From: "Andrew Martin andrew@martinag.com.au" <flyrotary@lancaironline.net>
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Date: Sun, 29 Oct 2023 22:31:36 +0800
Message-ID: <CAJxaVD3bjfSCRhhnbcS8kogxvkDm=vEn+B289pc8dPEyZ5HanQ@mail.gmail.com>
Subject: Re: [FlyRotary] Updates on Muffler Experiences?
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
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Hi Doug,
My setup is for a Renesis so bit different to an 86 13b, what I found
worked well is a short & compact muffler, all homemade, a 60mm perforated
ss tube welded to the mazda renesis exhaust manifold that was shortened as
much as possible. I perforated the 60mm tube with 10mm drilled holes,
enough so area of drilled holes is same as pipe inlet.  A 100mm ss tube
covers the 60mm tube and outlet of 100mm is at same end as inlet of 60mm,
this is important to send sound waves back to source (works similar theory
to ANR headset apparently). muffler is short, approx 150mm to keep it rigid
& fit the space next to the psru. end plates of muffler were cut from 6mm
plate & fully welded to both inner & outer tubes and covered with
lightweight tin can as heatshield.

If I was using p port exhaust I would mount individual mufflers directly to
each port, inner pipe same size same as port, would look like 2 cans
protruding from side of engine, connect short tailpipes (same volume as
inner perforated pipe) as close to engine end of outer pipe as possible to
exit cowl. Idea is to send sound waves straight back to where they come
from without restricting gas flow.
Probably as clear as mud, but my 2 cents worth, works a treat.
Cheers
Andrew Martin

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<div dir=3D"ltr"><div dir=3D"ltr">Hi Doug,=C2=A0</div><div dir=3D"ltr">My s=
etup is for a Renesis so bit different=C2=A0to an 86 13b, what I found work=
ed well is a short &amp; compact muffler, all homemade, a 60mm perforated s=
s tube welded to the mazda renesis exhaust manifold that was shortened as m=
uch as possible. I perforated=C2=A0the 60mm tube with 10mm drilled holes, e=
nough so area of drilled holes is same=C2=A0as pipe inlet.=C2=A0 A 100mm ss=
 tube covers the 60mm tube and outlet of 100mm is at same end as inlet of 6=
0mm, this is important to=C2=A0send sound waves back to source (works simil=
ar theory to ANR headset apparently). muffler is short, approx=C2=A0150mm t=
o keep it rigid &amp; fit the space next to the psru. end plates of muffler=
 were cut from 6mm plate &amp; fully welded to both inner &amp; outer tubes=
 and covered with lightweight tin can as heatshield.</div><div dir=3D"ltr">=
<br></div><div dir=3D"ltr">If I was using p port exhaust I would mount indi=
vidual mufflers directly to each port, inner pipe same size same as port, w=
ould look like 2 cans protruding from side of engine, connect short tailpip=
es (same volume as inner perforated pipe) as close to engine end of outer p=
ipe as possible to exit cowl. Idea is to send sound waves straight back to =
where they come from without restricting gas flow.</div><div dir=3D"ltr">Pr=
obably as clear as mud, but my 2 cents worth, works a treat.<br clear=3D"al=
l"><div><div dir=3D"ltr" class=3D"gmail_signature"><div dir=3D"ltr"><div di=
r=3D"ltr"><div>Cheers</div><div>Andrew Martin</div></div></div></div></div>=
</div></div>

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