Would someone that is claiming that belangers run cooler than other stainless headers explain their reasoning behind their claim. Also, when doing so, make sure you are comparing ceramic coated stainless headers to the belangers. This is my thought on the subject:
By coating both, the emmissivity constants should be about equal for both types of headers, therefore at equal temperatures both headers should emit about the same amount of radiation. If you want to take into account the conduction of energy through the tube walls, then the stainless would actually allow less heat to reach the surface of the header in a transient analysis. Stainless has a lower coefficient of thermal conductivity than mild steel and a much lower thermal conductivity than aluminum. If you wanted to calculate the thermal conductivity (or conversly the thermal resistivity) of the aluminized steel, you would take into account the thermal conductivity of both materials, mild steel and aluminum, in series as you would two resistors in an electric circuit. This number (thermal conductivity) will be much higher than the stainless thermal conductivity therefore allowing more heat energy to reach the surface of the aluminized header than the stainless header. So if more energy reaches the surface of the header, then the emissivity of the material also increases, therefore transferring more heat to the engine compartment. Now, I know the ceramic coating on either material definitely reduces the amount of radiation energy emitted to the surrounding components, but since emissivity is dependent on surface temperature, the material with the highest surface temperature, aluminized steel, is going to give off more energy to the engine bay. Oh and 304 SS has about 3 times the tensile strength of mild steel at 1000 F. Someone chime in if I have made a mistake, an incorrect assumption, or if I'm just plain wrong on something. It's been awhile since I had this in school.
