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 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 The engine configuration describes the fundamental operating principles by which internal combustion engines are categorized. Piston engines are often categorized by their cylinder layout, valves and camshafts. Wankel engines are often categoriz ...

. Cadillac introduced a V8 flat-plane crank engine in 1923. Engine movingparts

Inline-four 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 Lotus may refer to: Plants *Lotus (plant), various botanical taxa commonly known as lotus, particularly: ** ''Lotus'' (genus), a genus of terrestrial plants in the family Fabaceae **Lotus flower, a symbolically important aquatic Asian plant also ...

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 and the flat-plane crank Ford Mustang GT350. The 2023 model year Chevrolet Corvette Z06 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 Rev or Rév may refer to: Abbreviations Rev. * Rev., an abbreviation for revolution, as in Revolutions per minute * Rev., an abbreviation for the religious style The Reverend * Rev., the abbreviation for Runtime Revolution, a development environ ...

much faster, making it more suitable for racing engines.

References

{{Reflist Crankshafts