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In automotive engineering, an engine is referred to as multi-valve (or multivalve) when each cylinder has more than two valves.

All poppet valve, four-stroke internal combustion engines have at least two valves per cylinder — one for intake of air and fuel, and another for exhaust of combustion products. Adding more valves improves the flow of intake and exhaust gases, potentially improving combustion efficiency, power, and performance. It is not practical to simply use two larger valves, for reasons of simple geometry (two smaller intake valves will fit side-by-side on one side of the combustion chamber, whereas a single one cannot be made much larger) and to keep the mass, and therefore inertia, of individual valves as low as possible. Many use double overhead camshafts (DOHC). 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 3.5L 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.

Volkswagen, Audi, Ferrari and Yamaha have introduced engines in the past that had a double overhead camshaft operating five valves per cylinder (three intakes, two exhaust). Toyota's 1991-98 4A-GE 1.6-liter 4-cylinder engine also uses five valves per cylinder and was co-designed by Yamaha as well.

Maserati made an experimental 2.0L turbo-V6 engine with six valves per cylinder 1985 (three intakes, three exhaust) ^[1].

Many engines were made with two valves per cylinder, but, starting in the late 80s, a virtual explosion of multi-valve and DOHC engines came to market. As a result, even the most basic engines today usually contain four valves per cylinder, though the two valve configuration is still popular.

Honda introduced the 4-valve XL250 SOHC single cylinder engine in 1972. In 1977 Honda introduced the 3-valve SOHC CB400 twin cylinder models. Yamaha introduced the 5-valve DOHC four cylinder FZ750 in 1984.

In the 1979 to 1992 era, Honda produced a limited number of racing and production motorcycles with 8-valve, V4 engines in 500 and 750cc displacements, the NR series.[[1]]

1. ^ Maserati's experimental 6-valve engine