The Mitsubishi Shinten (震天, Quaking Sky) was a two-row, 14-cylinder air-cooled radial engine built by the Mitsubishi Aircraft Company for the Imperial Japanese Army Air Service (IJAAS) and the Imperial Japanese Navy Air Service (IJNAS) in the early 1930s.
Initially the Ha6 was to be installed on the IJAAS Mitsubishi Ki-21 bomber aircraft, but it was decided to use a competing engine, the Nakajima Ha5 instead.
Furthermore, Mitsubishi was ordered to produce Nakajima's engine at its factory under license.
In order to beat the rival and also to develop a more powerful engine for the new Navy Attack Bomber that became the infamous Mitsubishi G6M Betty, the Shinten was developed into the Mitsubishi Kasei by increasing the bore from 140 mm (5.51 in) to 150 mm (5.91 in) which in turn brought the displacement to 42 L (2,600 cu in) and increased power to 1,500 hp (1,500 PS).
If a very minor change is made, suffix letters are added after the model number.