[Tom Droze]

I am curious to know if anyone is concerned with or has at least thought about the amount of heat that is absorbed by our airbox, which in turn heats the air going into the intake track? I was looking at radiant barriers as a means to deflect heat away from the airbox to prevent heat soak. I have probably had one too many Heinekens but I am thinking about wrapping the outside of my airbox in this material and the cool thing is it kind of looks like carbon fiber and it's functional:

http://www.amazon.com/JEGS-Performan...productDetails

[hassmaschine]

I'd start with measuring it to see if there's really a problem.

I'd like a Heineken

[Tom Droze]

Originally Posted by hassmaschine

I'd start with measuring it to see if there's really a problem.

I'd like a Heineken

Good idea!

I am going to drill a hole in the airbox and drop my meat thermometer probe down into the airbox. But first, I need to pop open another Heineken!

[Route 16]

thought about it too but i was thinking of putting DEI gold wrap inside the box

[Tom Droze]

Originally Posted by Route 16

thought about it too but i was thinking of putting DEI gold wrap inside the box

I contemplated that too but the reflective barrier needs to be directed toward the heat source, so it really needs to be on the outside of the airbox.

[Tom Droze]

http://www.heatshieldproducts.com/au...ermal-barriers

[Route 16]

Originally Posted by Tom Droze

I contemplated that too but the reflective barrier needs to be directed toward the heat source, so it really needs to be on the outside of the airbox.

how about preventing the heat being absorbed to the box?

[rhombus]

There are different kinds of heat transfer. The foil is designed to reflect radiant heat waves. Think of radiant heat as a heat transfer that does not require a medium (eg. air) to transfer the heat. Example is the sun. We feel the sun's radiant heat even when its 30degF outside. The radiant energy of the sun travels through the vacuum of space and our atmosphere. It does not heat up the space around the sun or our atmosphere but instead heats the surface of the earth and any objects on it. Think how a bonfire can feel very hot even when standing far away. This is radiated heat.

The exhaust manifolds are the prime source of radiated heat in the engine bay (the engine itself is a lesser extent). This is the only area that will really benefit from something like gold foil.

The radiator on the other hand is designed to heat the air that passed through it. This is convection heat transfer. Air that passes through the radiator picks up heat from the hot engine coolant and enters the engine bay. In the engine bay the hot air will transfer its heat energy into any objects that are cooler than the air temp through contact (convection). Heat reflective foils will not prevent this transfer because the air itself will just heat up the foil and whatever the foil is attached to. To reduce convective heat transfer, we have to use materials that have a lower heat transfer rate, eg higher insulation properties. Plastic is actually a good heat insulator. It has a much lower heat transfer coefficient than a metal like aluminum, thus making plastic a good choice for making an intake. Silicone also has a low transfer coefficient and is also a good choice.

The other thing to consider is the velocity of the air moving through the intake. If its fast enough, it wont have much time to pick up heat from the pipe it is traveling in. The largest interaction the air has is with the filter element. The air is in contact with the filter and can pick up heat as it passes though.

I personally only see a few degree temp rise between outside air temps and the temps at the MAF after it passed through airbox/filter. You can access the OEM MAF temp sensor using a bluetooth OBD dongle and an app on your phone. Sitting still, or in traffic the intake temps will climb due to heat soak. Once the car is moving again, intake temps quickly drop back to near ambient.

If you want to experiment with probes, the probes should be placed in the air stream but insulated from the airbox or pipe. You want to read the air temp not the temp of the airbox/pipe itself. Use a piece of silicone hose to insulate the temp probe from the pipe. Make sure any probes installed after the MAF are well sealed to prevent unmetered air from entering the engine.