New 170A owner with muffler question

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wingnut1231
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New 170A owner with muffler question

Post by wingnut1231 »

Good morning, I don't post on forums much so I'm not even sure this is the right place for this. I recently purchased a 170A with an O-300D, it currently has pancake mufflers installed but came with a set of the Hanlon-Wilson exhaust and I know these make better cabin heat. My question is why does the conversion use two left hand mufflers instead of the left and right? AWI lists a left and right for the 170A/B and that is the set I have. Is this a clearance issue? Thanks

Ron R.
1950
C170A
N9905A
Ron Rottmann
1950 C170A
N9905A
Former C140 Owner
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Bruce Fenstermacher
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Re: New 170A owner with muffler question

Post by Bruce Fenstermacher »

First, from my first hand knowledge ( I have pancakes and had Hanlon Wilson), Hanlon Wilson mufflers do not make more heat that the pancake mufflers. In fact, if there is a difference, the pancakes make more. You will not see a difference on your A model.

What does make a difference is the entire heat system from the front baffle to the distribution of the heat on '53 and later B models. It starts from the front baffle where a 3" duck is used with the air entering a funnel shaped end dome on the right heat shroud. Inside is a Hanlon Wilson muffler with no end plate so the air can pass over it and continue out the exit. The rest of the entire heat system is them plumbed with 3" duct and is distributed from the valve on the right side of the fire wall to the left and right side of the cabin including forward to the doors at the floor. IN the IPC the funnel on the front of the heat shroud is not shown and it happens to be the hardest part to obtain.
'53 and later. Follow the more or less straight path the heated air follows
'53 and later. Follow the more or less straight path the heated air follows
Screen Shot 2020-02-24 at 12.27.49 PM.png (65.56 KiB) Viewed 6748 times
On the retro fit '52 and earlier Hanlon Wilson system all the duct is 2". There is no funnel end dome on the right side cause the 2" duct enters the top as it exits. This is why on this system both mufflers are the same, both with end caps. The first issue is 2" duct is about half the size in the volume it can carry then 3". Second this smaller volume of air has to make a U turn in the heat shroud from where it enters and exits. Then, if plumbed properly a @" duck carries the heat from the right side to the left side of the firewall to the valve, unless you have the center heat ducting which was an option. What heat makes it to the valve above your left foot is dumped into the cabin and not distributed.
'52 and earlier retrofit. Follow the U path the heated air has to travel. Also note the end caps at the magenta arrow that seal the end of the heat shroud.
'52 and earlier retrofit. Follow the U path the heated air has to travel. Also note the end caps at the magenta arrow that seal the end of the heat shroud.
Screen Shot 2020-02-24 at 12.34.58 PM.png (50.47 KiB) Viewed 6748 times
So in short on the '52 and earlier you use the same muffler right and left which has end caps, On the '53 and later you use a different muffler with no end caps cause the air enters the front and exits the rear.
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Bruce Fenstermacher, Past President, TIC170A
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GAHorn
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Re: New 170A owner with muffler question

Post by GAHorn »

The ‘53 and later mufflers will accommodate the larger shroud the later cabin heat system utilizes while the pre-53 accommodates the ‘52/earlier system (edit: as Bruce explained.)

Also, (and the “legal” reason is)... the ASI “kit” using two left-mufflers... is actually as specified by the Cessna Service Kit which converts pancakes to HW system. (Both what we think of as “mufflers” are actually described as the identical PN 0550157-9 for both right and left on SNs 25372 and prior. In “correct” terminology they are “exhaust heaters” and you’ll note in your IPC they are the same PN. The SK uses a -1 PN to identify the complete assembly difference between R/L, but those assys use the 0550157-9 part on both sides.)

See: http://cessna170.org/forums/viewtopic.php?f=36&t=6919

PS: be sure to install the tailpipe cross-brace shown in that SK 70A51-1 (PN 0550159). It ties the left/right tailpipe clamps to the left/fwd carb-mount bolt. It’s basically 3/8” tubing flattened on the ends with a “tab” welded onto it for mounting to the carb mount.
'53 B-model N146YS SN:25713
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention.
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Bruce Fenstermacher
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Re: New 170A owner with muffler question

Post by Bruce Fenstermacher »

Rereading your post Ron, both your mufflers should be identical. If one does not have the end caps, you have the incorrect muffler for the right side. It will not work with the correct heat shroud,
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sfarringer
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Re: New 170A owner with muffler question

Post by sfarringer »

Bruce Fenstermacher wrote:First, from my first hand knowledge ( I have pancakes and had Hanlon Wilson), Hanlon Wilson mufflers do not make more heat that the pancake mufflers. In fact, if there is a difference, the pancakes make more. You will not see a difference on your A model.
Very well could be true for the A model.

But, on my '48, I was absolutely amazed at the increase in cabin heat when I gave up on my pancake mufflers and installed a new set of Hanlon Wilson type mufflers!
Ragwing S/N 18073
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wingnut1231
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Re: New 170A owner with muffler question

Post by wingnut1231 »

The ones I have are the 53' and later exhaust with the right side heat shrouds set up for the 3" ducting. After I posted the question I found more info about this on the forum which pretty much answered my question about fitment and it seems I have three options:
1) Do some cabin heat mods and fabricate an exhaust cross brace if I want to run this system
2) Buy another L/H muffler and heat shroud and fabricate cross brace
3) Keep the pancake mufflers
Ron Rottmann
1950 C170A
N9905A
Former C140 Owner
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