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.

The Liberty L-12 is an American water-cooled 45° V-12 aircraft engine displacing 1,649 cubic inches (27 L) and making 400 hp (300 kW) designed for a high power-to-weight ratio and ease of mass production. It saw wide use in aero applications, and, once marinized, in marine use both in racing and runabout boats.