03-09 YAMAHA YZ450F: Boyesen Supercooler Water Pump Kit (MAGNESIUM) Heat Is the #1 Enemy of 4-Stroke Engine Performance Boyesen SuperCooler Water Pump Cover and Impeller Kits are specifically designed to enhance the performance of your engine's cooling system. These high-flow, hydrodynamic water pump kits have been tested and designed to flow more coolant. By increasing the flow, the engine will run cooler at a more constant temperature. The Boyesen Supercooler can reduce engine temperatures by as much as ten degrees, as confirmed by tests at Team Kawasaki. How does the Supercooler achieve this? Hydrodynamics.