The Menasco 4 Pirate series were 4-cylinder, air-cooled, in-line, inverted, aero-engines, for use in light general and sport aircraft during the 1930s and 1940s. The Menasco engines were interesting in that they came in both normally aspirated and supercharged forms, with the supercharged models exhibiting superior performance at higher altitudes, with a relatively small increase in dimensions and weight. The supercharged models had the S suffix added to their designation to show supercharging.
Variants:
Menasco A-4 Pirate (also listed as Menasco 4A)
90hp
Menasco B-4 Pirate
95hp
Menasco C-4 Pirate (Military designation L-365)
125hp
compression ratio 5.8: 1, dry weight 300lbs
Menasco Pirate C-4S
150hp
Menasco D-4 Pirate
125hp, compression ratio 5.5: 1, dry weight 311lbs
Menasco D-4-87 Super Pirate
compression ratio 6: 1, dry weight 310lbs
Menasco M-50 Pirate
Applications:
Stearman-Hammond Y-1
Willoughby Delta 8
Specifications:
Menasco C4S Pirate
Type: 4-cylinder, air-cooled, in-line, inverted engine
Bore: 121 mm (4.75 in)
Stroke: 130 mm (5.125 in)
Displacement: 5.9 L (363 cu in)
Length: 1,206 mm (47.5 in)
Width: 449 mm (17.7 in)
Height: 724 mm (28.5 in)
Dry weight: 135 kg (299 lb)
Valvetrain: 1 inlet and 1 exhaust valve per cylinder
Fuel system: 1 Stromberg Carburetor
Fuel type: 73 octane
Cooling system: Air
Power output: 150 hp at 2,260 RPM max/112hp at 2,025 RPM cruise
Compression ratio: 5.5:1
Power-to-weight ratio: 0.37hp/lb at cruise
All Aero 