Is my mercury 18XD prop or flywheel rated

[merc 18xd]

I got a mercury 18XD s/n 7220795 i beleive it's a 1984. I wonder if the horsepower is prop or flywheel rated. And if i use a 14" pitch prop will i gain some top end speed vs a 13".

 

[Laddies]

Re: Is my mercury 18XD prop or flywheel rated

prop rated, if the engine could turn more pitch maybe, but you will lose power