NASM Japanese Engine Research
Page 3
by Robert Mawhinney
Published 11 Jan 2007; Revised 26 Aug 2026

 

Nakajima Homare 21 (NK9H) Army Type 4 1,850hp Radial (Ha 45)
Unified Type Ha45-12
18 Cylinder Radial on Kawanishi N1K2-Ja Shiden Kai George

Takeoff Rating = 2,000 hp (Metric), +500 Boost
Low Blower Rating = 1,900 hp (Metric) at 3,000 rpm and 1,800 meters, +300 boost
High Blower Rating = 1,700 hp (Metric) at 3,000 rpm and 6,400 meters, +300 boost
Two speed supercharger, water methanol injection
Diameter = 1.180 m
Dry Weight = 820 kg

The Homare needs little introduction. This engine and the Nakajima Sakae are two of Japans most recognized engines.

 

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