Number of cylinders: 24
Bore x Stroke: 5 x 5.5 in
Compression: 6.0
Supercharger Ratios: 5.5 / 7.3
Airscrew Reduction Gear Ratio: 0.35
Direction of rotation : left hand
Dry weight: 2450 lbs
Max takeoff power, +6 psi @ 3200 RPM ( 3 minutes or 1000 ft ):
1800 hp ( 162 gallons per hour at sea level )
Note: Ammendment list 10, from Nov. 1941, gives new takeoff rating of +9 psi and 3000 RPM.
Max climbing ( +6 psi @ 2850 RPM, 30 minute limit ):
1780 hp @ 4000 ft ( low gear ), 142.5 gallons / hr at sea level ( 1700 hp )
1660 hp @ 13500 ft ( high gear ), 134.5 gallons / hr at sea level ( 1455 hp )
Max cruising ( auto rich ), +5 psi @ 2600 RPM:
1480 hp @ sea level, 0.61 pint / bhp / hr ( low gear )
1290 hp @ sea level, 0.66 pint / bhp / hr ( high gear )
Max cruising ( auto lean), +2 psi @ 2600 RPM:
1130 hp @ sea level, 0.53 pint / bhp / hr ( low gear )
990 hp @ sea level, 0.58 pint / bhp / hr ( high gear )
Ignition timing ( fully advanced ):
Starboard magneto ( firing exhaust plugs ): 57 deg before TDC
Port magneto ( firing inlet plugs ): 50 deg before TDC
Ignition timing ( fully retarded ):
Starboard magneto: 22 deg BTDC
Port magneto: 15 deg BTDC
Valve timing ( 2 intake, 2 exhaust per cylinder ):
Inlet opens: 24 before TDC
Inlet closes: 60 after BDC
Exhaust opens: 64 before BDC
Exhaust closes: 20 after TDC