The Lycoming O-540 is a family of air-cooled six-cylinder, horizontally opposed fixed-wing aircraft and helicopter engines of 541.5 cubic inch (8,874 cc) displacement, made by Lycoming Engines. The engine is a six-cylinder version of the four-cylinder Lycoming O-360.
Design and development
Generally these engines produce 230 to 350 horsepower. They are installed on a large number of different aircraft types. Their main competitive engine is the Continental IO-520 and IO-550 series.
The AEIO version was developed for high-performance competition aerobatics aircraft. Starting at 260 hp (190 kW), the power was then improved to 300 hp (220 kW). The AEIO-540 family has achieved tremendous results in competition aircraft such as the Extra 300, CAP 232, and Zivko Edge 540.
All engines have an additional prefix preceding the 540 to indicate the specific configuration of the engine. There are also numerous engine suffixes, denoting different accessories such as different manufacturers' carburetors, or different magnetos.
O-540Standard, direct-drive, normally aspirated
Opposed engine, equipped with a
carburetor.
IO-540Normally aspirated engine with fuel
Injection.
AEIO-540Normally aspirated engine with fuel injection and inverted lubrication for
Aerobatic use.
TIO-540Turbocharged and fuel-injected.
TEO-540Turbocharged with independent
Electronic sensors and fuel injection controls for each cylinder which manage detonation and exhaust gas temperature making the engine compatible with a range of fuel compositions producing up to 350 horsepower.
LTIO-540Left-hand (opposite-direction) rotation, turbocharged, fuel-injected; used as the right-hand engine on
Piper PA-31-325 Navajo C/Rs and
Piper PA-31-350 Chieftains to prevent
critical engine control issues. Also used for the left hand side of the Aerostar 700P.
IGO-540Gearbox at the front end of the crankshaft to drive the propeller fewer revolutions per minute than the engine, normally aspirated with fuel injection. Dry sump engine built specifically for the Aero Commander 560F.
TIGO-540Turbo-charged, injected and geared
IGSO-540Supercharger driven by the engine, gearbox to drive propeller, and fuel injection (up to 380hp).
VO-540Vertically mounted engine for use in a helicopter, normally aspirated and equipped with a carburetor.
IVO-540Normally aspirated engine with fuel injection, mounted vertically for use in a helicopter.
TVO-540Turbocharged engine equipped with a carburetor, mounted vertically for use in a helicopter.
TIVO-540Turbocharged engine with fuel injection, mounted vertically for use in a helicopter.
HIO-540Helicopter engine mounted horizontally as in fixed-wing aircraft, normally aspirated with fuel injection; not used in any fixed-wing aircraft.
TIO-541Same as a TIO-540, except the "1" indicates an integral accessory drive.
TIGO-541Same as a TIGO-540, except the "1" indicates an integral accessory drive.
Data from FAA Lycoming IO-540 Series Type Certificate. Retrieved: 1 September 2008.
Type: Six-cylinder air-cooled horizontally opposed engineBore: 5.125 in (130.2 mm)Stroke: 4.375 in (111.1 mm)Displacement: 541.5 in³ (8.9 L)Dry weight: 438 lb (199 kg)Valvetrain: Two overhead valves per cylinderFuel system: Fuel injectionFuel type: 100 octane rating gasolineCooling system: Air-cooledPower output: 300 hp (223 kW) at 2,700 rpm at sea levelSpecific power: 0.55 hp/in³ (25.14 kW/L)Compression ratio: 8.7:1Power-to-weight ratio: 0.68 hp/lb (1.12 kW/kg)