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Gold Foil...does it Work? Air Box Thermal Protection

13K views 41 replies 15 participants last post by  VenomousSVT 
#1 ·
Many of you know that the entire Rocket Science team has been hard at work developing a Thermal Protection Film Kit for the ST Air Box Cover. I freely admit to being smitten by the appearance. But...does it work. The principal is that metallic surfaces reflect long wave EM radiation and reduce heat transfer. In this case to our intake air.

It should be noted that the material used is a metallized polymer film. It is neither gold, nor is it a foil. But, I will stick with the common vernacular, and we'll call it Foil.

I performed a little experiment that shows how this works. I placed an infrared heat lamp over a stock Air Box and raised the temperature to just above 120 degrees F. One thermocouple lead was placed 1/4" above the top surface while a second was positioned 1/4" below the inside surface, with both being at the center of the Air Box Cover. The temperature was raised gradually over 30 minutes in each case, to allow the temperatures to reach equilibrium. Great care was taken to ensure that all the experimental parameters (temp, time, distances, positions, etc.) were the same for both samples.

The stock Air Box Cover, with an outside temperature of 120.9* F, showed an an inside temperature of 98.0* F, and a temperature differential of 22.9* F. The Air Box Cover that had the Thermal Protection Foil had an external temperature of 123.4*F, and showed an internal temperature of 82.7* F. A differential of 40.7* F.

In this particular case, the Thermal Protection Foil produced a significant 17.8* F reduction in temperature over stock.

I did a few other tests and noted that if heated more rapidly, there was an even larger differential. The Foil covered box showed differentials as high as 30.4*F when the temperature was raised to ~125* F in 6 minutes.

I hope you find this information interesting and useful. JP
 
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#3 ·
Thanks Wis, for the timely assistance. Folks can just zoom for the temp readings. JP
 
#4 ·
Many of you know that the entire Rocket Science team has been hard at work developing a Thermal Protection Film Kit for the ST Air Box Cover. I freely admit to being smitten by the appearance. But...does it work. The principal is that metallic surfaces reflect long wave EM radiation and reduce heat transfer. In this case to our intake air. It should be noted that the material used is a metallized polymer film. It is neither gold, nor is it a foil. But, I will stick with the common vernacular, and we'll call it Foil. I performed a little experiment that shows how this works. I placed an infrared heat lamp over a stock Air Box and raised the temperature to just above 120 degrees F. One thermocouple lead was placed 1/4" above the top surface while a second was positioned 1/4" below the inside surface, with both being at the center of the Air Box Cover. The temperature was raised gradually over 30 minutes in each case, to allow the temperatures to reach equilibrium. Great care was taken to ensure that all the experimental parameters (temp, time, distances, positions, etc.) were the same for both samples. The stock Air Box Cover, with an outside temperature of 120.9* F, showed an an inside temperature of 98.0* F, and a temperature differential of 22.9* F. The Air Box Cover that had the Thermal Protection Foil had an external temperature of 123.4*F, and showed an internal temperature of 82.7* F. A differential of 40.7* F. In this particular case, the Thermal Protection Foil produced a significant 17.8* F reduction in temperature over stock. I did a few other tests and noted that if heated more rapidly, there was an even larger differential. The Foil covered box showed differentials as high as 30.4*F when the temperature was raised to ~125* F in 6 minutes. I hope you find this information interesting and useful. JP
Good to see the data. This means I can buy one soon right?
 
#8 ·
TS, gettin' close man, real close. The top two photos show a stock Air Box Cover. The lower two, with Thermal Protection Foil. JP
 
#12 ·
Yeah Snail, "live testing" will be fun. I'd like to get one of these out to you, and you can play with it. I'd like to get about a half dozen out there, and see what kind of feedback comes in about fit and installation difficulty. @Kevin gave me some good information, and I made some changes based on his advice. His skills however, are way above average. Get those three meter probes ready. JP
 
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#9 · (Edited)
Absolutely correct SD. This is just a demonstration of the effect. In combination with a Snorkel, there could be some significant gains. Plus, it's just like I like my women, inexpensive and pretty. JP

Ed., There'll be additional testing. JP
 
#13 ·
You just love to make me work, don't you. I just got some design work from the Snorkel engineer in my mailbox. Haven't even had time to look at it. JP
 
#15 ·
@RocketST - You and your trusty helpful team are doing some amazing work. I cannot wait to see the finalized product and even if my ST isnt here yet, I want to be one of the first to help support your hardwork!
 
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#16 ·
Test

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#18 · (Edited)
Mouse, stay tuned. There's a lot more on the way. JP
 
#21 ·
The foil is a great idea and will work with moving air also, as the air will still be warmed radiantly by anything it comes in contact with so the lower the temp of the wall surface the better. As far as the snorkel goes, is there a point where the snorkel will no longer be the bottleneck in the equation when enlarged, but cause the incoming charge to lose inertia and become more turbulent.
 
#22 ·
Trouble, I agree. And there will be more test data. The snorkel's benefits are largely derived from the fact that it brings colder air to the Air Box. The Thermal Protection then reduces heat transfer keeping the air cooler. And your second point is well taken, because the velocity of the incoming air does modestly effect the static air pressure in the Air Box. So reducing that velocity would reduce air pressure. Increasing the intake size, if properly designed; while leaving the rest of the snorkel the same size and shape, will increase the air's velocity. And you are correct that turbulence generally reduces the flow velocity. JP
 
#29 ·
I'm in a trance over that "foil". So far liking the results you're getting, would like to see similar results while in motion though. Really appreciate this effort you're putting in to deliver quality products!
 
#31 ·
After attending a WEC race this weekend and taking note of the thermal foil used on the intake systems, I was pondering this exact topic to myself. I'm will most likely be wrapping my cp-e intake tube, and cold side charge pipe.
 
#38 ·
Four sessions this weekend at the track. Ambient temps went from the low to high nineties. I didn't hit this with the heat gun but the air box was barely above ambient. Other STs on the track had the air box to hot to hold your hand to for an extended period. Sorry for not getting actual temps but things busy checking brake and tire temps between 6 cars (4ST 1 GT4 1 cayman), Pipenuts blew a charge pipe x 2, I had a left rear brake issue, and DesertST, ThunderLope, and Pipenuts had ground school, not to mention all the other stuff that needs to happen at the track.
 
#39 ·
That's great news man, thanks for checking on that. I really like that track, and you were layin' down some sweet lines. I know how frenetic track days can be, and it's easy to say screw it and blow off the details. So I appreciate the input. Best, JP
 
#40 ·
is there any benefit if one was to do the inside of the airbox rather than the outside? Just surious from an asthetic perspective. If you did the inside to keep the looks of the engine bay less "shiny" would the result still be a cooler charge?
 
#41 ·
I would think it would work, but maybe not quite as well. Located on the outside, the entire box would be reflecting the heat, but having it on the inside only would allow the black box to absorb and store heat, but it might only be marginal.
 
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