Menasco D4-87

Menasco Motors Corporation was founded by Albert Menasco in 1926.  At the request of the industry legend, John Northrop, Al Menasco developed the inverted inline 4-cylinder engine which was used in the 1929 Northrop Avion EX-1, the first of Northrop’s flying wings.  The inverted inline design offered many advantages for pilots and aircraft builders, including:

  • Streamlined/low drag installation
  • A high prop centerline, which allowed the swing of a large prop with shorter landing gear
  • Improved visibility for the pilot
  • Exhaust fumes directed away from the pilot
  • A low center of gravity
  • Ease of accessibility to the engine

The first inline Menasco engine, the four-cylinder A4, was certified in May 1930 followed a short time later by the six-cylinder inverted A6.

Claude Ryan was one of Menasco’s best customers.  Ryan used the engine first in his Sport Trainer, the Ryan ST/STA, and then in military derivatives such as the PT-16, PT-20 and STM between 1934 and 1941.

Engine NameMenasco D4-87
ManufacturerMenasco Motors Corp.
Date of Manufacture1941
Cylinder Configurationinverted inline
Number of Cylinders4
Bore (inches)4.75
Stroke (inches)5.125
Displacement (cubic inches)363
Dry Weight (lb)320
Horsepower125-134hp @ 2260 rpm
Compression Ratio6.0:1
Rated Speed2175 rpm