A straight-12 engine or inline-12 engine is a twelve-cylinder piston engine with all twelve cylinders mounted in a straight line along the crankcase.

Land use

Due to the very long length of a straight-twelve engine, they are rarely used in automobiles. The first known example is a engine in the 1920 French ''Corona'' car; however it is not known if any were cars sold. Packard also experimented with an automobile powered by an inline 12 in 1929. The straight-12 has also been used for large military trucks.

Marine use

Some Russian firms built straight-12s for use in ships in the 1960s and 1970s. MAN Diesel & Turbo 12K98ME and 12S90ME-C and the

Wärtsilä-Sulzer RTA96-C The Wärtsilä RT-flex96C is a two-stroke turbocharged low-speed diesel engine designed by the Finnish manufacturer Wärtsilä. It is designed for large container ships that run on heavy fuel oil. Its largest 14-cylinder version is 13.5 meters ...

are examples of contemporary marine engines in L-12-cylinder configuration. These are popular for propulsion in container ships.

References

Piston engine configurations 12-cylinder engines 12 {{Mech-engineering-stub