Continental O-170

A65/O-170
	Continental O-170 on display at the Wings Over the Rockies Air and Space Museum
Type	Piston aero-engine
Manufacturer	Continental Motors

The Continental O-170 engine is the collective military designation for a family of small aircraft engines, known under the company designation of A50, A65, A75 and A80. The line was designed and built by Continental Motors commencing in the 1940s. It was employed as the powerplant for civil and military light aircraft.^[1]

The horizontally opposed, four-cylinder engines in this family are all identical in appearance, bore, stroke, dry weight, and piston displacement. All feature a bottom-mounted updraft carburetor fuel delivery system. The higher power variants differ only in compression ratio and maximum allowable rpm, plus minor modifications. The lower power versions are fully convertible to the higher rated versions.^[1]

Design and development

In all models of this family of engines the cylinder heads are of aluminum alloy, screwed and shrunk onto steel barrels. Spark plug inserts and intake valve seats are made from aluminum-bronze alloy, while the exhaust valve seats are steel. The engines all employ hydraulic tappets which operate in aluminum guides that are machined into the crankcase. The tappets are built from four parts, a cam follower body, cup, cylinder, and piston and operate with clearances of 0.03 in (1 mm) to 0.11 in (3 mm). The pushrods are steel and feature pressed-in ball ends.^[1]

Lubricating oil is delivered under pressure from the 4 US qt (3.79 L) oil sump to the drive bearings and the crankpins through the crankshaft. The cylinder walls and pistons are spray lubricated. Normal operating oil pressure is 35 psi, with minimum idle oil pressure 10 psi.^[1]

Variants

A50 on display at the Air Zoo

A50: 50 hp (37 kW), Compression ratio 5.4:1, max rpm 1,900, fuel consumption at cruise 3.8 US gph^[1]
A50-1
A50-2
A50-3
A50-4
A50-5
A50-6
A50-7
A65: 65 hp (48 kW), Compression ratio 6.3:1, max rpm 2,300, fuel consumption at cruise 4.4 US gph. The exhaust valves have stellite faces. The pistons have three rings, although some early production A65s had four piston rings.^[1]^[2]
A65-1
A65-2
A65-3
A65-4
A65-5
A65-6
A65-7
A65-8
A65-8F: A65-9:
A65-12
A75: 75 hp (56 kW), Compression ratio 6.3:1, max rpm 2,600, fuel consumption at cruise 4.8 US gph. The exhaust valves have stellite faces and the connecting rods have a 0.125 in (3 mm) hole drilled in the rod cap to improve lubrication. The pistons have three rings and smaller piston pins.^[1]^[2]
A75-1
A75-2
A75-3
A75-4
A75-5
A75-6
A75-14
A80: 80 hp (60 kW), Compression ratio 7.55:1, max rpm 2,700, fuel consumption at cruise 5.2 US gph. The connecting rods have a 0.125 in (3 mm) hole drilled in the rod cap to improve lubrication. The pistons have five rings and smaller piston pins.^[1]
A80-1
A80-2
A80-3
A80-4
A80-5
A80-6
A80-8
O-170: Military designation for the A50, A65, A75, A80 family of engines.
O-170-1
O-170-3
O-170-5
O-170-7

Applications

A50

A65

A Continental A65-8F installed in a Pietenpol Air Camper

A75

A80

Specifications (O-170-3 or A-65-8)

Data from Continental Aircraft Engine Operator's Manual^[2]

General characteristics

Type: 4-cylinder air-cooled horizontally opposed aircraft piston engine
Bore: 3.875 in (98 mm)
Stroke: 3.625 in (92 mm)
Displacement: 171 in³ (2.8 L)
Length: 31 in (787 mm)
Width: 31.5 in (800 mm)
Height: 29 5/16 in (745 mm)
Dry weight: 170 lb (77 kg)

Components

Valvetrain: One intake and one exhaust valve per cylinder, pushrod-actuated.
Fuel system: Updraft carburetor
Fuel type: 80/87 octane avgas
Oil system: Wet sump
Cooling system: Air-cooled

Performance

Power output: 65 hp (48 kW) at 2,300 rpm
Specific power: 0.38 hp/in³ (17.1 kW/L)
Compression ratio: 6.3:1
Fuel consumption: 4.4 US gal/hr
Oil consumption: maximum desirable 0.37 US quarts/hr
Power-to-weight ratio: 0.38 hp/lb (0.62 kW/kg)

Notes

^ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ ^j Christy (1983)
^ ^a ^b ^c Teledyne Continental Motors: Continental Aircraft Engine Operator's Manual, pages 4-5. Teledyne Continental Motors, FAA Approved December 1980. Continental Form No. X30012
^ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ ^j ^k ^l ^m ⁿ ^o ^p ^q ^r ^s ^t ^u ^v ^w ^x ^y ^z ^aa Wooden props (2008). "Fahlin Propellers". Archived from the original on 2013-12-28. Retrieved 2008-12-13.{{cite web}}: CS1 maint: bot: original URL status unknown (link)
^ Jackson (1974)
^ Plane & Pilot: 1978 Aircraft Directory, page 153. Werner & Werner, 1978. ISBN 0-918312-00-0

References

Christy, Joe: Engines for Homebuilt Aircraft & Ultralights, pages 43–52. TAB Books, 1983. ISBN 0-8306-2347-7
Donald, David (1995). American Warplanes of World War II. New York: Barnes & Noble Books. ISBN 0-7607-2274-9.
Jackson, A.J. (1974). British Civil Aircraft since 1919 Volume 3. London: Putnam. ISBN 0-370-10014-X.
Instruction Manual Continental Models A50, A65, A75 and A80 Aircraft Engines. Muskegon, Michigan: Continental Motors Corporation. 1944.

[Christy-1] ^ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ ^j Christy (1983)

[TCM1980-2] Teledyne Continental Motors: Continental Aircraft Engine Operator's Manual, pages 4-5. Teledyne Continental Motors, FAA Approved December 1980. Continental Form No. X30012

[Fahlin-3] ^ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ ^j ^k ^l ^m ⁿ ^o ^p ^q ^r ^s ^t ^u ^v ^w ^x ^y ^z ^aa Wooden props (2008). "Fahlin Propellers". Archived from the original on 2013-12-28. Retrieved 2008-12-13.{{cite web}}: CS1 maint: bot: original URL status unknown (link)

[Jackson_(1974)-4] Jackson (1974)

[P&P-5] Plane & Pilot: 1978 Aircraft Directory, page 153. Werner & Werner, 1978. ISBN 0-918312-00-0

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