title: Franklin O-500
text: # Franklin O-500
  
  The Franklin O-500 (company designation 6AL-500 and 6A8-215) was an American air-cooled aircraft engine that first ran in the mid-1940s. The engine was of six-cylinder, horizontally-opposed layout and displaced 500 cu in (8 L). The power output was 215 hp (160 kW).
  
  ## Variants
  
  ### 6AL-500
  
      (alternative designation) 215 hp (160 kW) at 2,500 rpm, with crankcase/prop-shaft extension for pusher installation.
  
  ### 6A8-215-B8F
  
      215 hp (160 kW) at 2,500 rpm, with crankcase/prop-shaft extension for pusher installation.
  
  ### 6A8-215-B9F
  
      same as B8F but with different ignition components.
  
  ## Applications
  
  * Convair 106 Skycoach
  * Piaggio P.136
  * Republic RC-3 Seabee
  * Waco Aristocraft
  
  ## Specifications (6AL-500 / 6AB-215-B8F)
  
  Data from Aircraft engines of the World 1950.
  
  ### General characteristics
  
  * Type: 6-cylinder air-cooled horizontally opposed aircraft piston engine
  * Bore: 5 in (127.0 mm)
  * Stroke: 4.25 in (108.0 mm)
  * Displacement: 500.76 cu in (8.2 L)
  * Length: 66.3 in (168.4 cm)
  * Width: 33.9 in (86.1 cm)
  * Height: 27.4 in (69.6 cm)
  * Dry weight: 488 lb (221 kg)
  
  ### Components
  
  * Valvetrain: 1x OHV exhaust and inlet per cylinder operated by push-rods and rockers
  * Fuel system: 1x Marvel-Schebler MA4-5 updraught carburetor
  * Fuel type: 80 octane Gasoline
  * Oil system: Pressure feed at 35–45 psi (2.4–3.1 bar)
  * Cooling system: Air-cooled with cooling fan and shrouds
  
  ### Performance
  
  * Power output: 215 hp (160 kW) at 2,500 rpm
  * Specific power: 0.43 hp/cu in (19.6 kW/L)
  * B.m.e.p.: 136 psi (9.38 bar)
  * Compression ratio: 7:1
  * Specific fuel consumption: 0.5 lb/(hp⋅h) (0.30 kg/kWh)
  * Power-to-weight ratio: 0.44 hp/lb (0.72 kW/kg)
  