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Thread: Muffler flame cone removal. C-180, Pponk

  1. #1

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    Muffler flame cone removal. C-180, Pponk

    I have a Knisely muffler. 3 years old, about 250 hours.

    The flame cones are showing some warping, as viewed through the tailpipe. I've been told there is approval to remove the cones; as long as you have the external carb heat muff, which I do.

    Does anyone know the reference for the flame cone removal approval(service letter, bulletin..)?
    Can someone share their experience with this muffler configuration?

    -Performance gain?
    -Oil/cyl temp reduction in the summer, on floats?
    -Cabin heat loss in the winter(avg temp here in winter is about 20F, but we do fly high on long trips, up there at 9-10k it can be down around 0F.) We do have backseaters normally.

    Another option is an Acorn muffler, STC'd without the flame cones.

    Thanks,
    Aqua

  2. #2
    jgerard's Avatar
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    On the big continentals I have no experience but for the small lycomings it seems to be an improvement

    Not sure about approval but that is how mine was repaired and yellow tagged many years ago before I bought my cub. No loss of anything from what I can tell. IT's plenty hot for cabin heat. Could have a slight improvement in static RPM. You would have the same thing as an Atlee turbo muffler but without the 3" tailpipe. I can tell you that I do have a different and louder pop sound to my exhaust note than a stock muffler does on a 150hp cub. That could just be the way an 135hp lyc sounds though.

    Jason
    Last edited by jgerard; 04-17-2013 at 05:48 PM.

  3. #3

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    Quote Originally Posted by aqua View Post
    I have a Knisely muffler. 3 years old, about 250 hours.

    The flame cones are showing some warping, as viewed through the tailpipe. I've been told there is approval to remove the cones; as long as you have the external carb heat muff, which I do.

    Does anyone know the reference for the flame cone removal approval(service letter, bulletin..)?
    Can someone share their experience with this muffler configuration?

    -Performance gain?
    -Oil/cyl temp reduction in the summer, on floats?
    -Cabin heat loss in the winter(avg temp here in winter is about 20F, but we do fly high on long trips, up there at 9-10k it can be down around 0F.) We do have backseaters normally.

    Another option is an Acorn muffler, STC'd without the flame cones.

    Thanks,
    Aqua
    As I prep for our PPonk 470-50 install this fall, I'm considering an Acorn exhaust to help with lowering CHT's and perhaps gain a bit of HP.
    Anyone want to chime in with their recommendations/thoughts/warnings?
    Definitely do the flame cone delete via Acorn's STC?

    Or, you can answer here, which might be better for filing & search purposes down the road.
    http://www.supercub.org/forum/showth...238#post712238

  4. #4

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    What year airplane do you have? The o-470-50 can't exhale with that early dual exhaust. I went with a Leading Edge exhaust even before they had an STC. They modified their C-206 tuned exhaust, got it field approved. Can't get a cylinder temp above 320. I looked at acorn but it looked like they just make a replacement system. Are they "opened Up"?

  5. #5

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    I'll check with Acorn.
    I've a '73 180J with single exhaust on the copilot side, factory seaplane kit.
    First I've heard of the single vs. double exhaust issue.

    Didn't Leading Edge's Dane Wagner pass away? His business is up for sale, as well:https://www.wemakeyoufly.com/news/ta...t-systems-llc/
    Last edited by JohnnyR; 03-13-2018 at 11:01 AM.

  6. #6
    hotrod180's Avatar
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    Quote Originally Posted by bubb2 View Post
    What year airplane do you have? The o-470-50 can't exhale with that early dual exhaust. .....
    Curious if that's Steve Knopp's opinion, or yours?
    Cessna Skywagon-- accept no substitute!

  7. #7
    www.SkupTech.com mike mcs repair's Avatar
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    Quote Originally Posted by hotrod180 View Post
    Curious if that's Steve Knopp's opinion, or yours?

    thats what we had to change 24 years ago also....

  8. #8

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    I called Paul @ Acorn a couple of days ago to clear up my own confusion about his mufflers. After looking up my record he told me I have flame cones. The newest STC revision muffler is available without cones. He says there's no difference in performance and that cones do help with cabin heat in very cold temperatures, but most of us don't fly in those temps. The removal of the cones simply removes any potential for cone failure and subsequent outlet obstruction.

  9. #9
    hotrod180's Avatar
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    If you don't have it, it can't break. Good operating philosophy.
    Cessna Skywagon-- accept no substitute!

  10. #10

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    Quote Originally Posted by stewartb View Post
    I called Paul @ Acorn a couple of days ago to clear up my own confusion about his mufflers. After looking up my record he told me I have flame cones. The newest STC revision muffler is available without cones. He says there's no difference in performance and that cones do help with cabin heat in very cold temperatures, but most of us don't fly in those temps. The removal of the cones simply removes any potential for cone failure and subsequent outlet obstruction.
    Paul reported to me last month that most of their mufflers currently shipping do not have flame cones.
    I believe Knisley is the same. Just a divider inside to channel the gases to outflow.
    J

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