The Lycoming IO-390 engine is a horizontally opposed, four-cylinder aircraft engine, manufactured by Lycoming Engines. There is no carburetted version of the engine, which would have been designated O-390 and therefore the base model is the IO-390.

Design and development

The engine was originally conceived in the 1970s as the IO-400-X, but the project was never pursued. The IO-390 family of engines, which Lycoming refers to as the IO-390-X, produce 200 hp to 215 hp. The IO-390 was developed from the similar IO-360 engine, to increase the O-360's cylinder bore. (Although the IO-390 cylinder assembly is not the same part number as the IO-580, the cylinder barrels of both have a 5.318 bore and 4.375 stroke dimension.) It features a tuned induction system, roller tappets and Slick Start ignition. The engine has a fuel injection system which meters fuel in proportion to the induction airflow with fuel vaporization taking place at the intake ports. The engine has a displacement of 390 cuin. The cylinders have air-cooled heads. The IO-390 was first introduced at AirVenture 2002. It has a factory recommended TBO of 2000 hours and requires a dynafocal engine mount. The IO-390 was initially marketed through Lycoming's custom engine subsidiary, Thunderbolt Engines, prior to the engine's certification and was at that time only available for installation on non-certified aircraft. The IO-390 was certified on 30 March 2009 to FAR 33. In January 2009 the base price of the IO-390-EXP version was USD$32,650.00. In November 2009 Lycoming announced that it had obtained an FAA Supplemental Type Certificate to replace the originally fitted Lycoming O-360 engines in the Mooney M20E, M20F and M20J with a new or remanufactured IO-390-A3A6 engine. Also on November 12, 2009 Commander Aircraft received an STC for its model 112B using the MTV-12-B/188-59b propeller.

Variants

IO-390 models

AEIO-390 models

Applications

Specifications (IO-390-A1A6)