title: Franklin O-335
text: # Franklin O-335
  
  The Franklin O-335 (company designations variations on 6A and 6V) was an American air-cooled aircraft engine of the 1940s. The engine was of six-cylinder, horizontally-opposed layout and displaced 335 cu in (5.5 L). The power output of later variants was 225 hp (168 kW).
  
  ## Design and development
  
  These engines were commonly vertically mounted and used to power many early helicopters in the United States. They were closely related to the 2A4 and 4A4 2- and 4-cylinder engines. In various subtypes, the 6A4 remained in continuous production from 1945 to the time Franklin's United States operations ceased in 1975, with versions continuing in Polish production into the 1990s.
  
  In 1947 this engine was modified into a water-cooled version by the Tucker Car Corporation for use in the 1948 Tucker Sedan. Tucker liked the engine so much that he purchased the Aircooled Motors/Franklin Engine Company, and it remained under the ownership of the Tucker family until 1961.
  
  ## Variants
  
  ### O-335-1
  
      Military designation of vertical installation model for helicopters :175 hp (130 kW)
  
  ### O-335-3
  
      Similar to -1 but changes in starter installation
  
  ### O-335-5
  
      200 hp (149 kW)
  
  ### O-335-5B
  
      200 hp (149 kW)
  
  ### 6A-335
  
      180 hp (134 kW) at 2,800 rpm
  
  ### 6AL-335
  
      150 hp (112 kW) at 2,600 rpm
  
  ### 6A4-125
  
      125 hp (93 kW) at 2,200 rpm
  
  ### 6A4-130
  
      130 hp (97 kW) at 2,200 rpm
  
  ### 6A4-135
  
      135 hp (101 kW) at 2,450 rpm
  
  ### 6A4-140
  
      140 hp (104 kW) at 2,375 rpm
  
  ### 6A4-145
  
      145 hp (108 kW) at 2,600 rpm
  
  ### 6A4-150
  
      150 hp (112 kW) at 2,600 rpm
  
  ### 6A4-165
  
      165 hp (123 kW) at 2,800 rpm
  
  ### 6A4-200
  
      200 hp (149 kW) at 3,100 rpm
  
  ### 6AG-335
  
      220 hp (164 kW) at 3,400 rpm
  
  ### 6AG4-185
  
      185 hp (138 kW) at 3,100 rpm
  
  ### 6AGS-335
  
      260 hp (194 kW) at 3,400 rpm
  
  ### 6AS-335
  
      240 hp (179 kW) at 3,200 rpm
  
  ### 6V-335-B
  
      210 hp (157 kW) at 3,100 rpm
  
  ### 6V-335-A1A
  
      200 hp (149 kW) at 3,100 rpm
  
  ### 6V-335-A1B
  
      200 hp (149 kW) at 3,100 rpm
  
  ### 6V4-165
  
      165 hp (123 kW)
  
  ### 6V4-178-B32
  
      178 hp (133 kW) at 3,000 rpm
  
  ### 6V4-200-C32
  
      200 hp (149 kW) at 3,100 rpm
  
  ### 6VS-O-335
  
      225 hp (168 kW) at 3,200 rpm
  
  ## Applications
  
  * Aero-Flight Streak
  * Aeronca Sedan
  * Bartlett Zephyr
  * Bell 47
  * Bell H-13 Sioux
  * Bellanca Cruisair
  * Brantly B-1
  * Goodyear Duck
  * Hiller H-23 Raven
  * Hiller 360
  * Hirth Acrostar
  * HTM Skytrac
  * Maule M-5-220C Lunar Rocket
  * Republic RC-3 Seabee
  * Seibel S-4
  * Sikorsky S-52
  * Socata MS.894 Rallye Minerva
  * Stinson Voyager
  * Sznycer SG-VI
  * Taylorcraft 15
  * Temco TE-1B
  * Tucker (automobile)
  * Temco YT-35 Buckaroo
  
  ## Specifications (6AL-335 / 6A4-150-B3)
  
  Data from Wilkinson
  
  ### General characteristics
  
  * Type: 6-cylinder air-cooled horizontally opposed direct drive supercharged aircraft piston engine
  * Bore: 4.5 in (114.3 mm)
  * Stroke: 3.5 in (88.9 mm)
  * Displacement: 335 cu in (5.49 L)
  * Length: 37.4 in (950 mm)
  * Width: 30.8 in (780 mm)
  * Height: 21.6 in (550 mm)
  * Dry weight: 307 lb (139 kg)
  
  ### Components
  
  * Valvetrain: OHV, 1 x inlet valve, 1 x exhaust valve operated by pushrods
  * Supercharger: Mechanically driven supercharger
  * Fuel system: 1x Marvel-Schebler MA-3SPA updraught carburettor
  * Fuel type: 80 Octane gasoline
  * Oil system: 80 S.U. secs (15.6 cSt) grade pressure fed at 40 psi (3 bar), wet sump
  * Cooling system: Air-cooled
  * Delco-Remy direct cranking electric starter motor
  
  ### Performance
  
  * Power output:
  * (Take-off): 150 hp (110 kW) at 2,600 rpm
  * (Normal): 150 hp (110 kW) at 2,600 rpm at sea level
  * (Cruising): 112 hp (84 kW) at 2,350 rpm at sea level
  * Specific power: 0.45 hp/(cu in) (20.35 kW/L)
  * Compression ratio: 7:1
  * Specific fuel consumption: 0.51 lb/(hp h) (0.311 kg/(kW h) cruising, 4.5 US gal/(hp h)) cruising
  * Oil consumption: 0.01 lb/(hp h) (0.006 kg/(kW h)
  * Power-to-weight ratio: 0.488 hp/lb (0.8 kW/kg)
  * B.m.e.p.: 137 psi (945 kPa)
  