Dryer duct enclosing exhaust pipe with Coroplast on top - ideas ?

[Cd]

I'm asking for any advice on enclosing my exhaust pipe within thin aluminum dryer ducting.
I'm hoping that this would shield Coroplast panels thst would rest upon the ducting. ( Here in blue )
I plan to test it, and see how hot the ducting gets, but wanted to ask in case it has been done before.
I would guess that the only way it might work, is to make sure there is a large air gap below the exhaust pipe using large spacers ( As seen in example B using the green spacers )
Still though, I'm sure that dryer ducting would degrade quite fast under these temperatures.
I'm thinking of also creating a NACA duct on the belly pan that would feed cool air directly into the dryer duct.
Advice anyone ?

[freebeard]

If the Coroplast is in contact with the aluminum, couldn't the red and green parts be combined?

Aluminum dryer duct makes me think of flexible hose. Why not stovepipe spread open into a
C-shape?

I like the idea of the NACA duct.

[oil pan 4]

Don't use the thin stuff it's junk, use the semi flexible semi ridged stuff.

[Cd]

If the Coroplast is in contact with the aluminum, couldn't the red and green parts be combined?

Yes. That would be a good idea. It would keeo the duct from expanding outward from upward crushing force.

Aluminum dryer duct makes me think of flexible hose.

Flexible hose ? What type ?
It ( of coarse ) has to be large diameter metal.

Why not stovepipe spread open into a
C-shape?

Not sure what you mean.
I'm not sure if it was clear in the sketch, but I plan to slice the ducting, and slip it over the exhaust pipe.
It would be a huge hassle to undo the exhaust just so I could insert it inside the duct.

I like the idea of the NACA duct.

Besides cooling the temps a bit, it will also ensure I don't DIE from trapped exhaust.

[Cd]

Originally Posted by oil pan 4

Don't use the thin stuff it's junk, use the semi flexible semi ridged stuff.

I see what you mean ! I pulled it apart, and didn't know it was constructed in strips.
I'm stuck with what I have for now.
One of the perks of working at a hardware store, is that you get some good deals.
I got two four foot ducts for a dollar and change. ( image 1 )
I might go back for another tomorrow.

There is rigid pipe ducting that I was considering as well, but it would be harder to cut, more expensive, and wouldn't work well for curves.

[oil pan 4]

Originally Posted by Cd

I see what you mean ! I pulled it apart, and didn't know it was constructed in strips.
I'm stuck with what I have for now.
One of the perks of working at a hardware store, is that you get some good deals.
I got two four foot ducts for a dollar and change. ( image 1 )
I might go back for another tomorrow.

There is rigid pipe ducting that I was considering as well, but it would be harder to cut, more expensive, and wouldn't work well for curves.

Yeah use the duct sheet metal for the straight runs and the semi ridged for the bends.

[Piwoslaw]

Aluminum is great at transferring heat.
Remind me once more why no one has mentioned filling the gap with insulation?
That would reduce the temperature more than just an air gap.

Originally Posted by Cd

I'm asking for any advice on enclosing my exhaust pipe within thin aluminum dryer ducting.
I'm hoping that this would shield Coroplast panels thst would rest upon the ducting. ( Here in blue )

[Cd]

This is what I have so far.
It's steel HVAC ducting, and it is screwed to the frame of the car using 1" sheet metal screws.
I'm going to skip sandwiching the Coroplast over the ducting and just leave as it is.
The underside of the car has a coating of thick grease.( the undercoating )
It appears to be factory, and not just due to years of driving the car with a leaking engine - or so I hope.
It is really thick - 1/8" in some areas, and I'm worried about a fire hazard.
I fully expected the metal covers to rattle like crazy when I started the car, but to my relief, they don't !



The engine has an oil leak that I need to find and fix.
It leaks around a 1/4 teaspoon per week. ( or less ? )
This is the Coroplast belly pan mock up after a week under the car


I can just see that oil collecting and catching fire.
For now, I plan to have a low area in the belly pan directly under the engine with an exit hole.

I am asking for your advice guys.
I am no engineer, and if you see something that raises a red flag and makes you say " Well that's not good ! ", please let me know.
- Thanks !

[COcyclist]

Cd, I have a full belly pan under my diesel except for under the catalytic converter. I experimented with a sheet metal cover under that too. I didn’t see a mpg improvement but it really heated up the floor of the vehicle in summer. I removed it.

I would probably allow some airflow through the exhaust duct to keep things cool.