converting a '91 force 9.9hp to a 15 hp

[acdc96]

I want to convert my 1991 force 9.9hp to a 15hp outboard. i know they use the same cowlings and lower unit. also, alot of the same engine parts.

what would i need or need to do to convert it?

 

[Frank Acampora]

Re: converting a '91 force 9.9hp to a 15 hp

A 15 horsepower long block complete with carburetor..

 

[jerryjerry05]

Re: converting a '91 force 9.9hp to a 15 hp

I think the pistons and block are the same(I think???)
I hear the only difference is the carb??
Not absolutly sure.
The stroke might be different.
Try the Mercury techs?

 

[Frank Acampora]

Re: converting a '91 force 9.9hp to a 15 hp

The blocks are the same. BUT: While the bore and stroke are the same, the porting and compression ratio is different. A simple carb change will add some horsepower but will not get the engine to 15.