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Repowering 238 Mako with LS3

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  • Repowering 238 Mako with LS3

    Ok guys looking of opinions. I'm starting a new thread since I was not able to edit the title of the old one. . You guys have convinced me going to outboards is a bad idea so I push forward with the rebuild as an inboard. Now I want to increase my cruising speed I'm not too worried about economy. Much of my cruising is in protected waters, St Mary's river system between Lake Superior and Lake Huron. Want to repower to an LS3 engine, 430 HP and the engine itself weights 418 pounds compared to a 5.7 liter that weights 888 pounds. I think I should get good cruising speed, top end and less stress on the hull with the engine lightened up significantly. I have not seen any word on this set up in a classic Mako but hey why not. Does anybody have any thoughts. I know its a lot of power for the boat but they put these things in 23 foot Mailbu ski boats. The retro on the boat will be outstanding as I have the time and desire to make it right. Please share comments.
    Last edited by Ken Beller; 04-26-2021, 08:47 AM.

  • #2
    Well at least no one objects. .


    • #3
      I'm not objecting...but how will the weight difference affect the boat?

      I know what 330 horses will do for my heavy ass 26' Shamrock, I can only imagine the issues you will have dialing in the prop on that set-up.

      1992 211 w/175 OptiMax
      Glen Campbell, Pa.


      • #4
        Although not a direct comparison with what you are doing on the Mako, a guy out of the marina that I use has a late 80's 24 foot Limestone. Last summer he replaced the original 5.7 small block and alpha drive with an LS and a Bravo 3 drive. The boat used to top out at just over 30mph now it does 58! I don't know any specifics on fuel use or how it rides but he is more than happy with the change.
        Toronto, Canada
        76 Mako 23


        • #5
          From the guy that put a LS1 in a 1994 Jeep Wrangler: Do it!!

          And let us know how it does!!