The Klimov VK-107 was a V-12 liquid-cooled piston aircraft engine used by Soviet aircraft during World War II.
The VK-107 was a brand-new design having little in common with its predecessors M-105 and VK-106. To achieve a greater power output, each cylinder now had four valves (two intake and two exhaust), crankshaft and camshafts were completely revised, and a new supercharger design was implemented. Although the engine could have been ready for production as early as 1942, Soviet factories lacked the capacity to produce a brand new design. Thus, less powerful VK-105PF and VK-105PF2 were built instead. However, the appearance of Luftwaffe Messerschmitt Bf 109G with Daimler-Benz DB 605 engine in 1943 created an urgent demand for a more powerful engine. VK-107A was put into production in 1944 and was used on Yak-9U fighters. The engine was not well liked by either pilots or mechanics -- it had a life expectancy of only 25 hours and war emergency power was almost never used for fear of decreasing this even more. The engine was also difficult to service, in part because its exhaust headers were on the inside of the cylinder banks, the reverse placement of most V-type liquid-cooled engine designs.