printjunky
06-26-2013, 12:46 PM
About to strap on a new exhaust, and have been thinking for some time about what kind of mod might help manage in-cabin heat, reduce Rover Hot Foot, etc.
My first idea was to wrap the manifold, and then the downpipe to somewhere behind the driver's seat. But I pretty much have decided wrapping has too many possible negative outcomes to make me wary. Though ALL anecdotal, there are enough stories of premature rust. Though I'm a bit skeptical about that because how much water is going to remain in a wrap that is at >250 degrees? (In some cases much greater than). But still there are enough anecdotes to raise an eyebrow.
Also, even less well supported, are anecdotes about focusing more heat right at the point where the wrap ends, thus magnifying failure possibilities there, but that doesn't pass a sniff test to me. Safe to assume the entire system is capable of withstanding the highest temp the system will see. ie: right after the thicker part that attaches to the manifold; the heat would be concentrated there in a similar way, and we don't worry about that.
Keep in mind that most people are reporting positive experiences with wrap, but there are a notable number of exceptions, urging some rethinking. (Also, these people usually are not trying so much to reduce cabin temp, as underhood temps and gain HP from scavenging forces. Though the effect would be the same, basically.)
Anywhoo, so thinking of alternatives, I'm thinking a heat shield could be fabbed easily, and inexpensively. I mocked up a quick diagram of something I might try. Also learned a little about thermodynamics in the process or reading about it. Now understand a little more about how the intake manifold-mounted heat shield works ...
(It does put some heat back into the intake manifold, but it's better at RADIATING heat to the air than CONDUCTING it to the intake. The shield radiates heat from the exhaust manifold out into the air at something like 40 times the amount it radiates it back into the intake manifold)
My thoughts on the shield include some kind of (pressed?) standoff and some kind of channel to accommodate stainless wire ties. In aluminum, I'm thinking. Gauge? No idea. Galvanized flashing too flimsy?
So any thoughts, ideas, criticisms of my shadetree science, etc?
Oh, I also plan some in-cabin mods for the same ... coming soon.8379
My first idea was to wrap the manifold, and then the downpipe to somewhere behind the driver's seat. But I pretty much have decided wrapping has too many possible negative outcomes to make me wary. Though ALL anecdotal, there are enough stories of premature rust. Though I'm a bit skeptical about that because how much water is going to remain in a wrap that is at >250 degrees? (In some cases much greater than). But still there are enough anecdotes to raise an eyebrow.
Also, even less well supported, are anecdotes about focusing more heat right at the point where the wrap ends, thus magnifying failure possibilities there, but that doesn't pass a sniff test to me. Safe to assume the entire system is capable of withstanding the highest temp the system will see. ie: right after the thicker part that attaches to the manifold; the heat would be concentrated there in a similar way, and we don't worry about that.
Keep in mind that most people are reporting positive experiences with wrap, but there are a notable number of exceptions, urging some rethinking. (Also, these people usually are not trying so much to reduce cabin temp, as underhood temps and gain HP from scavenging forces. Though the effect would be the same, basically.)
Anywhoo, so thinking of alternatives, I'm thinking a heat shield could be fabbed easily, and inexpensively. I mocked up a quick diagram of something I might try. Also learned a little about thermodynamics in the process or reading about it. Now understand a little more about how the intake manifold-mounted heat shield works ...
(It does put some heat back into the intake manifold, but it's better at RADIATING heat to the air than CONDUCTING it to the intake. The shield radiates heat from the exhaust manifold out into the air at something like 40 times the amount it radiates it back into the intake manifold)
My thoughts on the shield include some kind of (pressed?) standoff and some kind of channel to accommodate stainless wire ties. In aluminum, I'm thinking. Gauge? No idea. Galvanized flashing too flimsy?
So any thoughts, ideas, criticisms of my shadetree science, etc?
Oh, I also plan some in-cabin mods for the same ... coming soon.8379