The Fiat 804 was custom-built for the 1922 regulations

The Fiat 804 is a racing car designed to comply with the two-liter engine displacement limit imposed by the Grand Prix regulations in 1922. Engineer Giulio Cesare Cappa modified an existing block by removing two cylinders and shortening the piston stroke to reach an exact displacement of 1,991 cm3. This design allowed the 660 kg vehicle to reach a top speed of 170 km/h thanks to an engine developing 92 horsepower.