The Lycoming O-340 is a family of four-cylinder

horizontally opposed A flat engine is a piston engine where the cylinders are located on either side of a central crankshaft. Flat engines are also known as horizontally opposed engines, however this is distinct from the less common opposed-piston engine design, wh ...

carburetor A carburetor (also spelled carburettor) is a device used by an internal combustion engine to control and mix air and fuel entering the engine. The primary method of adding fuel to the intake air is through the venturi tube in the main meteri ...

-equipped aircraft engines, that was manufactured by

Lycoming Engines Lycoming Engines is a major American manufacturer of aircraft engines. With a factory in Williamsport, Pennsylvania, Lycoming produces a line of horizontally opposed, air-cooled, four, six and eight-cylinder engines including the only FAA-certi ...

in the mid-1950s.

Design and development

The O-340 was designed by Lycoming specifically for the TEMCO-Riley D-16A Twin Navion project. Jack Riley, the designer of that aircraft was interested in an upgraded version of the Lycoming O-320 that would produce more power to give the Twin Navion a better single-engine service ceiling. The Lycoming O-360 was still years away in development and so a modification of the O-320 was undertaken by Lycoming. The O-320 received longer cylinder barrels and a crankshaft with a longer stroke to increase displacement and different piston connecting rods. This increased the compression to 8.5:1 and boosted power output to over the O-320's . The engine was later used in a number of airplanes and helicopters and also in

amateur-built aircraft Homebuilt aircraft, also known as amateur-built aircraft or kit planes, are constructed by persons for whom this is not a professional activity. These aircraft may be constructed from "scratch", from plans, or from assembly kits.Armstrong, Kenn ...

designs. The O-340 family of engines covers a range from to . All have a

displacement Displacement may refer to: Physical sciences Mathematics and Physics *Displacement (geometry), is the difference between the final and initial position of a point trajectory (for instance, the center of mass of a moving object). The actual path ...

of 340.4 cubic inches (5.58 litres) and the cylinders have air-cooled

heads A head is the part of an organism which usually includes the ears, brain, forehead, cheeks, chin, eyes, nose, and mouth, each of which aid in various sensory functions such as sight, hearing, smell, and taste. Some very simple animals may no ...

. The O-340 series was

certified Certification is the provision by an independent body of written assurance (a certificate) that the product, service or system in question meets specific requirements. It is the formal attestation or confirmation of certain characteristics of a ...

under Type Certificate E-277 and first approved on 20 July 1954. The engines are approved for both tractor and pusher applications.

Variants

;O-340-A1A :Four-cylinder, horizontally opposed, 340.4 cubic inches (5.58 litres), at 2700, dry weight , Marvel-Schebler MA-4-5 carburetor, Scintilla S4LN-20 and S4LN-21 magneto. Minimum fuel grade 91/96

avgas Avgas (aviation gasoline, also known as aviation spirit in the UK) is an aviation fuel used in aircraft with spark-ignited internal combustion engines. ''Avgas'' is distinguished from conventional gasoline (petrol) used in motor vehicles, w ...

. Certified on 13 January 1955. ;O-340-A2A :Four-cylinder, horizontally opposed, 340.4 cubic inches (5.58 litres), at 2700, dry weight , Marvel-Schebler MA-4-5 carburetor, Scintilla S4LN-20 and S4LN-21 magneto. Minimum fuel grade 91/96

. Identical to the A1A but with no provision for a hydraulic propeller control. Certified on 16 November 1956. ;O-340-B1A :Four-cylinder, horizontally opposed, 340.4 cubic inches (5.58 litres), at 2700, dry weight , Marvel-Schebler MA-4-5 carburetor, Scintilla S4LN-20 and S4LN-21 magneto. Minimum fuel grade 80/87

. Identical to the A1A except with a reduced 7.15:1 compression ratio and 160 hp to run on 80/87 fuel. Certified on 20 July 1954. The O-340-B1A was originally certified as just the "O-340", but the designation was changed to "O-340-B1A" on 27 September 1956.

Applications

* Brantly B-2 and B-2A helicopter *

Cessna 170 The Cessna 170 is an American light, single-engined, general aviation aircraft produced by the Cessna Aircraft Company between 1948 and 1956. It is the predecessor of the Cessna 172, the most produced aircraft in history, which replaced ...

(modified under STC) *

Oakland Super V Oakland is the largest city and the county seat of Alameda County, California, United States. A major West Coast port, Oakland is the largest city in the East Bay region of the San Francisco Bay Area, the third largest city overall in the Bay A ...

Piper Apache The Piper PA-23, named Apache and later Aztec, is an American four- to six-seat twin-engined light aircraft aimed at the general-aviation market. The United States Navy and military forces in other countries also used it in small numbers. Origin ...

(modified under STC) * TEMCO-Riley D-16A Twin Navion

Specifications (O-340-A1A)

References

{{Lycoming aeroengines O-340 1950s aircraft piston engines

Design and development

Variants

Applications

Specifications (O-340-A1A)

See also

References