![Boyesen WPK-38AB; Water Pump Cover & Impeller Kit Black](http://roco4x4.com/cdn/shop/files/8dc4c6eb-bc8e-49e9-9b41-54237961b443.c8b60ff828d042ae2a96cde9a2eae58a_de6884db-1eaa-4d3a-a998-229844be2929_986x700.jpg?v=1715314505)
![Boyesen WPK-38AB; Water Pump Cover & Impeller Kit Black](http://roco4x4.com/cdn/shop/files/8dc4c6eb-bc8e-49e9-9b41-54237961b443.c8b60ff828d042ae2a96cde9a2eae58a_de6884db-1eaa-4d3a-a998-229844be2929_986x700.jpg?v=1715314505)
Description
By casting a totally new water pump cover, Boyesen was able to maximize the flow through the unit. Boyesen�s design takes advantage of everything from Bernoulli�s Effect to biological studies. Unlike the stocker, Boyesen�s water inlet has an increasing diameter and artfully curved shape. This is a vast improvement over most stock inlets, which decrease in diameter as they near the impeller and have a 90-degree bend at the pump. Patented nautilus style impeller for hydrodynamic efficiency, reducing heat, gaining horsepower and extending engine life. Can reduce engine temperatures by as much as ten degrees . Fits: Yamaha YZ450F 2010-2013