Here is a link to the film used for pilot training for flying the F4U-1 Corsair from wing fold, start up, takeoff, climb, and landing. the narrator gives the Manifold Air Pressure, Propeller RPM, Radiator settings and altitudes that the supercharger shifts. At the normal rated power climb neutral blower is used, 43.5" MAP at 2550 RPM and shifts from neutral blower to low blower at "approximately" 8,000 feet. Viewing the film is free. In the past you had to use Real Player to view the film, but there are now new choices, I used WMP. Over the last few years I have watched the Hellcat, Thunderbolt, P-40, P-39 and P-38. This was the first reference I had seen to 44" (43.5" to be exact) up to 8,000 feet.
The film is using the F4U-1 with the framed canopy at a time frame when the six position national insignia was being used.
http://www.zenoswarbirdvideos.com/F4U.html