The Allison V-1710 aircraft engine designed and produced by the Allison Engine Company was the only US-developed V-12 liquid-cooled engine to see service during World War II. Versions with a turbocharger gave excellent performance at high altitude in the twin-engined Lockheed P-38 Lightning, and turbo-superchargers were fitted to experimental single-engined fighters with similar results.
The Wright R-3350 Duplex-Cyclone is an American twin-row, supercharged, air-cooled, radial aircraft engine with 18 cylinders displacing nearly 3,350 cubic inches (54.9 L). Power ranged from 2,200 to 3,700 hp, depending on model. Developed before World War II, the R-3350's design required a long time to mature, and was still experiencing problems with reliability when used to power the Boeing B-29 Superfortress.
The Pratt & Whitney R-4360 Wasp Major is an American 28-cylinder four-row radial piston aircraft engine designed and built during World War II. At 4,362.5 cu in (71.5 L), it is the largest-displacement aviation piston engine to be mass-produced in the United States, and at 4,300 hp (3,200 kW) the most powerful. First run in 1944, it was the last of the Pratt & Whitney Wasp family, and the culmination of its maker's piston engine technology.
The Daimler-Benz DB 601 was a German aircraft engine that was built during World War II. It was a liquid-cooled inverted V12, and powered the Messerschmitt Bf 109, Messerschmitt Bf 110, and many others. Approximately 19,000 601's were produced before it was replaced by the improved Daimler-Benz DB 605 in 1942.
The Junkers Jumo 213 was a World War II-era V-12 liquid-cooled aircraft engine, a development of Junkers Motoren's earlier design, the Jumo 211. The design added two features, a pressurized cooling system that required considerably less cooling fluid which allowed the engine to be built smaller and lighter, and a number of improvements that allowed it to run at higher RPM. These changes boosted power by over 500 hp and made the 213 one of the most sought-after Axis engine designs in the late-war era.
The Chrysler XIV-2220 was an experimental 2,500 hp, 2,220 cubic inch liquid-cooled inverted-V-16 World War II aircraft engine. Although several aircraft designs had considered using it, by the time it was ready for use in 1945 the war was already over. Only a few engines were built by Chrysler during a program that started in 1940, and it retained its 'X' designation the entire time as the XIV-2220, later XI-2220. The IV-2220 is historically important as it was Chrysler's first hemi, a design that would re-appear in 1950s Chrysler performance automobiles, make drag racing headlines in the 1960s, and continue into the 2000s.
The Daimler-Benz DB 603 was a German aircraft engine used during World War II. It was a liquid-cooled 12-cylinder inverted V12 enlargement of the 33.9 Liter DB 601, which was in itself a development of the DB 600. Production of the DB 603 commenced in May 1942, and with a 44.5 liter displacement, was the largest displacement inverted V12 aircraft engine to be used in front line aircraft of the Third Reich during World War II.
The Klimov M-105 was a V12 liquid-cooled piston aircraft engine used by Soviet aircraft during World War II.
The Klimov VK-106 was an experimental liquid-cooled V12 piston aircraft engine intended for Soviet aircraft during World War II.
The Klimov VK-107 was a V-12 liquid-cooled piston aircraft engine used by Soviet aircraft during World War II.
The Curtiss V-1570 Conqueror was a V12 liquid-cooled aircraft engine. Representing a more powerful version of the Curtiss D-12, the engine entered production in 1926 and flew in numerous aircraft.
The Delta was a 12-cylinder inverted-V aircraft engine built by Isotta Fraschini prior to and during World War II.
The Franklin O-335 was an American air-cooled aircraft engine of the 1940s. The engine was of six-cylinder, horizontally-opposed layout and displaced 335 cu in (5.5 L). The power output of later variants was 225 hp (168 kW).
The Argus 411 was an air-cooled, inverted-V12 aircraft engine developed by Argus Motoren in Germany during World War II.
The Rolls-Royce Pennine was a British 46-litre air-cooled sleeve valve engine with 24 cylinders arranged in an X formation. It was an enlarged version of the 22-litre Exe; a prototype engine was built and tested, but never flew. The project was terminated in 1945, being superseded by the jet engine.
The Rolls-Royce Exe, or Boreas, was a 24-cylinder air-cooled X block sleeve valve aircraft engine intended primarily for the new Fairey Fleet Air Arm aircraft, particularly the Fairey Barracuda. The Exe was relatively powerful for its era, producing about 1,100 hp (820 kW). This is notable given the relatively small 1,300 cubic inches (22 L) displacement, the Merlin requiring 1,600 cubic inches (27 L) for approximately the same power level. The X-24 layout made this quite a compact engine.
The Continental XI-1430 Hyper engine was a liquid-cooled aircraft engine developed in the United States by a partnership between the US Army Air Corps and Continental Motors. It was the "official" result of the USAAC's hyper engine efforts that started in 1932, but never entered widespread production as it was not better than other available engines when it finally matured. In 1939, the I-1430-3 was designated as the engine to power the Curtiss XP-55, an extremely radical pusher-engine fighter design that would not reach production.
The Shvetsov ASh-73 was an 18-cylinder, air-cooled, radial aircraft engine produced between 1947 and 1957 in the Soviet Union. It was primarily used as the powerplant for the Tupolev Tu-4 heavy bomber, an unlicensed, reverse engineered copy of the American Boeing B-29 Superfortress.
The Hispano-Suiza 12X was an aircraft piston engine designed in France by Hispano-Suiza during the early 1930s. A 12-cylinder Vee, liquid-cooled design, the 12X was used on several aircraft types, some of them being used in limited numbers during World War II. Due to the 12X's limited power output, its derivative the more powerful Hispano-Suiza 12Y had a longer career.
The SNECMA 14R was a 14-cylinder two-row air-cooled radial engine developed in France just prior to the start of World War II from the Gnome-Rhône 14N. The 14N radial engine was itself an improved version of the popular pre-war Gnome-Rhône 14K Mistral Major series; designed and manufactured by Gnome et Rhône, a major French aircraft engine manufacturer whose origins pre-date the First World War.
