Inline Straight 12 engine
A straight-12 engine or inline-12 engine is a twelve-cylinder internal combustion engine with all twelve cylinders mounted in a straight line along the crankcase.
A straight-12 is a very long engine, and therefore straight-12 engines are not common in automobiles, but it has been used for large military trucks. Also, some Russian firms built straight-12s for use in boats in the 1960s and 1970s.
The Wärtsilä-Sulzer RTA96-C is offered in 12-cylinder configuration