More exhaust questions

[a64pilot]

Has anyone had any luck getting their cabin and carb heat shrouds repaired? Mine fit horribly and with the cold weather moving in I'd love to find a way to help them seal a little better. I saw on the second set posted on Ebay there was a new style shroud. Any idea what that might be?

I believe that was a home brew muffler type of shroud. I doubt due to its length that it would provide much heat. Works on mufflers likely due to their large diameter, its surface area to transfer heat that your after, so if a small pipe, then a long shroud, fat muffler a shorter one will work.
I memory serves the cockpit heat shroud has a fresh air intake and therefore you could seal both ends of the shroud with fiberglass wrap and or maybe header wrap to help prevent air leaks, over the pipe and under the shroud of course.
However the carb heat muff again if memory serves pulls it’s air from around the upper hole where it wraps around the header, so do not try to seal that area as of course then your blocking airflow and carb heat becomes a choke.

If you find a way to increase the surface area of the pipe under the muff, that should increase heat output, but wouldn’t be easy I don’t think.

I don’t know if you have ever worked on a VW air cooled motor, but they were heavily finned under the shroud to transfer heat.

[a64pilot]

As an update, I got the pipes in and installed, at least partially, still waiting on the nuts to install the brace.
However on my pipes/ shrouds, the fit is actually slightly an interference fit, meaning there is zero, zip, nada clearance between the two, which of course makes sense as the muff is clamped to the pipe, so there is no way any header tape is going in there, maybe a wrap of fiberglass cloth, but certainly not header tape.
So I put mine back the way they came off, that is clamped directly to the pipe, and I believe as long as the clamp stays tight, there will be no movement, and therefore little or no wear.

As an aside note, as the heater muff covers about three ft of pipe and can of course draw on the whole length of pipe to get heat, my heater performs at least as well as say a C-210’s or 182’s does.

Now the heat in my Maule had to be experienced to be believed, as it was a fuel injected engine and a 540, both mufflers were used for cabin heat, one for the front seat and the other for the back seat, but that’s a whole other story.

I’d be willing to bet that the 46 straight pipe exhaust provides as much if not more heat than a muffler as it covers a whole lot more pipe.

[6277]

I have the straight pipe system. The heat is not very good.

[a64pilot]

I have the straight pipe system. The heat is not very good.

Then you must have air leaks or something, because I can assure you that pipe is hot.
But then it’s also I guess a matter of OAT, I don t fly in real cold weather,because. won’t live in real cold weather.

[2066]

I have the straight pipe system. The heat is not very good.

Ray, do you have the "scoop" up front for ram air into your cabin heat muff? Also, you might look closely at the firewall heat control valve & diffuser (inside firewall) to be sure they're functioning OK. My heat is very good, too...but have to admit it's more comfy for the passenger than for me as it really heats my right foot better & before than the rest of me. Mac

[6277]

I do have the scoop. If it's around 30F I can manage. I do have some cracks around the doors that allow fresh (cold) air in. I have been out in 20-25 degree weather. My feet are warm, but I can see my breath and if I have a passenger, the windscreen fogs up on the ground and I have to open the door a crack to clear it. My preheater is an 1875 watt hair dryer with the flow directed on the oil tank with a comforter around the cowling tucked in around the prop to keep the warm air in. I do have the block off plates in the cowling. It only takes about 30 minutes and the cylinders are warm to the touch and oil is around 100.

[2066]

I do have the scoop. If it's around 30F I can manage. I do have some cracks around the doors that allow fresh (cold) air in. I have been out in 20-25 degree weather. My feet are warm, but I can see my breath and if I have a passenger, the windscreen fogs up on the ground and I have to open the door a crack to clear it. My preheater is an 1875 watt hair dryer with the flow directed on the oil tank with a comforter around the cowling tucked in around the prop to keep the warm air in. I do have the block off plates in the cowling. It only takes about 30 minutes and the cylinders are warm to the touch and oil is around 100.

It may be that it's as good as it gets. Attention to sealing every little seam and both ends of the muffs might make a bit of difference, but our planes are notorious for having plenty of "circulation" in/out of cabin. Donna reminds me of a couple of convention trips to MN and your state and just how chilly our upper bodies were (and, the cold air on her neck) on cooler days "up there". Some have carefully installed new door seal and even added upper/rear latches to hold that area tight(er) in flight...but I question how much that even helps (John C. has observed in the past that some doors may be cracked, allowing/exacerbating that rear/upper "air hole", so worth checking). ...good news is that any exhaust leaks in the cabin are pretty much blown through...immediately? . Mac

[a64pilot]

Just as an update, I have the Wag Aero bracket installed.
You will have to bend it to clear the right side engine mount, but it’s an easy bend.

8DA36AA3-2775-40EA-B35D-4B0A6B170684.jpeg (47.18 KiB) Viewed 13140 times

If you look you can see how the bend gives clearance, there is maybe one thread showing on the stud, no washer was used.

DE65759E-1EF2-4C4D-ABDB-4FF26A1BEC9B.jpeg (78.33 KiB) Viewed 13140 times

Mine doesn’t fit really well, and I’d assume there is enough difference between sets of pies so that it never will.
If I still had my welder, even a buzz box it would have been easy to cut and reweld for a perfect fit.

[2066]

"...cut and reweld for a perfect fit".

Yep, I've had to do that a few times over the years (...changed pipes a few times in 36 years owning -- they're never the same distance apart). Anything you can do to have a firm fit, but without being "sprung" will help prevent cracking. your installation looks good!! RE the stud, I have had that one break, right at the drilled hole, and I replaced it with an undrilled that's a bit longer. Mac

[6643]

If you find a way to increase the surface area of the pipe under the muff, that should increase heat output, but wouldn’t be easy I don’t think.

Just noticed this. Alons and Mooney M10s had a pair of springs (Home depot screen door springs) wrapped barber pole style around the pipe.