Gnome-Rhône 7K

The Gnome-Rhône 7K Titan Major was a seven-cylinder 370 hp (270 kW) air-cooled radial engine, that started life as an enlarged Gnome-Rhône 5K with two extra cylinders. The Gnome-Rhône 5K was itself a licensed version of the Bristol Titan. The 7K is very comparable to the Bristol Neptune seven-cylinder engine since they used the same technology.[1] The 7K was followed by the larger and more powerful nine-cylinder 550 hp (405 kW) Gnome-Rhône 9K Mistral. Gnome-Rhône later responded to the need for a more powerful engine by developing the 7K into a two-row version that became the Gnome-Rhône14K Mistral Major.

A Nationalist China Breda Ba.28, powered by a Piaggio-built Gnome-Rhône 7K
Type Radial engine
Manufacturer Gnome et Rhône


Licence production in Romania by Industria Aeronautică Română (IAR).


Specifications (7Kd)

Data from [2]

General characteristics

  • Type: Seven-cylinder air-cooled radial engine.
  • Bore: 146 mm (5.75 in)
  • Stroke: 165 mm (6.50 in)
  • Displacement: 19.3 l (1,180 cu in)
  • Length: 146 mm (5.75 in)
  • Diameter: 1,235 mm (48.62 in)
  • Dry weight: 270 kg (600 lb)


  • Valvetrain: Pushrod operated over-head valves, two per cylinder
  • Supercharger: (7Ksd - single speed centrifugal blower)
  • Fuel system: Carburetor
  • Fuel type: Gasoline
  • Cooling system: Air-cooled


  • Power output: 7Kd - 260 kW (350 hp) at 2,000 rpm at sea-level for take-off
    7Ksd - 272 kW (365 hp) at 2,000 rpm at 1,500 m (4,900 ft)
    7Ksd - 250 kW (340 hp) at 2,000 rpm at 4,000 m (13,000 ft)
  • Compression ratio: 5.5:1

See also

Related development

Comparable engines

Related lists



  1. Gunston 1989, p.74.
  2. Moteurs Gnome-Rhône series K (PDF) (in Spanish). Paris: Société Des Moteurs Gnome-Rhône. Retrieved 3 October 2014.


  • Gunston, Bill. World Encyclopedia of Aero Engines. Cambridge, England. Patrick Stephens Limited, 1989. ISBN 1-85260-163-9
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