The Evo style engine: (popularly known as the Blockhead) is an air-cooled, 45 degree, V-twin. Harley Davidson manufactured this type and companies such as S&S still produce engines based on the design. The HD engine was made in the 1340cc (80 cubic inch) displacement for their Big Twin bikes, replacing the Shovelhead. Manufactured until 1999 when it was replaced by the Twin Cam.