars (1992-1999 323, 325, 328, and M3), E46 non-M cars (323, 325, 328, 330), and all Z3 and Z4 models.