The Lycoming O-290 is a dual ignition, four-cylinder, air-cooled, horizontally opposed aircraft engine. It was first run in 1939, and entered production three years later.
A common variant of the type is the O-290-G, a single ignition model which was designed to drive a generator as part of a ground power unit.
O-290
Base model engine certified 27 July 1942. 125 hp (93 kW) at 2450 rpm, 6.25:1 compression ratio, dry weight 244 lb (111 kg)
O-290-A
Certified 27 July 1942. 125 hp (93 kW) at 2600 rpm continuous, 130 hp (97 kW) at 2800 rpm for 5 minutes, 6.5:1 compression ratio, dry weight 251 lb (114 kg) with SR4L-8 or N-8 magnetos, 245 lb (111 kg) with N-20 or N-21 magnetos.
O-290-AP
Certified 21 July 1944. 125 hp (93 kW) at 2600 rpm continuous, 130 hp (97 kW) at 2800 rpm for 5 minutes, 6.5:1 compression ratio, dry weight 251 lb (114 kg) with SR4L-8 or N-8 magnetos, 245 lb (111 kg) with N-20 or N-21 magnetos.
O-290-B
Certified 22 January 1943. 125 hp (93 kW) at 2600 rpm continuous, 130 hp (97 kW) at 2800 rpm for 5 minutes, 6.5:1 compression ratio, dry weight 247 lb (112 kg).
O-290-C
Certified 22 January 1943. 125 hp (93 kW) at 2600 rpm continuous, 130 hp (97 kW) at 2800 rpm for 5 minutes, 6.5:1 compression ratio, dry weight 238 lb (108 kg).
O-290-CP
Certified 21 July 1944. 125 hp (93 kW) at 2600 rpm continuous, 130 hp (97 kW) at 2800 rpm for 5 minutes, 6.5:1 compression ratio, dry weight 238 lb (108 kg).
O-290-D
Certified 13 December 1949. 125 hp (93 kW) at 2600 rpm continuous, 130 hp (97 kW) at 2800 rpm for 5 minutes, 6.5:1 compression ratio, dry weight 230 lb (104 kg).
O-290-D2
Certified 1 May 1952. 135 hp (101 kW) at 2600 rpm continuous, 140 hp (104 kW) at 2800 rpm for 5 minutes, 7.5:1 compression ratio, dry weight 233 lb (106 kg).
O-290-D2A
Certified 20 April 1953. 135 hp (101 kW) at 2600 rpm continuous, 140 hp (104 kW) at 2800 rpm for 5 minutes, 7.5:1 compression ratio, dry weight 236 lb (107 kg).
O-290-D2B
Certified 30 September 1954. 135 hp (101 kW) at 2600 rpm continuous, 140 hp (104 kW) at 2800 rpm for 5 minutes, 7.0:1 compression ratio, dry weight 236 lb (107 kg).
O-290-D2C
Certified 8 May 1961. 135 hp (101 kW) at 2600 rpm continuous, 140 hp (104 kW) at 2800 rpm for 5 minutes, 7.0:1 compression ratio, dry weight 235 lb (107 kg).
O-290-G
Non-certified, single ignition model intended for use driving a generator in a ground power unit, 125 hp (93 kW). Has been widely used in homebuilt aircraft, including the prototype Van's Aircraft RV-3.
O-290-1
Identical to the O-290-B
O-290-3
Identical to the O-290-C
XO-290-5
Provision for cylinder and oil cooling; for Firestone XR-9 helicopter
O-290-7
Provision for cylinder and oil cooling; for Firestone XR-9 helicopter
O-290-9
No.10 spline used on prop shaft
O-290-11
Identical to the O-290-D
Data from Operator's Manual, Textron Lycoming Aircraft Engines.
Type: 4-cylinder air-cooled horizontally opposed piston aircraft engine
Bore: 4.875 in (123.8 mm)
Stroke: 3.875 in (98.4 mm)
Displacement: 289 cu in (4.74 L)
Dry weight: 264 lb (119.7 kg)
Valvetrain: Pushrod-actuated valves
Fuel system: Carburetor
Cooling system: Air-cooled
Power output: 140 hp (104 kW) at 2,800 rpm
Specific power: 0.48 hp/in³ (22.2 kW/L)
Compression ratio: 7.5:1
