Cherokee exhaust repair?

[[email protected]]

Hey all... I'm thinking it's getting close to where the mufflers in my Cherokee 180 could stand
to be repaired/replaced. Any thoughts on a good place to have it done? This is the dual-muffler style
as is on the clamshell-cowled later -180's.

Also, I'd be interested to find out if there's any way to get a certified muffler that doesn't
have the internal baffles. The recurrent inspection is kinda a pain, and I could use a little more power
that a freer-flowing exhaust might provide. I know some planes (like my friend's PA-24-250) has a
muffler without internal baffles.... it'd be nice to do the same.

Thanks,
-Cory

--

************************************************** ***********************
* Cory Papenfuss, Ph.D., PPSEL-IA *
* Electrical Engineering *
* Virginia Polytechnic Institute and State University *
************************************************** ***********************

[Ray Andraka]

wrote:

> Hey all... I'm thinking it's getting close to where the mufflers in my Cherokee 180 could stand
> to be repaired/replaced. Any thoughts on a good place to have it done? This is the dual-muffler style
> as is on the clamshell-cowled later -180's.
>
> Also, I'd be interested to find out if there's any way to get a certified muffler that doesn't
> have the internal baffles. The recurrent inspection is kinda a pain, and I could use a little more power
> that a freer-flowing exhaust might provide. I know some planes (like my friend's PA-24-250) has a
> muffler without internal baffles.... it'd be nice to do the same.
>
> Thanks,
> -Cory
>
Aerospace welding or Dawley will rebuild your muffler to like-new
condition.

[RST Engineering]

So will Knisley out in Loomis (Sacramento). It is pretty much a function of
where you live to save on shipping charges. There are half a dozen really
good muffler shops in the country.

Jim


> Aerospace welding or Dawley will rebuild your muffler to like-new
> condition.

[Bob Noel]

In article >,
"RST Engineering" > wrote:

> So will Knisley out in Loomis (Sacramento). It is pretty much a function of
> where you live to save on shipping charges. There are half a dozen really
> good muffler shops in the country.

but do they have peanuts? don't forget the peanuts.

--
Bob Noel
(goodness, please trim replies!!!)

[JGalban via AviationKB.com]

Ray Andraka wrote:
>
> Aerospace welding or Dawley will rebuild your muffler to like-new
>condition.

I'll second that. I've had work done by both of these shops and I couldn't
tell the rebuilt products from new. Very good quality.

John Galban=====>N4BQ (PA28-180)

--
Message posted via AviationKB.com
http://www.aviationkb.com/Uwe/Forums.aspx/aviation/200708/1

[[email protected]]

wrote:
> Hey all... I'm thinking it's getting close to where the mufflers in my Cherokee 180 could stand
> to be repaired/replaced. Any thoughts on a good place to have it done? This is the dual-muffler style
> as is on the clamshell-cowled later -180's.

> Also, I'd be interested to find out if there's any way to get a certified muffler that doesn't
> have the internal baffles. The recurrent inspection is kinda a pain, and I could use a little more power
> that a freer-flowing exhaust might provide. I know some planes (like my friend's PA-24-250) has a
> muffler without internal baffles.... it'd be nice to do the same.

> Thanks,
> -Cory

You could use this as an excuse to put on Power Flow exhaust.

--
Jim Pennino

Remove .spam.sux to reply.

[[email protected]]

wrote:
: wrote:
: > Hey all... I'm thinking it's getting close to where the mufflers in my Cherokee 180 could stand
: > to be repaired/replaced. Any thoughts on a good place to have it done? This is the dual-muffler style
: > as is on the clamshell-cowled later -180's.

: > Also, I'd be interested to find out if there's any way to get a certified muffler that doesn't
: > have the internal baffles. The recurrent inspection is kinda a pain, and I could use a little more power
: > that a freer-flowing exhaust might provide. I know some planes (like my friend's PA-24-250) has a
: > muffler without internal baffles.... it'd be nice to do the same.

