The P.11 was powered by a number of different radial engines, these included the Bristol Mercury IV S2 (normal: 525 horsepower , maximum: 575 hp) of the P.11a, the Gnome-Rhone 9Krsd (550 hp, max: 595 hp) of the P.11b, the Bristol Mercury V S2 (565 hp, max: 600 hp) or alternatively the Mercury VI S2 (590 hp, max: 630 hp) of the P.11c: and finally the Gnome-Rhone 9Krse (560 hp, max: 610 hp) of the P.11f, the ultimate version of the aircraft.