Franklin Families of
Horizontally-Opposed Aircraft Engines

			Website Designation
			Manufacturer's Designation
			[Year of First Certification or Test]
Bore	Stroke	Displacement/Cylinder
inches	inches	cubic inches	2 cylinders	4 cylinders	6 cylinders	8 cylinders	12 cylinders
3.625	3.625	37.41		O-150
				4AC-150
				[1938]
3.875	3.625	42.75		O-170
				4AC-171
				[1939]
4.000	3.500	43.98		O-175	O-265
				4AC-176	6AC-264
				[1940]	[1940]
4.250	3.500	49.65		O-200	O-300	O-400	O-595
				4AC-199	6AC-298	8AC-398	12AC-596
				[1941]	[1941]	[1941]	[1941]
4.375	3.500	52.62			O-315
					6AL-315
					[1944]
4.500	3.500	55.67	O-110	O-225	O-335
			2A4	4A4	6A4, 6V4
			[1945]	[1945]	[1945]
4.625	3.500	58.80	O-120	O-235	O-350
			2A-120	4A-235	6A-350
			[1971]	[1964]	[1964]
4.625	4.000	67.20			O-405	O-540	O-805
					6AC-403	8AC-538	12AC-806
					[1942]	[1942]	[1942]
4.750	4.000	70.88			O-425
					6V6
					[1944]
5.000	4.250	83.45			O-500
					6A8-215
					[1945]