fibreglass exhaust bends?

Discussion in 'Inboards' started by alibi, Dec 5, 2008.

  1. alibi
    Joined: Oct 2008
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    Location: New Zealand

    alibi Junior Member

    does anyone know how to make fibreglass exhaust bends? very familiar with composite, just need to know how to mold the bends properly:rolleyes:
  2. waikikin
    Joined: Jan 2006
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    Location: Australia

    waikikin Senior Member

    alibi, mold them thinly over a steel bend, then cut/split them off & then reassemble with your tubes etc for the exhaust & proceed with the rest of your laminate. All the best from Jeff
  3. Frosty

    Frosty Previous Member

    My 250Hp Engines have 5 inch soil pipe as exhausts,. It raises a few eyebrows when people see huge turbos blowing through PVC pipe.

    They have been on now 5 years,--not a problem. Of course water has to go through them.
  4. hmattos
    Joined: Jun 2004
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    Location: Devon UK

    hmattos Senior Member

    Here in devon - - we have made special exhausts and silencers for diesel boats. For simple shapes we mould on existing cylindrical drums etc, but to make a complex curve, just carve the shape out of polyurethane foam - from your builders merchant - and then lay up a few layers and scrape the foam out again when it is all dry.
    Remember to use a hi-temp resin and a good gelcoat to protect from the exhaust chemicals and heat. And again, you will have to have sme water cooling to keep the temps down and to silence better. Good luck
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    FAST FRED Senior Member

    The Vernalift folks make lift mufflers and elboes of Fire Retatdant GRP.

  6. MikeJohns
    Joined: Aug 2004
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    Location: Australia

    MikeJohns Senior Member

    You can get some very light wall PVC manufactured as downpiping for guttering systems with lots of bends and angles. This makes a good former for GRP that can be left in place after layup.

    When the plastic vetus mufflers came out they were greeted with a fair amount of derision in some circles; they have proven to be very reliable.

    As Frosty says you can use PVC plumbing pipe although it's better to use a layer of GRP over the final glued-up assembly with makes it much stronger for impact damage since the PVC is too brittle.

  7. Frosty

    Frosty Previous Member

    Bunnings Australia sell the different thickness wall pipes. the noise they make is not loud but a drone,--like a Lancaster bomber.

    I like it.

    I was of the same opinion that they would harden with the hot -warm water. They do not seem to have done so.
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