What is OHV, OHC and DOHC?

OHV (Over Head Valve): It is also called as Pushrod engine. In an OHV engine, the camshaft is placed inside the block and the valves are operated through lifters, pushrods and rocker arms. This mechanism is called a valvetrain. An OHV design has been successfully used for many years. Most early American cars had OHV engines and they are still used in trucks and sports cars.

OHC (Over Head Cam): It is also called as SOHC (Single Over Head Cam). In a SOHC engine the camshaft is installed in the cylinder head, and valves are operated either by the rocker arms or directly through the lifters.

DOHC (Double Over Head Cam): It is also called as Twin-Cam engine. The majority of modern cars have a DOHC engine. A typical DOHC engine has two camshafts and four valves per cylinder. One camshaft operates intake valves, while another camshaft controls exhaust valves on the opposite side.

Currently, the DOHC engine design is the most fuel-efficient, but an old-school OHV engine will last longer in similar conditions and is cheaper to maintain.