[timbo]

Ok here are the engines for each plane (gleaned from a web site and not double checked for accuracy)

P47 - Powerplant: 1× Pratt & Whitney R-2800-59 twin-row radial engine, 2,535 hp (1,890 kW)
Corsair - Powerplant: 1× Pratt & Whitney R-2800-18W radial engine, 2,100 hp (1,565 kW)
Hellcat - Powerplant: 1× Pratt & Whitney R-2800-10W "Double Wasp" two-row radial engine with a two-speed two-stage supercharger, 2,000 hp (1,500 kW)
Mustang - Powerplant: 1× Packard Merlin V-1650-7 liquid-cooled supercharged V-12, 1,695 hp (1,265 kW)

I would have though if it was just a power thing then both the Corsair and the Hellcat should have had 4 blade props. Was there some other reason?