According to RL data test :
Spitfire MK1 take off weight 6,050 lbs with CSP should climb at 6 1/4 lbs 2600 RPM with 2800-2900 ft/min up to 11 000 ft then climb rate decrase
Spit Mk1 with Merlin III but 100 Octan should have even better climb rate beacuse of higher RPMs limitation - 2850 instead 2600 RPMs during climb power settings.
Spitfire MK II at 6172 lb ( so heavier then SPitfire MK1) had little better climb rate then Spitfire MK1 but with higher power settings - +9 lbs at 2850 RPMs.
