The Franklin 4 (US military designations O-150, O-170, O-175, O-200, O-225 and O-235) was a series of air-cooled aircraft engines of flat-4 configuration produced in the 1930s and 40s. The 4AC was first run in 1938.
Applications
Aeronca 50 Chief
Aeronca Arrow
Culver Cadet
Falconar F11 Sporty
Fetterman Chickadee
Goodyear Duck
Interstate Cadet
Langley Twin
Payne MC-7
Piasecki PV-2
Piper Cub
Piper PA-7
Porterfield Collegiate
Rearwin Skyranger
Rose Parakeet
Sackett Jeanie
Stinson Voyager 10A
Stout Skycar II
Taylorcraft BF and L-2
Vought-Sikorsky VS-300
Specifications:
4A4
1938
ATC 239
75-100hp
4A4-75
1945
222.7ci
4A4-85
1945
222.7ci
4A4-95
1945
222.7ci
4A4-100
1945
222.7ci
4A-225
1945
222.7ci
4AC
4AC-150 / O-150
1938
ATC 194, 206, 221, 226
50-65hp
149.6ci
Designer: Carl T Doman
4AC-150-40 – 40 hp (30 kW) at 1,875 rpm
4AC-150-50 – 50 hp (37 kW) at 2,300 rpm
4AC-150-A – 60 hp (45 kW) at 2,400 rpm
4AC-171 / O-170
1939
60 hp (45 kW) at 2,350 rpm
171ci
4AC-176 / O-175
1940
65-94hp
175.9ci
4AC-176-B – 65 hp (48 kW) at 2,200 rpm
4AC-176-BA (O-175-1) – 65 hp (48 kW) at 2,300 rpm
4AC-176-BA2 / O-175-1
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 cs) 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/in³ (16.837 kW/l)
Compression ratio: 6:1
Specific fuel consumption: 0.49 lb/hp/hr (0.298 kg/kW/hr, 220 US.gal/hp/hr) cruising
Oil consumption: 0.003 lb/hp/hr (0.0018 kg/kW/hr, 1.4 US.gal/hp/hr) cruising
Power-to-weight ratio: 0.357 hp/lb (0.587kW/kg)
4AC-176-C – 75 hp (56 kW) at 2,500 rpm
4AC-176-D – 80 hp (60 kW) at 2,650 rpm
4AC-176-F – 80 hp (60 kW) at 2,500 rpm
4ACG-176 / O-175
4AC-199 / O-200
1941 TC 4AC
4-cylindr horizontally opposed air-cooled
80-113hp
198.6ci
4AC-199-B – 65 hp (48 kW) at 1,950 rpm
4AC-199-D – 85 hp (63 kW) at 2,500 rpm
4AC-199-E (O-200-1) – 90 hp (67 kW) at 2,500 rpm
4AC-199-H (O-200-5) – 113 hp (84 kW) at 3,500 rpm
4ACG-199 / O-200
4A-225 / O-225
1945
222.7ci
4AL-225 / O-225
4A-235 / O-235 / Sport 4
1964
116-130hp
235.2ci
PZL F 4A
All Aero 