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Exhaust for ULS

in General Tech Discussion 6 years ago
Working on relocating muffler from top to behind the engine.

Found some cracks, hope you can see them on pictures below.

Trying to do better job at new location.

Looking for good installation practices - how many spring joins we need to have minimum 4 or 8?

Muffler needs to have Lord mounts or not.

Can I install flex joins right next to engine heads 2-3 inches away from outlets?
v7KCE5ZhQZa9u7sLxA4nsg.jpg (You do not have access to download this file.)
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fullsizeoutput_1529_2018-12-02.jpeg (You do not have access to download this file.)
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  • Re: Exhaust for ULS

    by » 6 years ago

    The final photo looks like someone already welded over a previous crack.
    The more flex you can build into the installation the better.
    It looks like the current mounting had no give at all.

    Keep in mind that if you ever want to install Exhaust Gas Temp Sensors you will need a few inches of solid pipe right near the head.

    Bill Hertzel
    Rotax 912is
    North Ridgeville, OH, USA
    Clicking the "Thank You" is Always Appreciated by Everyone.

    Thank you said by: Eugene Klimenko
      
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  • Re: Exhaust for ULS

    by » 6 years ago

    Here is a picture of Evectors exhaust pipe upgrade that allows flex.
    http://midwestsportplanes.com/wp-content/uploads/2013/02/Evektor-Exhaust-Tubes-With-EGT.jpg
    Thank you said by: Eugene Klimenko
      
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  • Re: Exhaust for ULS

    by » 6 years ago

    Thank you!

    I didn't know that flex piping is available.

    Learned something important today. I was told that muffler needs to be installed on engine as rigid as possible. No rubber mounts or springs! We want engine and muffler to vibrate as one unit together.

    I was told Rotax 914 is done this way. Hope this is correct.

    `
    IeHmzjrRDSgDql5zLLkWw.jpg (You do not have access to download this file.)
      
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  • Re: Exhaust for ULS

    by » 6 years ago

    The 914 is a low compression engine, a UL with a a turbo charger. Like Roger said part of the vibration problem is due to the ULS's high compression. Some have installed a spacer between the block and cylinders to drop compression a bit to help with the vibration. I had tried a stronger springs and ended up with a cracked up exhaust up system like yours. While helping a friend with a Evector airplane I noticed the flex on the down pipes, his whole system had fallen off in flight and they offered the upgrade pipe flex kit to deal with the vibration as shown in my last post.
    Thank you said by: Eugene Klimenko
      
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  • Re: Exhaust for ULS

    by » 6 years ago

    I am surprised that you have fractures directly next to a flex joint.
    That joint requires that it have Anti-Seize compound reapplied occasionally/as needed.
    The Copper Based Lubes are for higher temperatures than the Aluminum Based products.

    See LMM Section 05-20-00, Page 5.

    Bill Hertzel
    Rotax 912is
    North Ridgeville, OH, USA
    Clicking the "Thank You" is Always Appreciated by Everyone.

    Thank you said by: Eugene Klimenko
      
    Report
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