Just throwing out some theory here, but given our cars have no form of intercooling, it seems any way to reduce the intake charge temp and keep heat where it is needed wold be welcome. Thermal coated manifolds, turbine housing, exhaust runners, and downpipe would help spool and greatly reduce radiant under-hood temps. I've been trying to find what the affects, if any, the coated turbine housing would have on transferring all that trapped heat to the uncoated CHRA and compressor...and if so, would a heat emmiting coating on them help elevate it. Couldn't find any definitive answer, but came across this post at Evolutionm.net that gave me another idea
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The goal of a coated intercooler, aside from protecting it from the elements, is the raise its emissivity.
Do some googling on emissivity and you'll see why it would be quite beneficial to an intercooler, especially in situations where airflow over the intercooler is limited, but it has plenty of space into which it could be radiating heat.
Aluminum, normally, has a very LOW emissivity (like gold/silver/chrome/etc): it radiates very little of its heat for any given temperature. If you can raise the emissivity, it will disperse much more of its heat without any airflow over it at all. That's not to say it will work a lot better in conditions with tons of airflow- in those conditions the difference may be marginal. But a FMIC with a high emissivity sitting around in traffic will radiate a lot of its heat away with very little airflow.
Almost anything black will have a high emissivity, black electrical tape has one of the highest emissivities and is often used as a calibrating material with infrared thermometers. (which only measure thermal flux, not temperature) Cast iron has a fairly high emissivity as far as metals go, thanks in part to the high carbon content. Stainless steel has a fairly low emissivity. (giving it an unusual combination of low thermal conductivity and low emissivity, the opposite of what you'd want for an intercooler, but exactly what you'd want for exhaust parts) Polished aluminum has next to zero emissivity, beaten only by polished silver and, of course, Gold.
Emissivity is the inverse of thermal reflectivity, hence why Gold is often used as a thermal reflector. You could just as easily coat the outside of your headers/cast-iron-manifold with gold and they would radiate almost no heat to the surrounding environment. (conduction and convection, on the other hand ... lol) Polishing stainless steel headers would do the same job alllllllmost as well, but not quite.
Black paints, if thin enough, won't impede the conductivity of the intercooler enough to overcome the increase in emissivity. A lot of factory intercoolers/radiators are "painted" black for that reason. (borderlines on dying them because the paint is so thin)
The trick to "Thermal Dispersant" coatings is to get high thermal conductivity AND high emissivity, which are almost always mutually exclusive. My understanding, though don't quote me on this, is that they impregnate the material with strands/flakes of a material (like gold/silver) which has a high thermal conductivity, but don't allow the strands/flakes to make up a significant portion of the surface. That way, the gold/silver conducts the heat to the surface of the coating, where the high emissivity radiates it away more efficiently than the substrate itself would be capable of doing.
Important Note:
Thermal Dispersants are also excellent thermal absorbants. That means that if the backside of your intercooler is right next to your 200*F radiator, and the backside of the intercooler is coated with a thermal dispersant, instead of dispersing more heat, it will ABSORB more heat. You'd actually better off NOT coating the backside of the intercooler if it is facing a hot object; in fact, polishing it to a shine would turn the aluminum into a VERY good thermal reflector and reflect most of the heat back away from the intercooler.
Anyway ... read about emissivity! It's interesting stuff and google will provide you will more answers than I ever could.
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What I'm getting from this is that polishing the "bottom" of the aluminum intake manifold, the Compressor, and the carb base/elbow might be beneficial in keeping out heat. Thoughts?
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The goal of a coated intercooler, aside from protecting it from the elements, is the raise its emissivity.
Do some googling on emissivity and you'll see why it would be quite beneficial to an intercooler, especially in situations where airflow over the intercooler is limited, but it has plenty of space into which it could be radiating heat.
Aluminum, normally, has a very LOW emissivity (like gold/silver/chrome/etc): it radiates very little of its heat for any given temperature. If you can raise the emissivity, it will disperse much more of its heat without any airflow over it at all. That's not to say it will work a lot better in conditions with tons of airflow- in those conditions the difference may be marginal. But a FMIC with a high emissivity sitting around in traffic will radiate a lot of its heat away with very little airflow.
Almost anything black will have a high emissivity, black electrical tape has one of the highest emissivities and is often used as a calibrating material with infrared thermometers. (which only measure thermal flux, not temperature) Cast iron has a fairly high emissivity as far as metals go, thanks in part to the high carbon content. Stainless steel has a fairly low emissivity. (giving it an unusual combination of low thermal conductivity and low emissivity, the opposite of what you'd want for an intercooler, but exactly what you'd want for exhaust parts) Polished aluminum has next to zero emissivity, beaten only by polished silver and, of course, Gold.
Emissivity is the inverse of thermal reflectivity, hence why Gold is often used as a thermal reflector. You could just as easily coat the outside of your headers/cast-iron-manifold with gold and they would radiate almost no heat to the surrounding environment. (conduction and convection, on the other hand ... lol) Polishing stainless steel headers would do the same job alllllllmost as well, but not quite.
Black paints, if thin enough, won't impede the conductivity of the intercooler enough to overcome the increase in emissivity. A lot of factory intercoolers/radiators are "painted" black for that reason. (borderlines on dying them because the paint is so thin)
The trick to "Thermal Dispersant" coatings is to get high thermal conductivity AND high emissivity, which are almost always mutually exclusive. My understanding, though don't quote me on this, is that they impregnate the material with strands/flakes of a material (like gold/silver) which has a high thermal conductivity, but don't allow the strands/flakes to make up a significant portion of the surface. That way, the gold/silver conducts the heat to the surface of the coating, where the high emissivity radiates it away more efficiently than the substrate itself would be capable of doing.
Important Note:
Thermal Dispersants are also excellent thermal absorbants. That means that if the backside of your intercooler is right next to your 200*F radiator, and the backside of the intercooler is coated with a thermal dispersant, instead of dispersing more heat, it will ABSORB more heat. You'd actually better off NOT coating the backside of the intercooler if it is facing a hot object; in fact, polishing it to a shine would turn the aluminum into a VERY good thermal reflector and reflect most of the heat back away from the intercooler.
Anyway ... read about emissivity! It's interesting stuff and google will provide you will more answers than I ever could.
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What I'm getting from this is that polishing the "bottom" of the aluminum intake manifold, the Compressor, and the carb base/elbow might be beneficial in keeping out heat. Thoughts?
