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