4 cylinder engine

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A straight-four engine (also called an inline-four) is a four-cylinder piston engine where cylinders are arranged in a line along a common crankshaft.The majority of automotive four-cylinder engines use a straight-four layout (with the exceptions of the flat-four engines produced by Subaru and Porsche) and the layout is also very common in motorcycles and other machinery. Therefore the term "four-cylinder engine" is usually synonymous with straight-four engines. When a straight-four engine is installed at an inclined angle (instead of with the cylinders oriented vertically), it is sometimes called a slant-four.