The Kawasaki Ha40, also known as the Army Type 2 1,100 hp Liquid Cooled In-line and Ha-60, was a license-built Daimler-Benz DB 601Aa 12-cylinder liquid-cooled inverted-vee aircraft engine.

The Imperial Japanese Army Air Service (IJAAS) selected the engine to power its Kawasaki Ki-61 fighter.

The Kawasaki Ha40 and the Aichi Atsuta were based on the engine that powered Germany's Messerschmitt Bf 109 fighter.

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 rear engine was connected to the nose-mounted gearbox by a long drive shaft similar to the American Bell P-39 Airacobra.