Converting OMC 9.9 to 15hp

[ruthherm]

What are the parts needed to convert OMC 9.9 to 15hp? Can I just rejet carb, and what problems has anyone encountered making this conversion?<br /><br />Thanks for responding.

 

[JB]

Re: Converting OMC 9.9 to 15hp

There are a number of changes required to convert, Herm. <br /><br />Bottom line? It isn't worth it. The actual difference in performance is trivial and the cost is more than a trade for a 15 would cost.<br /><br />Whatever you do, don't follow the wise guys who tell you to "just change the jets". You will end up with a lousy running, too rich 9.9.<br /><br />Good luck.

 

[Boatist]

Re: Converting OMC 9.9 to 15hp

JB is right it is more than jets. You at least have to change whole carb. 9.9 Throat is .625 and the 15 is .875. The jet are also bigger on the 15. Not sure about exhaust, but normally if want more power out of same block need to get more air and fuel in and also get more exhaust out. Good luck