# Lycoming O-290

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.

## Variants
### Civil models
#### 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.

### Military models
#### O-290-1

    Identical to the O-290-B

#### O-290-3

    Identical to the O-290-C

#### O-290-11

    Identical to the O-290-D

## Applications

* Adkisson SJ-1 Head Skinner
* Aerocar
* Aero Commander 100
* Aquaflight Aqua I
* Aydlett A-1
* Boeing L-15 Scout
* Chrislea Super Ace
* Falconar F11 Sporty
* Firestone XR-9
* Flying K Sky Raider
* Grumman Kitten
* Isaacs Fury Mk II
* Mustang Aeronautics Midget Mustang
* Pazmany PL-1
* Pazmany PL-2
* Piper PA-12
* Piper PA-18 Super Cub
* Piper PA-20 Pacer
* Piper PA-22 TriPacer
* Rogers Sportaire
* Sea Teziutlán
* Seibel S-4
* Smyth Sidewinder
* Stolp Starduster
* Stout Skycar
* Thorp T-18
* Toyo T-T.10
* VanGrunsven RV-1
* Van Lith VI
* Van's Aircraft RV-3
* Warner Revolution II
* Warner Sportster
* Williams-Cangie WC-1 Sundancer

## Specifications (O-290-D2A)

Data from Operator's Manual, Textron Lycoming Aircraft Engines.

### General characteristics

* 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)

### Components

* Valvetrain: Pushrod-actuated valves
* Fuel system: Carburetor
* Cooling system: Air-cooled

### Performance

* Power output: 140 hp (104 kW) at 2,800 rpm
* Specific power: 0.48 hp/in$^3$ (22.2 kW/L)
* Compression ratio: 7.5:1