High Quality Content by WIKIPEDIA articles! The Continental R-670 (factory designation W-670) was a seven cylinder 4-cycle radial aircraft engine produced by Continental displacing 668 cubic inches and a dry weight of 465 lb (211 kg). Horsepower varied from 210 to 240 at 2200 rpm. This engine was used on many airplanes in the 1930s and 1940s. The R-670 was widely used in the PT-17 Stearman primary training aircraft of the U.S. military.