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Dynamat?

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Hi Skip,
There are all kinds of insulating materials available. Dynamat is not the cheapest. Folks have used many of them with apparently good results.

I have personally used quite a bit of "Dynamat Xtreme" (the heavy type) for heat blocking & rust protection. When it is tightly rolled down over clean painted metal it absolutely excludes water from the surfaces. Sort of like metal faced undercoating. It has a thick layer of extremely sticky Butyl rubber. In fact so sticky that I find it best to put it in the freezer for a while before cutting & fitting. Certainly makes the "peel" part of "peel & stick" easier. I believe that two layers rolled down, is as effective for heat blocking as 1/4" asbestos board which I have also used in a couple of places. Have even used two layers on both sides of the panels in some of the hotter footwell locations. The aluminum facing can be painted to match the body & doesn't even show very much. You can get Dynamat in the 36 sq. ft. bulk pack.

For heat reduction I have additionally used ceramic blanket around the header down pipes & another type of blanket on the inside of the upper firewall.

The down side of this is that I now have to use the heater in winter, & can't hear car noises as easily. Up side is being much more comfortable when driving 10 hour days in 100 plus temperatures.
D
 
Used it on my 100-6 and am extremely happy with it. Before you buy it, and I agree that the 36 sq ft extreme package is the best deal, check prices on E-Bay. It is expensive, and I saved about 1/3 off the retail price by going on E-Bay. Good luck!
 
I was about to buy a Dynamat Extreme type product and the guy I was talking to told me that the stuff was directional. I was planning on installing it under the carpet and he said since I was not pointed the shiny side towards the heat, it wouldn't work. I know that some around here have used it on the cockpit interior only as we have talked about it ad nausem in the past, but is he right? I am especially worried about the drivers floor as the Longbridge 100-Six doesn't have a factory heat shield there, and I was counting on the Dynamat to give me help there.

Thanks
Patton
 
I've wondered about this also. Radiant heat is reflected by the shiny surface of aluminum. As I understand it, this is the heat that travels through the air. Conductive heating occurs when heat travels through a solid or liquid. So, to keep heat from getting from the exhaust or engine to the floorboards or firewall, aluminized material, reflective material facing towards the heat source helps prevent that transfer. Insulating material, like asbestos or closed cell foam, traps air within its structure, and air is a poor conductor of heat, so that's what keeps the heat from migrating from one side of the insulation to the other. The insulating value of materials is expressed in mathematical terms, like R-value. So where is all this going? I think that the shiny aluminum on Dynamat does little inside the cockpit. The butyl rubber is great, however, at sound attenuation. What I don't know is what is the insulating value of Dynamat.

Several folks have placed aluminum faced silica, self adhesive material on the underside of the tranny tunnel, with the aluminum facing the transmission. This material has great reflective value, but little insulating value. In my restoration, I've placed this material beneath the insulating panels on the firewall and under the driver's floorboard. This should help with radiant heat that makes it through the panels.

Inside the cockpit, a buty rubber material makes great sense for sound deadening, but for insualtion, a closed cell foam material seems more logical.

I'm no expert on any of this stuff, so when you guys poke holes in my logic, please be kind. And I'll be quite happy to learn from others' greater knowledge and experience.
 
I recently spent many long hours meticulously cutting and fitting a thermal shield product very much like (actually identical) Dynamat to the tranny side of my transmission tunnel. The theory being that the aluminum facing would radiate the heat "away" from the car. I finished this little project last week and put the refreshed tunnel in my Volvo trunk where it sat for several days in the sun.

Yesterday, I delivered the tunnel to my mechanic shop only to find that it had shed at least a dozen small pieces. They just dropped off! Under heat, the extremely sticky Butyl rubber did not adhere to the smooth inner tunnel. Some did, but not enough. I wasted both the money and a difficult weekend on this project. Before you tell me that I didn't prep the fibreglass properly - well, I scrubbed it clean with simple green and then rubbed it spotless with acetone. The Butyl rubber simply does not like smooth fibreglass surfaces. At least that is my observation.
So, as a word of caution, if you are thinking about installing Dynamat or another similar product be very sure it is compatible with the surface you're covering. I know it will work on the inside floors and firewall as a sound deadener. But as a heat barrier I am really doubtful as the aluminum is facing the wrong direction to be a radiating factor.
Randy '66 BJ8
 
Cutlass, you are basically correct.