: > Thanks,
: > -Cory

: You could use this as an excuse to put on Power Flow exhaust.

From what I've heard (from Art Matteson, IIRC), the dual-exhaust cherokee muffler setup already has a very low
backpressure exhaust. The Powerflow helps the most on the Cherokees with the single muffler near the firewall. Besides, I'm
pretty sure that if we changed exhaust, we'd lose our autogas STC.

-Cory

--

************************************************** ***********************
* Cory Papenfuss, Ph.D., PPSEL-IA *
* Electrical Engineering *
* Virginia Polytechnic Institute and State University *
************************************************** ***********************

[150flivver]

On Aug 22, 10:03 pm, wrote:
.... Besides, I'm pretty sure that if we changed exhaust, we'd lose our
autogas STC.
>
> -Cory
> ************************************************** ***********************
> * Cory Papenfuss, Ph.D., PPSEL-IA *
> * Electrical Engineering *
> * Virginia Polytechnic Institute and State University *
> ************************************************** ***********************

I don't see how installing a Powerflow exhaust will invalidate an
autofuel STC.

[[email protected]]

150flivver > wrote:
: On Aug 22, 10:03 pm, wrote:
: ... Besides, I'm pretty sure that if we changed exhaust, we'd lose our
: autogas STC.
: >
: > -Cory
: > ************************************************** ***********************
: > * Cory Papenfuss, Ph.D., PPSEL-IA *
: > * Electrical Engineering *
: > * Virginia Polytechnic Institute and State University *
: > ************************************************** ***********************

: I don't see how installing a Powerflow exhaust will invalidate an
: autofuel STC.

The autofuel STC is very complicated for -160 and -180 hp PA-28's. Unlike for 150 hp -140's or -150's, the Petersen
PA-28 high-compression STC is more than just a sticker for the fuel filler on the tank. Basically, the ones that are even
applicable must have the dual exhausts. If they have the aluminum, flip-up cowling they are not applicable due to vapor-lock
issues with the muffler near the firewall. Even the ones applicable require replacement of the electric fuel pump with dual
(redundant) electric fuel pumps and some re-plumbing.

Bottom line is that with a different exhaust, the autofuel STC would most likely have to be re-approved, which would
amount to doing a whole 'nother autofuel STC certification.

-Cory

--

************************************************** ***********************
* Cory Papenfuss, Ph.D., PPSEL-IA *
* Electrical Engineering *
* Virginia Polytechnic Institute and State University *
************************************************** ***********************

[Jay Honeck]

> I'll second that. I've had work done by both of these shops and I couldn't
> tell the rebuilt products from new. Very good quality.

That's because it *is* new. The whole "rebuilt exhaust" thing is
absurd. They start with a two-square-inch piece of a collar off your
old exhaust system, construct the whole thing with new material, and
call it a "rebuilt".

Kinda like "rebuilding" a P-51 Mustang starting with nothing but a
data plate.
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

[150flivver]

On Aug 23, 7:51 pm, wrote:
> 150flivver > wrote:
>
> : On Aug 22, 10:03 pm, wrote:
> : ... Besides, I'm pretty sure that if we changed exhaust, we'd lose our
> : autogas STC.
> : >
> : > -Cory
> : > ************************************************** ***********************
> : > * Cory Papenfuss, Ph.D., PPSEL-IA *
> : > * Electrical Engineering *
> : > * Virginia Polytechnic Institute and State University *
> : > ************************************************** ***********************
>
> : I don't see how installing a Powerflow exhaust will invalidate an
> : autofuel STC.
>
> The autofuel STC is very complicated for -160 and -180 hp PA-28's. Unlike for 150 hp -140's or -150's, the Petersen
> PA-28 high-compression STC is more than just a sticker for the fuel filler on the tank. Basically, the ones that are even
> applicable must have the dual exhausts. If they have the aluminum, flip-up cowling they are not applicable due to vapor-lock
> issues with the muffler near the firewall. Even the ones applicable require replacement of the electric fuel pump with dual
> (redundant) electric fuel pumps and some re-plumbing.
>
> Bottom line is that with a different exhaust, the autofuel STC would most likely have to be re-approved, which would
> amount to doing a whole 'nother autofuel STC certification.
>
> -Cory
>
> --
>
> ************************************************** ***********************
> * Cory Papenfuss, Ph.D., PPSEL-IA *
> * Electrical Engineering *
> * Virginia Polytechnic Institute and State University *
> ************************************************** ***********************

