The Lycoming IO-720

engine An engine or motor is a machine designed to convert one or more forms of energy into mechanical energy. Available energy sources include potential energy (e.g. energy of the Earth's gravitational field as exploited in hydroelectric power gen ...

is a large displacement,

horizontally opposed A flat engine is a piston engine where the cylinders are located on either side of a central crankshaft. Flat engines are also known as horizontally opposed engines, however this is distinct from the less common opposed-piston engine design, wh ...

, eight-cylinder aircraft engine featuring four cylinders per side, manufactured by

Lycoming Engines Lycoming Engines is a major American manufacturer of aircraft engines. With a factory in Williamsport, Pennsylvania, Lycoming produces a line of horizontally opposed, air-cooled, four, six and eight-cylinder engines including the only FAA-certi ...

. There is no carburated version of the engine, which would have been designated O-720 and therefore the base model is the IO-720. The IO-720 and the

Jabiru 5100 The Jabiru 5100 is a lightweight four-stroke horizontally opposed flat-eight air-cooled aircraft engine, manufactured by Jabiru Aircraft. Design and development The engine is direct-drive and is fitted with alternators, silencers, vacuum pump ...

are the only flat-eight configuration aircraft engines currently in production.

Design and development

The engine has a

fuel injection Fuel injection is the introduction of fuel in an internal combustion engine, most commonly automotive engines, by the means of an injector. This article focuses on fuel injection in reciprocating piston and Wankel rotary engines. All comp ...

system which schedules fuel flow proportionally to the airflow, with fuel vaporization occurring at the intake ports. The engine has a

displacement Displacement may refer to: Physical sciences Mathematics and Physics *Displacement (geometry), is the difference between the final and initial position of a point trajectory (for instance, the center of mass of a moving object). The actual path ...

of 722 cubic inches (11.8 litres) and produces . The cylinders have air-cooled

heads A head is the part of an organism which usually includes the ears, brain, forehead, cheeks, chin, eyes, nose, and mouth, each of which aid in various sensory functions such as sight, hearing, smell, and taste. Some very simple animals may no ...

cast from aluminum alloy with a fully machined combustion chamber. The first IO-720 was type certified on 25 October 1961 to the CAR 13 standard as amended to 15 June 1956 including 13-1, 13-2, 13-3, 13-4. In 2009 a new IO-720-A1B cost

US$ The United States dollar (symbol: $; code: USD; also abbreviated US$ or U.S. Dollar, to distinguish it from other dollar-denominated currencies; referred to as the dollar, U.S. dollar, American dollar, or colloquially buck) is the official ...

113,621, with a rebuilt engine retailing for US$75,435 and a factory overhaul priced at US$66,289.

Variants

;IO-720-A1A :Eight-cylinder, horizontally opposed, air-cooled direct drive, fuel injection, internal oil jet piston cooling, 722 cubic inches (11.8 litres), , certified 25 October 1961 ;IO-720-A1B :fuel-injected, 722 cubic inches (11.8 litres), , same as -A1A except equipped with Bendix S8LN-1208 and S8LN-1209 magnetos, certified 22 February 1971 ;IO-720-A1BD :fuel-injected, 722 cubic inches (11.8 litres), , same as -A1B except has a dual magneto, certified 30 December 1976 ;IO-720-B1A :fuel-injected, 722 cubic inches (11.8 litres), , same as -A1A except for top exhaust cylinders and offset exhaust valve shroud tubes, certified 4 November 1965 ;IO-720-B1B :fuel-injected, 722 cubic inches (11.8 litres), , same as -B1A except equipped with Bendix S8LN-1208 and S8LN-1209 magnetos and Bendix RSA-10ED1 fuel injection, certified 22 February 1971 ;IO-720-B1BD :fuel-injected, 722 cubic inches (11.8 litres), , same as -B1B except has a dual magneto, certified 30 December 1976 ;IO-720-C1B :fuel-injected, 722 cubic inches (11.8 litres), , same as -A1B except that it has up-exhaust cylinder heads, certified 22 December 1971 ;IO-720-C1BD :fuel-injected, 722 cubic inches (11.8 litres), , same as -C1B except has a dual magneto, certified 28 January 1977 ;IO-720-D1B :fuel-injected, 722 cubic inches (11.8 litres), , same as -A1B except has a rear type air inlet housing instead of a front inlet, certified 29 October 1973 ;IO-720-D1BD :fuel-injected, 722 cubic inches (11.8 litres), , same as -D1B except has a dual magneto, certified 28 January 1977 ;IO-720-D1C :fuel-injected, 722 cubic inches (11.8 litres), , same as -D1B except equipped with an angled fuel injector adapter, certified 15 April 1982 ;IO-720-D1CD :fuel-injected, 722 cubic inches (11.8 litres), , same as -D1C except has a dual magneto, certified 10 June 1977

Applications

;IO-720-A1A *

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- factory installation * Piper Comanche 400 - factory installation ;IO-720-A1B *

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- Johnson Aircraft conversion ;IO-720-A1BD *

Barr 6 The Barr 6, also called the Barr Six, Barr 06 and more recently the Morrison 6, is an American amateur-built aircraft that was initially produced by Barr Aircraft of Williamsport, Pennsylvania and now by Morrison Aircraft of Nambour, Queensla ...

;IO-720-B1A *

Northwest Ranger C-6 The Northwest Ranger was a Canadian bush aircraft that was under development by Northwest Industries (NWI) of Edmonton, Alberta between 1968-1972. The aircraft was a type certified design, and intended to be supplied as a complete ready-to-fly- ...

- factory installation ;IO-720-B1B *

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- MR. R.P.M. conversion ;IO-720-B1BD *

- MR. R.P.M. conversion ;IO-720-D1B *

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- factory installation ;IO-720-D1C *

- Johnson Aircraft conversion ;IO-720-D1CD *

- Johnson Aircraft conversion

Specifications (IO-720A)

References

{{Lycoming aeroengines 1960s aircraft piston engines IO-720

Design and development

Variants

Applications

Specifications (IO-720A)

See also

References