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