The Lycoming IO-720 engine is a large displacement, horizontally opposed, eight-cylinder aircraft engine featuring four cylinders per side, manufactured by Lycoming Engines.
There is no carbureted version of the engine, which would have been designated O-720 and therefore the base model is the IO-720. The IO-720 is the only flat-eight configuration aircraft engine currently in production.
Design and development The engine has a fuel injection system which schedules fuel flow proportionally to the airflow, with fuel vaporization occurring at the intake ports. The engine has a displacement of 722 cubic inches (11.8 litres) and produces . The cylinders have air-cooled heads 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$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 Northwest Ranger - factory installation Piper Comanche 400 - factory installation
IO-720-A1B Beechcraft 80 - Excalibur and Queen Air conversions Helio Courier - Helio Courier H-800 factory installation Pacific Aerospace FU-24-954 Piper PA-36 Pawnee Brave - Johnson Aircraft conversion
IO-720-A1BD Barr 6
IO-720-B1A Northwest Ranger C-6 - factory installation
IO-720-B1B Aero Commander - MR. R.P.M. conversion
IO-720-B1BD Aero Commander - MR. R.P.M. conversion
IO-720-D1B Embraer EMB 202 Ipanema - factory installation
IO-720-D1C Piper PA-36 Pawnee Brave - Johnson Aircraft conversion
IO-720-D1CD Piper PA-36 Pawnee Brave - Johnson Aircraft conversion
Specifications (IO-720A)
See also Jabiru 5100
References