Article · Wikipedia archive · Last revised Jun 3, 2026

Straight-seven engine

A straight-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.

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Jun 3, 2026
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Straight-seven engine with firing order 1-3-5-7-2-4-6 source ↗

A straight-seven engine (also known as a 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.

Marine engines

Straight-seven engines produced for marine usage include:

  • Wärtsilä-Sulzer RTA96-C two-stroke crosshead diesel engine1
  • Wärtsilä 32 trunk piston engines2
  • MAN Diesel IMO two-stroke crosshead diesel engine3
  • 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
  • English Electric 7SKM diesel engine (used in some Port Jackson & Manly Steamship Company ferries)

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

References

References

  1. "Wärtsilä RT-flex 82T".
  2. "Wärtsilä 32".
  3. "MAN Diesel Marine Engine IMO Tier I Programme". Archived from the original on 2011-03-10. Retrieved 2011-03-07.
  4. Cummins, C. Lyle Jr. (2007). Diesels for the First Stealth Weapon. Carnot Press. p. 405,464. ISBN 978-0-917308-06-2.
  5. "7-Cylinder - AGCO Sisu Power". Archived from the original on 7 July 2011.
  6. "AGCO SISU POWER launched new innovative 7-cylinder 9,8 litre engine". 10 September 2008. Archived from the original on 4 March 2016.