Aluminum ceramic coated exhaust
11-21-2003, 04:19 PM
#16
Three Wheelin'
Let me whip out my Heat and Mass xfer book and look for conductivity values for AL. At 212F the K value of aluminim is 133 Btu/hr*ft*F and for Cast Iron(older Headers) its 26.8. But the higher the conductivity the more heat it'll pass to the surroundings...which would raise underhood temps! Any Chemical engineers wanna add to this...And besides arent the new manifolds AL anyway???
It does look nice though!
It does look nice though!
11-21-2003, 04:41 PM
#17
Three Wheelin'
Actually, the biggie here isn't the aluminum for heat protection but the ceramic which is what protects it. The tiles on the space shuttle are also a form of ceramic as well. Ceramic is well known to provide great heat insulation and they've even tested engine blocks made of the stuff.
As for longevity, Jet Hot was offerings lifetime warranties and said that their stuff will NOT lose the color to the finish (might get dirty though...). They also say on sound objects that are coated that they offered a replacement guarantee if that object rusted through when coated externally and internally.
As for longevity, Jet Hot was offerings lifetime warranties and said that their stuff will NOT lose the color to the finish (might get dirty though...). They also say on sound objects that are coated that they offered a replacement guarantee if that object rusted through when coated externally and internally.
11-21-2003, 05:45 PM
#18
Burning Brakes
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I guess that the idea is to form alumina (protective, insulating) on the surface by oxidizing the aluminum. My question is how does such a thin layer of alumina (microns) act as a thermal insulator? The ceramic tiles on the space shuttles rely on the huge porosity of the ceramic foam blocks that are inches thick for thermal insulation. I still think the headers look nice!
11-21-2003, 05:50 PM
#19
Well, I can tell you it does work at least a little on our FSAE car. I'll find out if they did any quantitative tests last year on the system. If not, maybe I can do some this year.
11-21-2003, 10:16 PM
#21
Nordschleife Master
just out of curiousity:
Why didn't Porsche do this stock from the factory? Is it possible that keeping so much heat in the exhaust passing through the wastegate and crossover will raise the temperature of the turbine? Some of the heat radiating away might be a feature that saves wear and tear on the wastegate and turbine.
Dunno, just a thought. I know the spinning/friction of the turbine causes it to get pretty hot anyways..
Why didn't Porsche do this stock from the factory? Is it possible that keeping so much heat in the exhaust passing through the wastegate and crossover will raise the temperature of the turbine? Some of the heat radiating away might be a feature that saves wear and tear on the wastegate and turbine.
Dunno, just a thought. I know the spinning/friction of the turbine causes it to get pretty hot anyways..
