The Hiro Type 91, (full designation Hiro Type 91 520 hp water-cooled W-12), was a 12-cylinder, water-cooled, W engine developed for aircraft use by the Imperial Japanese Navy in the mid-1930s.
Power was in the 450 kW (600 hp) range.
Its design was derived from the Napier Lion.
An enlarged more powerful engine, the Hiro Type 90 600 hp water-cooled W-12 had also been developed, producing 600 hp.
Related lists