The Mitsubishi Shinten (震天) 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). The company model designation was A6(7) while it was an experimental engine project. Once accepted, it was known as the "Shinten" MK1 by IJNAS, and Ha-6 by the IJAAS.
A development of the Mitsubishi Kinsei engine, the stroke of the Kinsei was increased from 150 mm (5.91 in) to 160 mm (6.30 in) on the Shinten model 11 and to 170 mm (6.69 in) on the Shinten model 21 and 21Kai designs.
Lengthening the stroke increased the displacement from the Kinsei's 32.3 L (1,970 cu in) to 36.1 L (2,200 cu in) for the Shintin model 11. The increased displacement raised the horsepower from 1,070 hp (1,080 PS) to 1,200 hp (1,200 PS) at take-off power.
Initially Ha-6 Shintens were to be installed on Mitsubishi Ki-21 bomber aircraft, but it was decided to use a competing engine, the Nakajima Ha-5 instead. Furthermore Mitsubishi was ordered to produce Nakajima's engine at its factory under license. So only 113 Shinten engines were made and they were installed on only few types of aircraft.
In order to beat the rival and also to develop a more powerful engine for the new Navy Attack Bomber that became famous Mitsubishi G6M Betty, Mitsubishi 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).
Shinten 21 A6
Shinten 21kai A6