Continental O-300

The Continental O-300 and the C145 are a family of air-cooled flat-6 aircraft piston engines built by Teledyne Continental Motors.[1]

Rolls-Royce Continental O-300.JPG
Rolls-Royce Continental O-300 on display at the Solent Sky museum, England.
Type Piston aircraft engine
National origin United States
Manufacturer Continental Motors
Major applications Cessna 172
Cessna T-41 A Mescalero
Cessna 175 Skylark
Cessna 170
Maule M-4
Produced 1947-
Developed from Continental C-125

First produced in 1947, versions were still in production as of 2004. It was produced under licence in the United Kingdom by Rolls-Royce in the 1960s.


Continental O-300 engine installation in a Cessna 172

The C-145 was developed from the 125 hp (93 kW) C-125 engine. Both powerplants share the same crankcase, although the C-145 produces an additional 20 hp (15 kW) through a longer piston stroke, higher compression ratio of 7.0:1 and different carburetor jetting.[1]

The O-300 is a modernized C-145 and retains the same weight, dimensions, bore, stroke, compression ratio, displacement and output power of the earlier engine.[1]


The GO-300 employs a reduction gearbox, so that the engine turns at 3200 rpm to produce a propeller rpm of 2400. The GO-300 produces 175 hp (130 kW) whereas the ungeared O-300 produces 145 hp (108 kW).[1]

The GO-300 engine has a TBO (Time Between Overhaul) of 1200 hours, while 1800 hours is the standard for ungeared O-300 engines. The GO-300 engine suffered reliability problems as a result of pilots mishandling the engine and operating it at too low an engine rpm. This caused the Cessna Skylark to develop a poor reputation for engine reliability. Many Skylarks flying today have been converted to different, larger-displacement, direct-drive engines.[2]


Six-cylinder, 145 hp (108 kW), direct-drive engine.[1]
Modernized C145, 145 hp (108 kW), direct drive engine.[1]
Limited production for the Beagle B.218X twin that never went into production[3]
Geared O-300, 175 hp (130 kW) at 3200 crankshaft rpm, 2400 propeller rpm.[1]
Voyager 300
Liquid-cooled, fuel-injected version developing 170 hp (127 kW) at 2,700 rpm.
Rolls-Royce-Continental O-300
Licence production in the United Kingdom.


Cessna 175 showing the cowling bulge behind the propeller hub created by the GO-300 reduction gearbox



Voyager 300Edit

Specifications (O-300)Edit

Reference: Engines for Homebuilt Aircraft & Ultralights[1]

General characteristics

  • Type: 6-cylinder air-cooled horizontally opposed aircraft piston engine
  • Bore: 4 116 in (4.0625 in resp. 103.12 mm)
  • Stroke: 3 78 in (3.875 in resp. 98.425 mm)
  • Displacement: 301.4 in³ (4.94 L)
  • Length: 39.75 in (101.0 cm)
  • Width: 31.5 in (80.0 cm)
  • Height: 23.25 in (59.0 cm)
  • Dry weight: 268 lbs (121.5 kg) dry, without starter or generator


  • Cooling system: Air-cooled


See alsoEdit

Related lists


  1. ^ a b c d e f g h Christy, Joe: Engines for Homebuilt Aircraft & Ultralights, pages 60-63. TAB Books, 1983. ISBN 0-8306-2347-7
  2. ^ Perdue, Scott. "A Lark That Won't Quit". Retrieved 19 December 2008.
  3. ^ Flight Global, 21 March 1963, p. 399
  4. ^ Murphy, Daryl (2006). "The Cessnas that got away". Archived from the original on 27 February 2009. Retrieved 22 December 2008.