Introduced in 1934, the W-670 was based on the A-70 of 1929 with the bore increased from 4.625 to 5.125 inches. Designated the R-670 by the U.S. military, this engine was also used in tanks (including the M3 Stuart).

models

• W-670: 220 hp (164 kw)

specifications

• 7-cylinder, radial, air-cooled, piston engine
• Displacement: 668 cubic inches (10.9 litres)
• Bore x stroke: 5.125 x 4.625 in
   

used by

• Fairchild PT-23 Cornell
• Stearman PT-17 Kaydet
• Waco UPF