The Potez 4D was a four-cylinder, inverted inline aircraft engine. It was first built shortly before World War II, but did not enter full production until 1949. Like the othe D-series engines, the cylinders had a bore of 125 mm (4.9 in) and a stroke of 120 mm (4.7 in). Power for different models was in the 100 kW-190 kW (140 hp-260 hp) range.