The Charomskiy M-40 was a Soviet turbocharged aircraft diesel engine developed during World War II.
It failed its State acceptance testing in May 1940, but production began regardless at the Kirov factory in Leningrad which built 58 engines in the first half of 1941.
[1] Delivery problems with the Mikulin AM-34FRNV forced the termination of the production of the Petlyakov Pe-8 for lack of suitable engines in 1940, but the M-40 was adapted for use on the Pe-8 in the spring of 1941.
However the M-40 tended to "cut out at high altitude because the manually controlled fuel feed depended on a certain engine speed being maintained and it could only be restarted at about 1,500 metres (4,900 ft)".
[3] A boosted version, the M-40F, was tested in the summer of 1940 and was approved for production the following November, although only a small batch was built in 1941.