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

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]
GO-300
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]
Variants
- C145
 - Six-cylinder, 145 hp (108 kW), direct-drive engine.[1]
 - C145-2
 - O-300
 - Modernized C145, 145 hp (108 kW), direct drive engine.[1]
 - O-300-A
 - O-300-B
 - O-300-C
 - O-300-D
 - O-300-E
 - Limited production for the Beagle B.218X twin that never went into production[3]
 - GO-300
 - Geared O-300, 175 hp (130 kW) at 3200 crankshaft rpm, 2400 propeller rpm.[1]
 - GO-300-A
 - GO-300-C
 - GO-300-D
 - 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.
 
Applications

O-300
- Aeronca Sedan
 - Baumann Brigadier
 - Cessna 160 - intended for production model[4]
 - Cessna 170
 - Cessna 172 and T-41 Mescalero
 - Maule M-4
 - Meyers MAC-145
 - Taylorcraft 15
 - Temco TE-1A
 
GO-300
- Cessna 175
 - Goodyear GZ-19 and GZ-19A
 
Voyager 300
- Alexeev Strizh
 
Specifications (O-300)
Reference: Engines for Homebuilt Aircraft & Ultralights[1]
General characteristics
- Type: 6-cylinder air-cooled horizontally opposed aircraft piston engine
 - Bore: 4 1⁄16 in (4.0625 in resp. 103.12 mm)
 - Stroke: 3 7⁄8 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
 
Components
- Cooling system: Air-cooled
 
Performance
- Power output: 145 hp (108 kW) at 2,700 rpm
 - Specific power: 0.58 hp/in³ (26.5 kW/L)
 - Compression ratio: 7.0:1
 - Power-to-weight ratio: 0.54 hp/lb (0.89 kW/kg)
 
See also
Related lists
References
- 1 2 3 4 5 6 7 8 Christy, Joe: Engines for Homebuilt Aircraft & Ultralights, pages 60-63. TAB Books, 1983. ISBN 0-8306-2347-7
 - ↑ Perdue, Scott. "A Lark That Won't Quit". Archived from the original on 5 November 2015. Retrieved 19 December 2008.
 - ↑ Flight Global, 21 March 1963, p. 399
 - ↑ Murphy, Daryl (2006). "The Cessnas that got away". Archived from the original on 27 February 2009. Retrieved 22 December 2008.
 
