Pagoda SL Group
W113 Pagoda SL Group => Research & Development => Topic started by: 66andBlue on October 06, 2011, 03:01:38
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Prompted by a discussion on another board I thought to solicit your opinions and what you believe is the best material to insulate the cabin against the heat coming from the engine compartment and through the tunnel.
While researching material that could be used as a backing for the firewall pads I looked at quite a number of products and tried to find some hard facts behind some of the claims. Specifically what I was looking for were data on either thermal conductivity or thermal resistance of the material.
First a little bit of background.
In the USA here most of us are familiar with the "R-value" of insulating material in the construction or home appliance business. The R-value is a measure of thermal resistance and is the ratio of the temperature difference across an insulator and the heat flux (heat transfer per unit area): http://en.wikipedia.org/wiki/R-value_%28insulation%29
Note that the standard R-value is expressed as "per inch" thickness and often it is not clear whether the stated R-value in a spec sheet is the standard value or the actual one taking a different thickness into account.
Another consideration is the ability of a material to reflect radiant heat. For example, the heat in the tunnel arrives there mostly by radiation through the air and not by direct contact between metal surfaces. Radiant heat is predominantly infrared radiation and some materials, for example, anodized aluminum is claimed reflect about 50-60% of radiant heat but does not give off heat. That is the reason why there are aluminum heat shields between the manifolds and above the exhaust pipes. Some insulating materials incorporate a thin aluminum foil but to be effective it needs to be facing the heat source. These sheets should always be attached or glued directly to the chassis without an intermediate an intermediate layer. Dynamite, a sound barrier, is installed with the foil facing into the cabin; such an arrangement is not a good solution because the reflected heat is now trapped in the black polymer layer.
Here are some materials for which I could find specific information:
Thermozite: specific R= 1.3 (standard R= 3.7) {http://www.perfectfit.com/15269/154086/Carpet--Padding/Thermozite.html} Price: ~$1/sq.ft.
KOOLMAT: standard R=1.65 {http://www.koolmat.com/what.shtml} Price: $14/sq.ft.
EZ Cool Insulation: specific R= 1.6 {http://lobucrod.com/} Price: ~$0.68/sq.ft. - I am not so sure about the claimed R-values and the material collapses easily.
VB-3 with lead septum: specific R= 1 (standard R = 4) {http://cascadeaudio.com/car_noise_control/car_barriers.htm} Price: ~$17/sq.ft.
VB-4 barrier: specific R= 1 (standard R = 4) {http://cascadeaudio.com/car_noise_control/car_barriers.htm} Price: ~$8/sq.ft.
These values are in general agreement with the tabulated information for polymers provided in the Wikipedia article.
Please add you own favorite material or any other comments.
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Dynamat seems to be a market leader in this area; difficult to get in Europe, even through Amazon and similar places. I have been wanting to get some to evaluate it, but so far have not found a place that will sell it to me for a reasonable price. In the US it's widely available and used.
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Hi Cees,
Dynamat is certainly a market leader in the sound dampening business but the company is very careful not to claim anything about its heat insulation properties.
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Yes I know Alfred, but nonetheless in various other US car forums this is what is being talked about as the best also for heat. I don't have first hand experience so can't confirm or dispell, but this is what is being reported. Anyone else have any information on Dynamat insulation for heat?
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Found this also:
http://www.lizardskin.com/car-ceramic-insulation.html
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;D Hey folks, It seems that the Dynamat people claim the following: The "DYNAMAT TREATMENT" consists of Dynamat for noise, and Dynaliner for heat. Even the famous hot rodder, Chip Foose, lends his name to their advertisement.
Cheers, Hank
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Hi Hank,
you must be a true believer in "truth in advertising". ;)
If Dynamat really was that good I'd bet they would provide the numbers.
Cees,
that heat blocking paint is intruiging indeed, but I wish they would provide some proof.
I am attaching info on another product, "zero clearance". Although it doesn't mention any R-values or such it at least has some information on temperature difference with and w/o the material.
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I spent $200 on Dynamat and couldn't be more happy.... easy to apply... it has been 2 years and now on better than ever, no heat and sound is reduced, I would buy again.
Bob :)
P.S. bought mine from ebay but if I had to do again I would get from a local place ...it is really heavy and shipping was ALOT
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Heat Shield Products specializes in all kinds of heat insulation. A lot of their products go into race cars which generate a tremendous amount of heat. In a few products, such as their Thermoflect shield, they use ceramic technology, similar to that used in the Space Shuttle, that can deal with intermittent temperatures up to 2000 degrees and can reflect 90% of radiant heat. My daughter's father-in-law, who used to be a senior manager at the Kennedy Space Center, brought them to my attention. Evidently, they licensed some of their technology from NASA. Much more powerful than Dynamat for heat.
http://www.heatshieldproducts.com/category/automotive/5 (http://www.heatshieldproducts.com/category/automotive/5)
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Hi Hank,
you must be a true believer in "truth in advertising". ;)
If Dynamat really was that good I'd bet they would provide the numbers. [partial/quote]
"True believer" ....... I wouldn't blanket myself quite that dramatically;) But, Chip Foose being a multi million dollar industry, I'm guessing he would be quite careful about what he endorses. It would certainly be worth doing further research into this product if indeed, one didn't know what was available or effective in the sound deadening and heat reduction industry.
Cheers, Hank
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Hi Alfred,
While full realizing that these materials are probably NOT available to any of us. . . . .
This is what we used on the upper surfaces of the Space Shuttle for Thermal Protection. For 19 years I operated and maintained the NASA Arc-Jet facility in which development, testing and flight certification these blankets was done.
Larry in CA
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Hi Larry,
... and if it were available I bet it that a sq.ft. would cost as much as my car! :)
I wish I could find out where to purchase these polyimide foams that are used inside aircrafts:
http://www.evonikfoams.com/
The claim is that they were used in the space program but have you ever come across them at NASA?
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Alfred,
Their site has a contact point that might give you a lead to the distributer in US
http://www.evonikfoams.com/index.php?option=com_contact&view=contact&id=1&Itemid=99
My guys at work believe it is sheet form and has various thicknesses and colours. Their comment was
"It is a PVC with excellent electrical properties like Breakdown Voltage, insulation resistance, etc and shrinkage characteristic can be used in Low Tension Control Panel / Switch Gear System."
Garry
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Hi Garry,
I had contacted them some time ago (when Dynamat stopped selling their Tac-Mat which was a polyimide) and did not get far - "sorry, no retail sales".
But I'll try again.
Tell your guys to take a remedial in chemistry again. ;)
A polyimide (http://en.wikipedia.org/wiki/Polyimide) is nothing like PVC (=polyvinylchloride).
I found more info on the NASA web site and plan to dig deeper here because I like the published heat and sound dampening values of the material and it is light weight.
http://www.sti.nasa.gov/tto/spinoff1998/t3.htm
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I used the dynamat foil backed product available from Summit Racing. Excellent results, cabin is cool and quiet. Lined both footwells, extending up into the firewall, trans tunnel, driveshaft tunnel, under each seat. On the passenger side added (on top of the Dynamat) regular double foil backed bubble insulation (available from home improvement stores) This will be covered by the carpeting and not visible anyway, but makes a huge difference in transfered heat from the exhaust pipes running right under the passenger seat. Also could not be happier with the out come. Good luck!!
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The state of the art is Inconel heat shield used by Formula 1 teams
The FORD GT supercar has it in the engine bay
I'm sure some vendor can provide if you provide stencil
Its for extreme heat applications & deflects 90%