Kawasaki Ha40

A new high-horsepower narrow-profile engine was required for the Kawasaki Ki-64 experimental fighter. The aircraft design called for a narrow-profile fuselage, and the solution that Kawasaki developed was the Ha-201 engine. Although similar to the Aichi Ha-70, where two Aichi Atsuta engines, mounted side-by-side behind the cockpit driving a single large propeller — an arrangement already used by the Daimler-Benz DB 606 that powered the Heinkel He 119 reconnaissance monoplane prototypes, and later inspired Japan's own Yokosuka R2Y reconnaissance aircraft from the seventh and eighth He 119 prototypes being sold to Japan in May 1940 — for the Japanese Ki-64, its own powerplant installation design called for the two Kawasaki Ha-40 engines to be separately mounted, one in the aircraft's nose, the other behind the cockpit.

The engines were connected to a common gearbox that was mounted in the nose. The rear engine was connected to the nose-mounted gearbox by a long drive shaft similar to the American Bell P-39 Airacobra. The gearbox did not combine the power output of the two engines. Instead, the rear engine drove the forward controllable-pitch propeller, while the front engine independently drove the rearward fixed-pitch propeller.[2]

• Type: Twelve-cylinder liquid-cooled supercharged 60° inverted Vee aircraft piston engine
• Bore: 150 mm (5.91 in)
• Stroke: 160 mm (6.30 in)
• Displacement: 33.93 L (2,070.5 in³)
• Length: 1,722 mm (68 in)
• Dry weight: 590 kg (1,320 lb)

• Valvetrain: Two intake and two sodium-cooled exhaust valves per cylinder actuated via a single overhead camshaft per cylinder block.
• Supercharger: Gear-driven single-speed centrifugal type supercharger[3])
• Fuel system: Direct fuel injection
• Oil system: Dry sump with one pressure and two scavenge pumps
• Cooling system: Liquid-cooled

• Power output:
  
• 865 kW (1,175 PS or 1,159 hp) at 2,500 rpm for takeoff
• 787 kW (1,070 PS or 1,050 hp) at 2,400 rpm at 3,700 m (12,140 ft)
• Specific power: 25.52 kW/L (0.56 hp/in³)
• Compression ratio: 6.9:1
• Specific fuel consumption: 270 g/(kW·h) (0.44 lb/(hp·h))
• Power-to-weight ratio: 1.47 kW/kg (0.89 hp/lb)

• Monogram Closeup 13. ISBN 0-914144-13-8.
• Francillon, R. J., Japanese Aircraft of the Pacific War, Putnam, London, 1970 SBN 370 00033 1
• Goodwin, Mike & Starkings, Peter (2017). Japanese Aero-Engines 1910-1945. Sandomierz, Poland: MMPBooks. ISBN 978-83-65281-32-6.