ACL Race series performance bearings are for extreme endurance under harsh conditions. Plan on running high RPMs and big boost? Fatigue, stress wear, and failure are factors you won't have to worry about when you are running ACL's top of the line metallurgy.
ACL's main bearings are made of a softer metal so that you don't wear out your crank or engine block. Additionally, a thin layer of oil lubricates the connection between the bearings and the crank allowing the crank to "float" and reduce wear. Proper support via main bearings is crucial to prevent oscillations and wear that can damage the crankshaft and other components as the motor moves further out of balance.
Bearings with extra oil clearance will absorb the stress of higher horsepower motors greater, but will see increased wear during start up. We recommend these be purchased by experienced professionals only.