The Franklin 4 (US military designations O-150, O-170, O-175, and O-200) was a series of air-cooled aircraft engines of flat-4 configuration produced in the 1930s and 1940s.
Data from:
4A4-75
4A4-85
4A4-95
4A4-100
4AC
4AC-150
(O-150)
4AC-171
60 hp (45 kW) at 2,350 rpm - (O-170)
4AC-176
(O-175)
4ACG-176
(O-175)
4AC-199
(O-200)
4ACG-199
O-200
4A-225
O-225
4AL-225
O-225
4A-235
O-235
Sport 4
O-235
O-150
military designation
O-170
military designation
O-175
military designation
O-200
military designation
O-225
military designation
O-235
military designation
(4AC-176-BA3 identical except for electric starter and generator)
Data from
Type: 4-cylinder air-cooled horizontally opposed aircraft piston engine
Bore: 4 in (102 mm)
Stroke: 3.5 in (89 mm)
Displacement: 176 cu in (2.88 l)
Length: 28.6 in (726 mm)
Width: 30.2 in (767 mm)
Height: 20 in (508 mm)
Dry weight: 182 lb (82.6 kg)
Valvetrain: OHV, 1x inlet valve, 1x exhaust valve operated by pushrods
Fuel system: 1x Marvel-Schebler MA-3P updraught carburettor
Fuel type: 73 Octane gasoline
Oil system: 40 S.U. secs (4.3 cSt) grade pressure fed at 40 psi (275,790 Pa), wet sump
Cooling system: Air-cooled
Power output: 65 hp (48.5 kW) at 2,300 rpm for take-off
Specific power: 0.37 hp/(cu in) (16.837 kW/L)
Compression ratio: 6:1
Specific fuel consumption: 0.49 lb/(hp h) (0.298 kg/(kW h), 220 US gal/(hp h)) cruising
Oil consumption: 0.003 lb/(hp h) (0.0018 kg/(kW h), 1.4 US gal/(hp h)) cruising
Power-to-weight ratio: 0.357 hp/lb (0.587kW/kg)
