| In
            1938, Continental introduced the A50, an improved version of
            their ground-breaking A40 of 1931.  In early 1939, the A65
            introduced refinements that allowed increased horsepower for the
            same displacement. The military designation for the A65 was the O-170.  |  | 
              |  | 4-cylinder, horizontally-opposed, air-cooled
                piston engine |  |  | Displacement: 171 cubic inches (2.8 liters) |  |  | Bore x stroke: 3.875 x 3.625 inches |  |