[Whacker]

Not in the F6F. According to this manual scan, 260 is the max. op temp for normal continuous, no limit. The F4U-1 variants list 260 max temp for military power operation, says 30 min max duration. The P-47D manual does say 232 is max continuous, 260 allowable for max 5 min.

Edit -

Bearcat manual also says 260 permissible for 1 hour, I know it's not in game though.

Edit 2 -

Looks like the two main differentiators are oil temp and MAP. In most of the cases, the settings between normal cont. and mil. power are minimal, but allow for higher MAP and max oil temp ranges. Oil temp makes the most sense to me, old WW2 era lube oil was pretty crappy and sludged up often, esp. under high temps.