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Tech Tip #1: Water Pumps & Pulleys

Water Pumps

“In order to increase your cooling system’s performance you must maximize both the WATER flow and AIR flow.”

There are significant differences between a stock or OEM water pump, and Stewart Components water pumps. Most stock or OEM pumps are built to meet standard performance requirements at relatively low RPM. Stewart pumps are designed and manufactured specifically for high performance applications.

Every pump is designed to exacting tolerances for reliable, long-term performance that meets the requirements for your application.

In addition, all Stewart high-flow water pumps are designed to deliver maximum flow with minimum power consumption. Stewart high-flow water pumps deliver up to 180 GPM (gallons per minute) of coolant flow (at 8,000 RPM), yet consume just 2.26 horsepower (at 4,000 RPM)!


Using the proper pulley and drive system is critical to matching the water pump’s performance to your specific application.

Race applications require a maximum water pump speed of 7000 RPM.

Street applications, the water pump speed must at least match crankshaft RPM, to a maximum recommended 25% faster than crankshaft speed.

Stewart Components does NOT recommend the use of underdrive pulleys on any STREET application. Stewart high-flow water pumps only consume 2.26 horsepower at 4,000 RPM, so the actual savings in parasitic horsepower loss through the use of underdrive pulleys is minimal. In addition, a properly designed cooling system’s flow and efficiency are designed to operate at a given speed. In years of testing, Stewart has consistently proven that the engine will lose more horsepower due to higher operating temperatures than any possible gain from underdrive pulleys.