The flat-plane crank (sometimes flatplane) is a type of

crankshaft A crankshaft is a mechanical component used in a piston engine to convert the reciprocating motion into rotational motion. The crankshaft is a rotating shaft containing one or more crankpins, that are driven by the pistons via the connecting ...

for use in

internal combustion engines An internal combustion engine (ICE or IC engine) is a heat engine in which the combustion of a fuel occurs with an oxidizer (usually air) in a combustion chamber that is an integral part of the working fluid flow circuit. In an internal combus ...

that has a 180 degree angle between

crank throw A crankshaft is a mechanical component used in a piston engine to convert the reciprocating motion into rotational motion. The crankshaft is a rotating shaft containing one or more crankpins, that are driven by the pistons via the connecting ro ...

Details

Flat-plane cranks are used in V-configuration engines, generally with eight cylinders. Cadillac introduced a V8 flat-plane crank engine in 1923. Engine movingparts

Inline-four 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 vast majority of automotive four-cylinder engines use a straight-four layout (with the ...

cylinder engines almost all use flat-plane cranks, and thus are not usually identified as such. However, there are a few exceptions with crossplane cranks. Flat plane crank

The flat-plane crankshaft is a design that is no longer used in most mass production V engines as it is more prone to vibration and is inherently much louder than a

crossplane The crossplane or cross-plane is a crankshaft design for piston engines with a 90° angle (phase in crank rotation) between the crank throws. The crossplane crankshaft is the most popular configuration used in V8 road cars. Aside from the V8 alre ...

crankshaft. However, due to its simpler construction requiring less counterweight, it is inherently lighter with a higher rev limit. For this reason, it remains useful in sports and racing cars. Flat-plane crankshafts are generally associated with European sports cars such as

Ferrari Ferrari S.p.A. (; ) is an Italian luxury sports car manufacturer based in Maranello, Italy. Founded by Enzo Ferrari (1898–1988) in 1939 from the Alfa Romeo racing division as ''Auto Avio Costruzioni'', the company built its first car in ...

and Lotus V8 engines, and cross-plane cranks with American manufacturers. There are some exceptions such as the Ferrari-designed crossplane crank V8 of the

Lancia Thema 8.32 The Lancia Thema (Type 834) is an executive car produced by the Italy, Italian automaker Lancia between 1984 and 1994, and one of four cars to share the Type Four platform alongside the Alfa Romeo 164, Fiat Croma and Saab 9000. The Thema was first ...

and the flat-plane crank Ford Mustang GT350. The 2023 model year

Chevrolet Corvette Z06 Chevrolet Corvette Z06 refers to different models of the Chevrolet Corvette: * Chevrolet Corvette (C2)#Z06, Chevrolet Corvette C2 Z06 (1963) * Chevrolet Corvette (C5)#Z06, Chevrolet Corvette C5 Z06 (2001-2004) * Chevrolet Corvette (C6)#Z06, Chevrole ...

will have the largest flat-plane V8 ever seen in production cars at 5.5 litres. The way in which a flat-plane works within a V8 engine is more like two in-line 4-cylinder engines mated together, with the firing order of each order being in a Right-Left-Right-Left-Right-Left-Right-Left pattern. Being in this in-line configuration allows for the engine to rev much faster, making it more suitable for racing engines.

References

{{Reflist Crankshafts