The Lycoming O-360 is a family of four-cylinder, horizontally opposed, air-cooled piston aircraft engines. The designation belongs to Lycoming's 360-cubic-inch class, widely used in general aviation. It should be distinguished from related fuel-injected and specialised 360-series engines, whose additional designation letters identify materially different configurations.[1]O-360 and associated models operator's manualLycoming · lycoming.com · Accessed 2026-09-13Open source details[2]360 SeriesLycoming · lycoming.com · Accessed 2026-09-13Open source details
Layout and operation
The engine drives the propeller directly and uses opposed cylinder banks on either side of the crankcase. Lycoming's operating manual describes the associated engine systems, including lubrication, ignition and induction. In carburetted O-360 configurations, fuel metering takes place through a carburettor, unlike the injection equipment fitted to related IO-360 models.[1]O-360 and associated models operator's manualLycoming · lycoming.com · Accessed 2026-09-13Open source details
Dual ignition uses magnetos, while the lubrication system is a pressure-fed wet-sump arrangement on the ordinary O-360 models covered by the manual. The manual separately describes exceptions among associated engine families. This makes the precise model important: features of an aerobatic or otherwise specialised derivative should not be assumed to apply to every 360-series engine.[1]O-360 and associated models operator's manualLycoming · lycoming.com · Accessed 2026-09-13Open source details
Family and ratings
Lycoming dates certified production of its broader 360-cubic-inch series to 1955 and describes an overall power range of 145–210 horsepower across that wider series. That range encompasses more than the basic O-360 designation. It is therefore inappropriate to assign the highest number to an arbitrary carburetted O-360 simply because the displacement is the same.[2]360 SeriesLycoming · lycoming.com · Accessed 2026-09-13Open source details
Example installation
The O-360-A4G provides a concrete example. Lycoming lists it at 180 horsepower for the Beech C-23 Sundowner, with a carburettor, a 12-volt electrical installation and specified magnetos and starter equipment. These details show how the full suffix connects the basic engine architecture with a particular aircraft installation and accessory arrangement.[3]O-360-A4GLycoming · lycoming.com · Accessed 2026-09-13Open source details
Lycoming's listing also specifies a dynafocal mounting arrangement for that model. Mounting, accessories and fuel-system components are part of the installation definition, so equal displacement and horsepower alone do not establish that two engines can replace one another without other changes.[3]O-360-A4GLycoming · lycoming.com · Accessed 2026-09-13Open source details
Support and documentation
Lycoming offers new, factory-rebuilt and overhauled engines and provides model-specific operating and parts documentation. The distinction between those products concerns the engine's condition and maintenance history, while the model designation concerns its configuration. Both are needed to describe an individual engine accurately; neither can be inferred from the short name O-360 by itself.[3]O-360-A4GLycoming · lycoming.com · Accessed 2026-09-13Open source details