Welcome Guest - Sign Up today
Welcome Guest - Sign Up today
Store Links Mobile - Shop Now



Help Tip: If you have a question that has not been answered to your satisfaction in the archives, it is always best to start a new thread of your own. By starting your own thread, you will receive the maximum number of views by forum members.

Below are some additional forum policies in hopes of all iboats members will follow, Thank you.

1. Please do not reply to old topics or hijack existing topics. Old topics of a technical nature are like a library book, Please do not write in them.

2. Old topics should be considered archives and used for reference only. Please do not reply to them.

3. Do not take over someone else’s topic (aka hijack) with your own question, even if it is similar. If you have a question that has not been covered to your satisfaction in the archives, it is always best to start a new topic of your own.

4. If you have a question for the original poster (OP) and the topic is over 30 days old, send the OP a PM, he may not even visit the forums any longer, or may not notice your question in the old topic.

5. By starting your own topic, you will receive the maximum number of views by forum helpers that may not even notice your question when it’s posted at the end of someone else’s topic. And those answers will be specific to your particular issue.

6. Please do not post to topics that have been inactive for more than 3 months unless you are the original poster. We have very active forums and any topic that remains inactive for that long should be considered "dead". It is especially confusing when there is an entirely new question posted to an old topic.

7. Posting at the end of any topic is considered to be hijacking the original posters topic which in turn subjects the topic to be closed if it continues to happen thus not making it fair to the original poster in the future had for some reason he/she needed to return for additional information or provide an update of the problem solved which is always welcomed within a reasonable amount of time frame.

8. Please note that you should see a red banner pop up near the bottom of each inactive topic asking you not to reply to old topics. The Red banner will read: Please note this topic has been inactive for 90 days. For the best results, please start a new topic.

Thank you all in advance for doing your part in helping iboats run a smooth ship.

Additional forum rules linked below.
See more
See less

Drilling out the exhaust.

  • Filter
  • Time
  • Show
Clear All
new posts

  • 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
    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...


    • #3
      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

      Buy American made Cars and Trucks!!!Towing insurance for a boat,a GREAT thing.
      ​Tools to make my life easier: Battery tester, die grinder, temp.gun, compression tester, DVA meter.

      In Scenic , Beautiful San Sebastian by the sea Florida

      88 Bayliner 21CC 2001 Mercury 225 HP EFI


      • #4
        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
          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, 09:17 AM. Reason: spelling


          • #6
            Sign up today
            Re: Drilling out the exhaust.

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