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new F115 SHO numbers on 18 HPX


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OK so I was finally able to break in the new motor. I decided to go with the Merc Spitfire X7 21 pitch (4 blade). The boat simply jumps out of the water. Easily on plane with 2 boat lengths. Many people told me I would only pick up 6-7 MPH moving up from an F90. Here are the numbers: I was running a full tank of gas and 2 people with very little equipment. I also replaced the gauges with command links.

3500 RPM 29.2 MPH 3.9 GPH

4000 RPM 33.3 MPH 5.8 GPH

4500 RPM 37.6 MPH 7.6 GPH

5000 RPM 43.2 MPH 9.1 GPH

5500 RPM 48.4 MPH 11.1 GPH

The motor had more to give but I was reluctant to push her. I was in the final stages of the breakin. When I get the top speed numbers I will post.

As usual I received so much advice from people on this forum and I couldn't be happier. This forum is full of good people always willing to help. Thanks so much.

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I'd run the motor hard for the first 20 hours to make sure the rings seat. Check the oil level every trip until you hit the 20 hour change. Try not to idle a lot. Once I got past the 2 hour break in my first 20 hours was all above 4500 mostly. I don't know if the little sho has as much potential to make oil.

Great performance!

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Dino no need to arrive late.... You always have an invitation on her. After all most of my upgrades were your request. lol

Linesider thanks for that advice. I'm definitely gonna follow it. Are you coming to West Coast Mav tourney?


I'll leave 1/2 hour early, get into the bights on a shallow tide at the incoming, catch all the reds in my secret spots and wait for you....

don't worry, I'll leave a few for you :)

We can always put a tow rope on the Skinny mini and with all your power...you can tow her at 30 mph....:) :)


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  • 1 year later...

Intheslot12 , I see in your post that you said the motor still had more and that you would post your top end speeds when you get them. Did you get your max RPM up to the 6300 after testing or are you still at 5500 RPM ? I am very interested in this set up. I am 90% sure I am going to put a 115 SHO on my HPX .   Thanks for any performance updates.  Joe R 

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