The autofuel STCs I've seen are for airframe and engines with no
reference to the type of exhaust system. In general, higher
compression engines don't have an STC for autofuel because of the
increased chance of detonation. Still don't see how a different
exhaust would increase the likelihood for detonation in a low
compression engine.

[[email protected]]

: The autofuel STCs I've seen are for airframe and engines with no
: reference to the type of exhaust system. In general, higher
: compression engines don't have an STC for autofuel because of the
: increased chance of detonation. Still don't see how a different
: exhaust would increase the likelihood for detonation in a low
: compression engine.

http://www.autofuelstc.com/autofuelstc/pa/wa.html
http://www.autofuelstc.com/autofuelstc/pa/serialnumbers.html

There are a number of issues. Detonation is only one. Others include vapor lock (exacerbated by
exhaust location and configuration), hydro-lock (boiling fuel in the carb... that's why the PA-24 isn't
applicable, for instance), etc. I agree that for *almost all* autofuel stc's, (high compression or low
compression) there isn't anything to it.

For the PA28 with -160 or -180, there is a lot to it, and exhaust was an important reason why
some are applicable and some are not.

-Cory


--

************************************************** ***********************
* Cory Papenfuss, Ph.D., PPSEL-IA *
* Electrical Engineering *
* Virginia Polytechnic Institute and State University *
************************************************** ***********************

[Steve Foley]

> wrote in message
...

>
> For the PA28 with -160 or -180, there is a lot to it, and exhaust
> was an important reason why
> some are applicable and some are not.
>
> -Cory

What I found interesting is that when I overhauled my engine, I upgraded
from a 150HP to 160HP. It involved different pistons and wrist pins.
Everything else stayed the same, including fuel burn.

This upgrade invalidated my autogas STC. I called Petersen, and they said I
needed the one with the fuel pump. I think that's a little strange, as the
fuel system did not change.

[[email protected]]

Steve Foley > wrote:
: > For the PA28 with -160 or -180, there is a lot to it, and exhaust
: > was an important reason why
: > some are applicable and some are not.
: >
: > -Cory

: What I found interesting is that when I overhauled my engine, I upgraded
: from a 150HP to 160HP. It involved different pistons and wrist pins.
: Everything else stayed the same, including fuel burn.

: This upgrade invalidated my autogas STC. I called Petersen, and they said I
: needed the one with the fuel pump. I think that's a little strange, as the
: fuel system did not change.

Don't even get me going on that. It's a bull**** rule that basically stems from the fact the
Piper's PA-28 fuel system was marginal to begin with. Before we bought the STC, I talked with Petersen
directly about octane, why the STC was the way it was, etc. He said that the problem was "inadequate
fuel flow," with the stock Piper pump and it wouldn't pass what he called the "ditch test." Full-power,
with the plane in a very nose-high attitude (i.e. tail in a ditch) and the fuel pump didn't maintain
enough pressure. Also, on his test plane, the right tank flowed a little better than the left, so the
autofuel STC requires takeoff and landing on the right tank.

It was exactly my point that swapping pistons to make a -150 a -160 doesn't change the fuel flow
at all... yet by some magic, the pump is no longer adequate. It's bull****, but unfortunately that's
the way the legality of the system requires.

-Cory

--

************************************************** ***********************
* Cory Papenfuss, Ph.D., PPSEL-IA *
* Electrical Engineering *
* Virginia Polytechnic Institute and State University *
************************************************** ***********************