The W670 is the aircraft version, 220hp. The R670 Ordinance Engine (tank) has domed pistons and is rated at 250hp.
The tank engine has many other common components (jugs, starter, some internals) that can be used in the aircraft version, but the "tank engine" cannot be installed on a certified aircraft.
The crankshaft splines are also different. We had a tank engine new in the crate that donated the starter for our PT17 Stearman biplane.
I seen one of these front mounted in a old pickup on YouTube somewhere definitely a cool engine especially the ones with high dome pistons
How does this compare to the Continental R975-C1 or -C4 9 cylinder radial gasoline engines with an output of 350 or 400 hp (261 or 298 kW) at 2,400 rpm that were used in Sherman tanks?