Lycoming R-680 Radial Engine

General characteristics

  • Type: Nine cylinder air-cooled radial
  • Bore: 4 58 in (117 mm)
  • Stroke: 4 12 in (114 mm)
  • Displacement: 680 in³ (11.15 litres)
  • Length: 37.5 in (953.1 mm)
  • Diameter: 43.5 in (1104 mm)
  • Dry weight: 515.46 lb (233.9 kg)


  • Valvetrain: One inlet and one exhaust valve per cylinder at 30 degrees.
  • Fuel system: single-barrel carburetor
  • Fuel type: 87 octane rating gasoline
  • Oil system: Full pressure type
  • Cooling system: Air-cooled



 The Lycoming R-680 is a nine-cylinder air-cooled radial engine, the first aero engine produced by Lycoming. The engine was produced in two types, the E and B series; both are essentially the same. The B4E was available in a trainer version with a front exhaust collector "ring" for use without cylinder air baffles.