Overhead valve engine

In 1896, U.S. patent 563,140 was taken out by William F. Davis for an OHV engine with liquid coolant used to cool the cylinder head,[5][6] but no working model was built.

In 1898, bicycle manufacturer Walter Lorenzo Marr in the United States built a motorised tricycle powered by a single-cylinder OHV engine.

[8] This engine employed pushrod-actuated rocker arms, which in turn opened poppet valves parallel to the pistons.

The first overhead camshaft (OHC) engine dates back to 1902, in the Marr;[13] however, use of this design was mostly limited to high-performance cars for many decades.

[14] At the 1994 Indianapolis 500 motor race, Team Penske entered a car powered by the custom-built Mercedes-Benz 500I pushrod engine.

In the early 21st century, several pushrod V8 engines from General Motors and Chrysler used cylinder deactivation to reduce fuel consumption and exhaust emissions.