Based on the all new Boss 302 block from Ford Racing Performance Parts the Boss 331 crate engine is sure to be popular. It has a 4.25 bore and a 3.1 stroke length. The engine has outstanding breathing characteristics because of the CNC ported "Z" cylinder heads. A Ford Racing solid-lifter camshaft operates the valve train. The Boss Cleveland style valve covers give the engine a vintage racing look. Ford says the new engine is good for 500 horsepower @ 7200 rpm while developing 400 ft/lbs @5000 rpm.