The Project Z (also called the Z Bombers Project) was a military project of the Empire of Japan, similar to the Nazi German Amerika Bomber project, to design an intercontinental bomber capable of reaching North America.
The planned aircraft
The Project Z plane was to have six engines of 5,000 horsepower each; the Nakajima Aircraft Company quickly began developing engines for the plane, and proposed doubling HA-44 engines (the most powerful engine available in Japan) into a 36-cylinder engine.
Designs were presented to the Imperial Japanese Army, including the Nakajima G10N, Kawasaki Ki-91, and Nakajima G5N. None, save for the G5N, developed beyond prototypes or wind tunnel models. Late in the war, the Z project and other heavy bomber projects were cancelled.
References
Project Z Wikipedia(Text) CC BY-SA