15hp modifications

I have owned many OMC 15's, and I want to know what the tech guys have done that works on increasing speed for these motors? What Mods worked and what did not. I have two prefect powerheads and plan on making one into a little speed demon, that will break the hearts of a stock 25 or maybe even a 35.

Sounds like a fun project.

what the tech guys have done that works on increasing speed for these motors?​

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It all depends on the boat and hull type...to go fast in a 15HP you need to be light and spin RPM. HP/Torque means nothing if you cannot transfer it to the water.

Perhaps look at fitting a 30 HP carburetor on it.----That will make it go faster.

I'm running it on the Gheenoes and Riverhawk boats both the 15ft and 13ft models. we've seen speeds of, on average of 26 to 31 mph, but with some perts I think it will go faster.

I think epoxy in the right places to speed up fuel flow, boyesen reeds, a little more compression on the head and I might see 30 plus mph.

Sounds good, go do it and start a post about your results. I for one would be curious to know how that all works for you.

Compression increase good for couple of HP..on a 2 stroke outboard you got to have more air/fuel coming in intake. Thus bigger carb. Reeds add 1-2 HP as the flow a lil freer due to reed stops removed.. Need to get 3-5 HP for every 1MPH gain on 2 stroke. You need to open up the front,add some air and fuel, bump compression, square off the intake port and bevel runners,and et as much motor/boat out of water to reduce drag..Below is how ports should look..the corners were just squared to increase flow but intake timing stayed the same .You do not want to widen them.