Lycoming O-320

Lycoming O -320 is the name of a piston aircraft engine of an engine family of the U.S. manufacturer Lycoming. All are assembled in modular form of air-cooled OHV 4- stroke boxer engines. The four cylinders have a bore of 130.2 mm and a stroke of 98.4 mm, respectively. The displacement is thus 5240 cm ³, corresponding to 320 inch ³, of which the name originates. The engine was first introduced in 1953 and is today (2011) in production. The other engines of the manufacturer with the same bore and stroke cylinders in the two-cylinder Lycoming O- 160 as well as the six-cylinder Lycoming O- 480th Depending on compression for their operation, fuel with 80/87 91/ 96 or 100/130 octane required.


The cylinder heads are made of aluminum and are shrunk and screwed to the steel cylinder. Each cylinder of the engine has an inlet and an outlet valve. The Auslassventilköpfe are armored with stellite. The valve seats are shrunk into the cylinder heads. The pistons are made of an aluminum alloy and feature two compression rings and one oil scraper ring. Forged steel connecting rods have the connecting rod copper - bronze bearing. Which also forged crankshaft consists of a chromium -nickel-molybdenum steel alloy. After processing all bearing surfaces are hardened by nitriding. The crankcase is a vertically divided light metal casting. The engine has a pressurized oil lubrication with wet sump. There are versions with two Einzelzündmagneten of Slick / Unison (now Champion ) or with a Doppelzündmagneten Bendix (formerly Scintilla, now TCM) in the series O -320 H " 76 series" (installed in Cessna 172 N). Standard available are a tachometer output, an electric starter and a generator or alternator.

In addition may be attached to the rear part of the engine, an output for an additional fuel as well as a vacuum pump.


  • O -320: Source engine, which was authorized on 28 July 1953. It is still in production and makes, depending on the model between 140 and 160 hp at 2700 min -1. It is very common and is used in a large number of aircraft types.
  • IO -320: Version with a multi- point fuel injection and a power 112-119 kW ( 150-160 hp ) at 2700 min -1. As LIO -320 available with reverse rotation. Deliveries began in 1961. The engine is still manufactured today. It was installed, for example, in the Piper PA-30
  • AIO -320: Same as IO -320, but has a suitable for aerobatics fuel system and dry sump lubrication circulation. It was produced in 1969-1977 and used among others in the Bölkow Bo 209C.
  • AEIO -320: Version with 112 to 119 kW at 2700 min -1, which has been produced since 1974. It also has a suitable for aerobatic fuel system, the original wet sump lubrication system was retained. Built it is in the American Champion 8KCAB and the Grob G 115 D-2.

Other manufacturers

The engine is offered by Lycoming and other manufacturers such as America's Aircraft Engines and Teledyne Mattituck for general aviation without approval.

Technical data ( AIO -320- A1A)

  • Bore: 130.2 mm
  • Stroke: 98.4 mm
  • Displacement: 5240 cm ³
  • Start and continuous power: 119 kW (160 hp ) at 2700 min-1
  • Compression ratio: 8.5:1
  • Weight: 138 kg
  • Length: 764 mm
  • Width: 819 mm
  • Height: 527 mm


  • Jane's all the world 's aircraft 1971/72