עוד רשימה :
However this is not always the case: Chevrolet recently showed a 3-valve version of its Generation IV V8 which uses pushrods to actuate forked rockers, and Cummins makes a 4-valve pushrod straight-6 diesel, the Cummins 600. Starting in 1922, many Bugatti engines used three valves per cylinder actuated by a single overhead camshaft (SOHC). Nissan has produced the 1988-96 KA24E engine with three valves per cylinder (two intakes, one exhaust) that are also actuated by single overhead camshaft. Mercedes and Ford are currently producing V6 and V8 engines using this configuration. Ford claims an 80% improvement in high rpm breathing without the added cost of a second camshaft per bank of cylinders. The Ford design uses one spark plug per cylinder located in the center, but the Mercedes design uses two spark plugs per cylinder located on opposite sides, leaving the center free to add a direct-to-cylinder fuel injector at a later date. Thus there are many considerations to deciding how many valves an engine should have besides just the added cost versus adding breathing capability.
Some versions of the Honda D-series 4 cylinder engines, and all J-series V6 engines, R-series 4 cylinder engines, and the Chrysler 3.5 L V6 engine actuate four valves per cylinder with a single overhead camshaft. The V12 engines of many World War II fighter aircraft also used a SOHC configuration with four valves for each cylinder.