Muffler Shroud - Carb Heat <> Cabin Heat Separation

Hello folks, potentially naïve question, is the muffler shroud on a PA-18 segregated into two compartments or could back fires potentially blow into the cockpit if the carb heat were on and cabin heat use partially impact carb heat effectiveness?

The heat shroud has a center baffle, ring welded around the outside of the muffler. A muffler backfire will not effect the carb heat or cabin heat unless you blow a hole in the muffler.

...which is why there is a clamp band over it.. Thanks Steve. Should have found a photo of a muffler first.

One more question on the cabin heat box if I may. Is it a mixer or just a flap. Wondering what the hole open to the (not always fresh) undercowl air is for?



Or with a Penn Yan

Flow said:

...which is why there is a clamp band over it.. Thanks Steve. Should have found a photo of a muffler first.

One more question on the cabin heat box if I may. Is it a mixer or just a flap. Wondering what the hole open to the (not always fresh) undercowl air is for?

View attachment 61516

Or with a Penn Yan

View attachment 61517

Click to expand...

The whole point of that shroud around the muffler is to capture heat, so it can be used for cabin heat or for carb heat when needed. But, when those tasks aren’t needed, that shroud is still gathering heat. When you close the cabin heat control and the carb heat control, that heat is exhausted out that opening, helped along by some intake air which pressurizes the air going through the shroud. That prevents dangerous heat buildup of the muffler.

MTV

Everyday is a school day, thanks guys.