The P.108 was equipped with four air-cooled 18-cylinder P.XII radial engines, which suffered from reliability problems, but produced 1,010 kW (1,350 hp) at 3,000 m (9,800 ft), with 1,120 kW (1,500 hp) at takeoff, and drove three-blade constant-speed Piaggio propellers. The P.XII was two Piaggio P.X engines in tandem, which were versions of the French Gnome-Rhône 9K "Mistral" made under license, themselves being license-built Bristol Jupiters. Alfa Romeo also lacked a powerful, modern engine, and its 1,010 kW (1,350 hp) AR.132s were two Bristol Mercurys in tandem.