Help understanding

[lathehand]

I just bought a 1986 90hp inline 6 and it happend to have the original installation manual and it also covers the 75 and 115 hp engins.while looking at the prop slection I noticed the WOT on the 90 is only 4500-5000 rpm the others with the same prop and weight boat is 5000-5500 rpm.I did some online searching and discovered the only diffrences in the internal parts of this engins is the carb jets.Next I looked up in my sirvice manual and noticed there were diffrences in the timeing.Now with this being said if I were to rejet and retime my 90 I should be able to push it it up to 115 hp.Has anyone out there ever atempted this and what was the outcome.

[boats.net]

We don't attemp to alter horsepower on engines and not sure what the outcome would be.

[Faztbullet]

There more to it than that, the 115 block has a power port in cylinder wall and piston has power port hole, carbs are different in venturi size, the 90 has smaller exhaust ports, that why it develops it power in the lower rpm range. You cannont turn a 90 into a 115 without major machine work.....