More exhaust questions

[a64pilot]

My exhausts are I think original 46 exhaust, straight pipes and the exhaust ends are squeezed together to flatten the pipes for some reason.
One of them, the leading edge of the flattened side has several holes drilled into it.
Two questions, first what’s the purpose for the pipes being flattened? I suspect it’s styling but don’t know.
Secondly what’s the holes for? I suspect it’s an attempt to lower the noise, but don’t see how it would, don’t really see what purpose the holes could serve.

Reason I’m asking is it’s likely that I’m sending the exhausts off for repair, and I want to keep them IAW the 1946 drawings, I believe the flattening is correct, but what about the holes?

[2066]

EBAY EXHAUST 12 14 2020.jpg (234.96 KiB) Viewed 14548 times

These are on Ebay -- item # 202981870839. I don't know the seller nor anything about the exhaust...a bit pricey, but they do look good and you'll likely find that any "repair" to yours may be a bit pricey, too. FWIW. Also, is your "triangular" exhaust bracket in good shape? If not, there's usually a repro for sale @ Wag Aero, 'though not "approved", they work and fit well. (...can't answer RE the holes, but the pinched ends are like OEM.) Mac

On edit, I see another set on Ebay -- #143659505641. While they don't look as good as the above, they're 1/3 the asking price & represented as being in good shape. Again, FWIW.

[a64pilot]

Need to chew on that, the second ones don’t look as good as what I have except for the flange on mine. I’d pass on them.
I called Acorn, price was between $600 to a max of $925 ea side, and maybe a couple of hundred bucks shipping as they are in Canada.

Do most exhausts have welded flanges like the first set on Ebay? my flanges slide and are not welded in place, it would seem that fitment may be an issue if they are welded.

Neither of my exhausts have any kind of braces, they only attach at the exhaust port. I don’t even see how braces could be fitted?

With Acorn I’d be sure of a quality exhaust that would fit, but at maybe $2,000 too.

[a64pilot]

I noticed that it appears that Wag Aero has a complete 120/140 exhaust system, but one with mufflers for roughly $1200 too.
My cowl has patched holes where someone in the past had some kind of muffler set up. maybe it came from an airplane with pancake mufflers? If so would the Wag Aero exhaust fit the same holes?

https://www.wagaero.com/cessna-120-140- ... stems.html

Wag Aero new comes in for less than Acorn repaired, but I’d suspect that for that kind of money, it’s actually new, be hard to find the original piece
Seen that many times on baffling.

[2066]

The OEMs did not have welded flanges...but, that said, most that are "repaired" do have them & fitting isn't an issue (...takes a bit of finesse to work'em up past the cylinder heads area, but easily doable.). I'd almost bet that yours would come back from Acorn with welded-in-place flanges. RE the bracket, it's a triangle support that attaches at the rear/center stud @ the oil tank with the bottom cross of the triangle from "tail pipe" to tail pipe. They often crack at the exhaust clamps, hence the reason I asked about yours...but, in any event, some cracking of the exhaust is almost inevitable without the support back there. (I'll attach a couple of pics...one with a few broken pieces & one that shows the forward attachment to the stud.) Mac

[2066]

I noticed that it appears that Wag Aero has a complete 120/140 exhaust system, but one with mufflers for roughly $1200 too.
My cowl has patched holes where someone in the past had some kind of muffler set up. maybe it came from an airplane with pancake mufflers? If so would the Wag Aero exhaust fit the same holes?

https://www.wagaero.com/cessna-120-140- ... stems.html

Wag Aero new comes in for less than Acorn repaired, but I’d suspect that for that kind of money, it’s actually new, be hard to find the original piece
Seen that many times on baffling.

I don't believe that the "150 type" tailpipes will fit through the holes where the Pancake mufflers had exited -- would require some modification. Wag's system is the 150 type. ...just an opinion, but if you were to scrap the original "straight exhaust" to go with the 150 type, and IF you can find good/cheap(er) serviceable 150 exhaust and buy the applicable STC (See the Newsletter)...well, it's an option anyhow. Either the Wag system (...or similar from Spruce or some others) will be significant expense. And, with either you'll still need to scrounge a 150 exhaust bracket (back to Ebay?)...attaches front of oil tank & out to muffs both sides. "Nothing difficult is ever easy" . Mac

[a64pilot]

The edges of the filled holes in my cowling are 10” to 10.5” from the aft edge and the centers of the holes are 12” and 12.5” from the trailing edge of the cowling.
If anyone has or had the pancake mufflers, can you measure and tell me if those dimensions are correct for the factory holes?
I have no idea if 150 mufflers will fit the same holes that the pancake ones did, if so then I should be able to fit the Wag Aero exhaust.

[a64pilot]

I have a stainless steel triangle like in your picture, but it has no clamps on the ends. I figured it had to be for an exhaust brace but didn’t know where to fit it.

The Wag Aero exh looks similar to their 150 exhaust, but a little different, and if it’s a PMA part for a 140, then it’s supposed to have an identical fit, form and function to the original?

[a64pilot]

Looking at Spruce’s offerings, it appears the difference between a 150 and a 140 exhaust system is the tail pipe has a different bend?

[2066]

I have a stainless steel triangle like in your picture, but it has no clamps on the ends. I figured it had to be for an exhaust brace but didn’t know where to fit it.

The Wag Aero exh looks similar to their 150 exhaust, but a little different, and if it’s a PMA part for a 140, then it’s supposed to have an identical fit, form and function to the original?

...from Wag's description: "Some cowl modification required." So, no, the fit isn't "guaranteed" near the original. Too, you'll still need the (150) exhaust bracket -- they're available "out there" at anywhere from +/- couple of hundred up to..I've seen on Ebay with asking price of $500. Maybe someone here has installed the Wag system and will wade in with dependable fact, but I'd sure want to confirm that "everything" comes with the system. Again, I don't believe that it does. There's some recent discussion here on the installation of the 150 type system (to include Wag Aero's) & I believe the consensus there was to expect to spend around $2,000, minimum. With today's money's worth, that probably isn't a lot(?)...but, it would still seem better economy to "repair" what you have or replace with serviceable. How 'bout your heat muffs -- in pretty good shape? That could play a role in deciding to hold on or go for new all 'round? Mac