change 9.5 hp to 15 hp?

[Holy Mackinaw]

I have read somewhere on the internet about Johnson 9.5 hp. being change to 15 hp. by changing the carb and something else. which year engines does this apply to and is it the 9.5 or the 9.9? Also what exactly are the modifications that need to be done? I have been reading for a couple of weeks now on this site and this is my first post, any help is appreciated.

 

[Joe Reeves]

Re: change 9.5 hp to 15 hp?

The increase of horsepower, and the parts required, depends on which model you might have. What is the model number of that engine?

It does not apply to any of the 9.5hp models.

 

[Holy Mackinaw]

Re: change 9.5 hp to 15 hp?

yes, you are correct about the 9.9hp. I was looking for a 15 hp for my boat but there are not alot avail. in my area. but I am finding a lot of 9.9 avail. and was kicking around the idea of the conversion. from what I've read it seem it applies to late '70's and early 80's models. can any one confirm exactly what years it does apply to.

 

[Chinewalker]

Re: change 9.5 hp to 15 hp?

Any of the 9.9s from 1974 on up can be made into 15s, but some require more parts to convert than others... For some, it's as simple as a carb change. Others require changing out the exhaust tuner as well. Check the parts lists at the BRP site to confirm any given year's differences between the 9.9 and 15...
- Scott