An X engine is a

piston engine A reciprocating engine, more often known as a piston engine, is a heat engine that uses one or more Reciprocating motion, reciprocating pistons to convert high temperature and high pressure into a Circular motion, rotating motion. This article ...

with four banks of cylinders around a common

crankshaft A crankshaft is a mechanical component used in a reciprocating engine, piston engine to convert the reciprocating motion into rotational motion. The crankshaft is a rotating Shaft (mechanical engineering), shaft containing one or more crankpins, ...

, such that the cylinders form an "X" shape when viewed front-on. The advantage of an X engine is that it is shorter than a

V engine A V engine, sometimes called a Vee engine, is a common configuration for internal combustion engines. It consists of two cylinder banks—usually with the same number of cylinders in each bank—connected to a common crankshaft. These cylinder ...

of the same number of cylinders, however the drawbacks are greater weight and complexity as compared to a

radial engine The radial engine is a reciprocating engine, reciprocating type internal combustion engine, internal combustion engine configuration in which the cylinder (engine), cylinders "radiate" outward from a central crankcase like the spokes of a wheel. ...

. Therefore, the configuration has been rarely used. Several of the X engine designs were based on combining two

Examples

Four types of X engines are known to have reached production. In 1939–1942

Rolls-Royce Vulture The Rolls-Royce Vulture was a British Aircraft engine, aero engine developed shortly before World War II that was designed and built by Rolls-Royce Limited. The Vulture used the unusual "X-24 engine, X-24" configuration, whereby four cylinder ...

, a X-24 aircraft engine which was built using two Rolls-Royce Peregrine V12 engines. The Rolls-Royce Vulture was briefly used in the

Avro Manchester The Avro 679 Manchester was a British twin-engine heavy bomber developed and manufactured by the Avro aircraft company in the United Kingdom. While not being built in great numbers, it was the forerunner of the more famed and more successful ...

heavy bomber, before engine failures caused it to be replaced by the Avro Lancaster (powered by the Rolls-Royce Merlin

V12 engine A V12 engine is a twelve-Cylinder (engine), cylinder Internal combustion engine#Reciprocating engines, piston engine where two banks of six cylinders are arranged in a V engine, V configuration around a common crankshaft. V12 engines are more c ...

General Motors General Motors Company (GM) is an American Multinational corporation, multinational Automotive industry, automotive manufacturing company headquartered in Detroit, Michigan, United States. The company is most known for owning and manufacturing f ...

also produced X engines for US naval ships during the

Second World War World War II or the Second World War (1 September 1939 – 2 September 1945) was a World war, global conflict between two coalitions: the Allies of World War II, Allies and the Axis powers. World War II by country, Nearly all of the wo ...

. The 16-184 engine was installed in several hundred "subchaser" boats from 1941 onwards, where they were typically used in pairs. It was considered a successful design and a few have survived to the present day. From 1944 the similar 16-338 engine was produced for submarines, where four were used in each of the first four members of the USN Tang class. These proved unreliable in service and were subsequently replaced by three Fairbanks-Morse engines in each boat. The other production X engine is the ChTZ Uraltrac 12N360 X-12 engine, first produced in 2015, and used in the Russian Armata tank platform. Several prototype 24-cylinder X engines for military aircraft were developed during World War II, including the Daimler-Benz DB 604, Rolls-Royce Exe and Isotta Fraschini Zeta R.C. 24/60, along with the 16-cylinder Napier Cub. Other prototype X engines include a 1920s Ford X-8 automotive engine, which was investigated during the development process of the Ford Flathead V8 engine. During the 1960s, Honda is said to have experimented with an X-32 engine configuration for their Formula One racing efforts, but abandoned the design as being too complex and unreliable. From 2006 to 2010, the ''Revetec X4v1'' and ''Revetec x4v2'' X-4 experimental petrol engines were developed by an engine research company, followed in 2013 by the ''Revetec X4-D1'' experimental petrol engine.

References

{{Piston engine configurations Piston engine configurations Engines by cylinder layout

Examples

See also

References