The was a two-row, 14-cylinder air-cooled radial engine built by Mitsubishi Heavy Industries and used in a variety of World War II Japanese aircraft, such as Mitsubishi J2M and Mitsubishi G4M. The Mitsubishi model designation for this engine was A10 while it was an experimental project, in service it was known as the MK4, and known as the Ha101 & Ha111 by the Army and Kasei by the Navy. According to unified designation code it was Ha-32 of the variants from 11 to 27. Design and development Although originally ordered by the Imperial Japanese Navy, the Kasei was based on the earlier Mitsubishi Shinten engine, itself based originally on the Mitsubishi Kinsei. Produced in a wide variety of models, the Kasei began with a rated power of , with a gradual evolution to in later wartime versions. Three variants were developed for the Japanese Navy starting in 1939. It was also later adopted by the Imperial Japanese Army as the Ha-101 engine. Unified code was Ha-32. Physically, the engine had a rather large diameter compared to the of the Nakajima Homare engine. Its size and weight meant it was a challenging engine to use on single engine fighters. Variants MK4A [Ha-32] 11 , 2450 rpm at takeoff , 2350 rpm at , 2350 rpm at MK4B [Ha-32] 12 - same as MK4A 11 MK4C [Ha-32] 13 - with extended propeller shaft , 2450 rpm at takeoff , 2350 rpm at , 2350 rpm at MK4D [Ha-32] 14 - with contra-rotating shafts MK4E [Ha-32] 15 - with improved altitude performance MK4P [Ha-32] 21 , 2600 rpm at takeoff , 2500 rpm at , 2500 rpm at MK4Q [Ha-32] 22 - same as MK4A 21 MK4R [Ha-32] 23 - Water-injection , 2600 rpm at takeoff , 2500 rpm at , 2500 rpm at MK4R-C [Ha-32] 23c - - Fitted with a turbo charger that allowed an output of to be maintained up to instead of only MK4S [Ha-32] 24 - Same power as the MK4P 21 with contra-rotating shafts MK4T [Ha-32] 25 - , MK4R [Ha-32] 26 , 2600 rpm at takeoff , 2500 rpm at , 2500 rpm at MK4U-4 [Ha-32] 26a - Mechanically driven 3-speed supercharger MK4V [Ha-32] 27 Applications Kawanishi E15K Kawanishi H8K Kawanishi N1K Mitsubishi G4M Mitsubishi J2M Mitsubishi Ki-21 Nakajima B6N Nakajima G5N Yokosuka P1Y Specifications (MK4V 27) See also References Notes Bibliography Matsuoka Hisamitsu, Nakanishi Masayoshi.