Straight-seven engine

A straight-seven engine or inline-seven engine is a straight engine with seven cylinders. It is more common in marine applications because these engines are usually based on a modular design, with individual heads per cylinder.

Straight-seven engine with firing order 1-3-5-7-2-4-6

Marine engines

Straight-seven engines produced for marine usage include:

• Wärtsilä-Sulzer RTA96-C two-stroke crosshead diesel engine^[1]
• Wärtsilä 32 trunk piston engines^[2]
• MAN Diesel IMO two-stroke crosshead diesel engine^[3]
• Burmeister & Wain 722VU37 two-stroke diesel engine (commenced 1937, used in the Danish Havmanden-class submarines
• Sulzer 7QD42 diesel engine (1939-1940, used in the Dutch O 21-class submarines).^[4]

Land use

The AGCO Sisu 98HD is a straight-seven diesel engine that was released in 2008.^[5] Intended for farming machinery, the engine shares various components with the company's straight-six engine.^[6]