The Italian 1931 Schneider Trophy entrant, the Macchi M.C.72, required an engine of 2,300 horsepower (1,700 kW) with the capability of producing up to 2,800 horsepower (2,090 kW) while having a weight of not more than 840 kilograms (1,850 lb). The contract was awarded to Fiat, but their most powerful V engine to that date was the 1,000-horsepower (750 kW) 12-cylinder Fiat AS.5 that had also been used for Schneider Trophy racing.
The solution was to couple two AS.5 engines in tandem to produce a V-24 with each engine independently driving one of a pair of contra-rotating propellers through co-axial shafts. The rear engine drove the front propeller through a reduction gearbox, located between the two engines, up to a shaft that passed between the cylinder banks of the reverse-mounted forward engine. The latter's crankshaft drive faced rearwards and drove the rearmost propeller in a likewise manner, but instead via a hollow shaft through which the rear engine driveshaft passed. A large rear-mounted supercharger was used to boost the engine, with the fuel/air mixture being delivered to the cylinders through a manifold that was centrally mounted between the cylinder banks of both engines.