Moteur avec cylindres en ligne

The straight engine (also called inline engine) is a piston engine where all of the cylinders are aligned in a row along the crankshaft. Most straight engines have four or six cylinders, however straight engines have ranged from two cylinders to fourteen cylinders. A straight engine is easier to build than an equivalent flat engine or V engine, since it uses one cylinder head rather than two. Inline engines are also narrower than flat engines or V engines, however they are longer and can be taller. The engine balance characteristics of a straight engine depend on the number of cylinders and the firing interval. When a straight engine is mounted at an angle from the vertical it is called a slant engine. Notable slant engines include the 1959-2000 Chrysler Slant-6 engine and the 1968-1981 Triumph Slant-4 engine. Some buses and diesel multiple unit trains take this concept further by mounting the engines horizontally (i.e. with a slant angle of 90 degrees). This is used to reduce the height of the engine, so that it can be located under the floor of the train or bus. Straight-twin engine Straight-three engine Straight-four engine Straight-five engine Straight-six engine Straight-seven engine Straight-eight engine Straight-nine engine Straight-twelve engine Straight-fourteen engine The straight-three and straight-four configurations are the most common layouts for three- and four-cylinder engines respectively. Straight-five engines are occasionally used, most recently by Audi and Volvo. Straight-six engines were common prior to the 1990s, however most six-cylinder engines now use a V6 layout. Similarly, straight-eight engines were popular in the 1920s to 1940s, however they were replaced by the more compact V8 layout. Many straight engines have been produced for aircraft, particularly from the early years of aviation and through the interwar period leading up to the Second World War. Straight engines were simpler and had low frontal area, reducing drag, and provided better cockpit visibility.