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  1. #1

    Default Drilling out the exhaust.

    I have a Mercury 115. How do I drill out the exhaust so it sounds louder while in the water and give the motor more power. I saw a guy on the river one day who said he had done this before. Just wondering if it is possible and how to do it.

  2. #2
    Moderator Bondo's Avatar
    Join Date
    Apr 2002
    The Mouth of the Chaumont River, Ny.

    Default Re: Drilling out the exhaust.

    Ayuh,... It Ain't that Simple, 'n this Ain't a Prop question....

    I'll ge this moved to the Mercury Outboard forum...
    Any Grease is Better,..... Than No Grease at All.......

  3. #3
    Fleet Admiral jerryjerry05's Avatar
    Join Date
    May 2008
    Sebastian Fl.

    Default Re: Drilling out the exhaust.

    Sounds like he was a pulling on your leg!!!The only way to get more power from drilling out anything is reboring the cylinders.Then u will only get maybe 5 hp more.
    Usually getting more power means a bigger motor.J

    Other websites are NOT the place to buy parts.They managed to screw up my last 4 orders.
    NO communication,NO follow through. Incompetent staff.Nuff said!

    Buy American made Cars and Trucks!!!Towing insurance for a boat,a GREAT thing.

    If you fix your problem,do the rest of the posters a favor and send in one more post telling who,what, how it was fixed.J

    88 Bayliner 21CC Twin 85hp Forces.

  4. #4
    Chief Petty Officer Droll's Avatar
    Join Date
    Jul 2003
    Elverum / Norway

    Default Re: Drilling out the exhaust.

    The only way drilling holes can provide more "power" are this one...

    This mod can give you a bit more power out of the hole IF you got the right boat/engine combo..

    Drilling the exhaust other ways will in most cases just make more noise and weaken your driveshaft housing ( leg ).

    Arne Kjetil
    My engines :
    Mercury TII, next project
    Johnson V4m-10s 90 hp 1964,from the prosess.
    Mercury L6 ,Rebuilding a Tower

  5. #5
    Vice Admiral
    Join Date
    Apr 2007
    Wright City, MO

    Default Re: Drilling out the exhaust.

    1st problem, noise ordinances, get loud, get noticed, get ticketed.

    2nd problem, IF, (notice that's big), IF, you did manage to get more air to flow, that would change the fuel/air mixture and melt pistons. It ain't so easy to jet an outboard, but it can be done, just be ready to rebuilt it if/when you smoke it til you get it right.

    The extreme low pressure area created behind the prop hub by forward movement in the water works VERY well in scavaging/pulling the exhaust out of the motor.

    It is VERY difficult to improve on Merc engineering, they have been doing this for quite a while.
    Last edited by CharlieB; February 20th, 2011 at 08:17 AM. Reason: spelling

  6. #6
    Supreme Mariner Silvertip's Avatar
    Join Date
    Sep 2003

    Default Re: Drilling out the exhaust.

    More noise does not make more power. It just makes for more annoyed folks on the water.

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