Overhead camshaft engine

An overhead camshaft (OHC) engine is a piston engine in which the camshaft is located in the cylinder head above the combustion chamber. This contrasts with earlier overhead valve engines (OHV), where the camshaft is located below the combustion chamber in the engine block.

Single overhead camshaft (SOHC) engines have one camshaft per bank of cylinders. Dual overhead camshaft (DOHC, also known as "twin-cam") engines have two camshafts per bank. The first production car to use a DOHC engine was built in 1910. Use of DOHC engines slowly increased from the 1940s, leading to many automobiles by the early 2000s using DOHC engines.