I did a little experiment.

An aluminum plate was painted black on one side (back).
Two layers of Dynamat Xtreme were placed on the other side (front).
The outside layer of Dynamat was painted black. Under layer was unpainted.

Hot air was applied to the aluminum plate & ambient slow moving air applied to the black painted Dynamat outer layer.
Temperatures measured with an IR thermometer were measured at 168F. hot side & 143 F. cool side. A difference of 25 degrees.

The temperatures were reversed with 168 degrees applied to the painted Dynamat side. The temperature on the cool side was 123 F. A difference of 45 degrees.

Conclusion: Dynamat is nearly twice as effective when placed on the outside. However, it is by no means ineffective when placed on the inside. No doubt due to the thick layers of Butyl rubber. A 25 degree drop is still very worthwhile.

Comments:
Infrared heat does not react the same as visible light. Heat blocking is composed of reflectance of IR AND reducing conductance. When placed on the inside surface, Dynamat loses much of it's reflective properties but still has a good measure of reduced heat conductivity. An example of reduced conductance is the common hot pad used to pick up hot pots.

The aluminum plate & the outside layer of Dynamat were painted flat black to simulate the fact that the surfaces would likely be painted some color for cosmetic reasons.

If installed on the hot side & left unpainted, Dynamat would likely be more effective than these tests show. Although once the hot side is heated to a given temperature there would be no difference.

A material's reflectance of heat will occur regardless of where it is located in a sandwich of materials. ie. the under layers of aluminum still reflect infrared even when coated by some other compound. Maybe not as effectively as if the shiney side were oriented directly toward the heat source.

The above information is subject to many interpretations & could be argued endlessly. Just one take on the subject.
D
 
I'm not convinced that the aluminum on the inside of the cockpit will do anything. If the heat is conducted through the butyl rubber, and the aluminum is bound to the rubber, it will conduct the heat. Just pick up a baked potato fresh from a hot oven, tightly wrapped in aluminum foil. The aluminum conducts the heat from the potato very efficiently. Then do the same thing with an oven mitt. The butyl rubber will have insulating properties, but not too much, compared with a product actually designed to insulate from heat. Butyl rubber is dense. Effecitve heat insulation is not dense, fiberglas batting for instance. The rubber does have desireable properties, so I'm not knocking it by any means. Just don't depend upon a couple of layers of Dynamat to make the interior cool. Look at the technical specifications for the product you're interested in. I don't think Dynamat is promoted as a thermal insulator as much as a sound insulator.
 
As I said,
"The above information is subject to many interpretations & could be argued endlessly. Just one take on the subject."

The fact remains, the interior surfaces of my car remain cool after 8 hours of driving in 100 degree plus temperatures. The only things that get hot are the accelerator pedal, shift lever, & ashtray. This certainly was not the case before adding Dynamat. I like it. Maybe just too dumb to know the difference.

Truth be known, there are many insulations that will work. Us what you like. Have you actually tried anything?
D
 
Well ole pardner, I have to go along with Cutlass. You know what we do when we want to Capture heat and retain the heat in a space module ?. Paint it Black.

However, Cutlass do not overlook the fact that thermal conductivity parallels electrical conductivity. This is to say if it will not conduct electricity very well it also will not conduct Heat very well.----Keoke
 
[ QUOTE ]
I'm not convinced that the aluminum on the inside of the cockpit will do anything.

[/ QUOTE ]

Cutlass--

Why not install it on the outside of the cockpit as I did? I have it under the driver's floor directly above the exhaust pipe, inside the transmission tunnel and on the engine side of the footwell and the "extension panel". After several years service neither the aluminum nor the rubber mastic has deteriorated from the moist, oily environment found under the car nor have I experienced any separation problems from the FG tunnel as did Randy.

I have not conducted scientific tests with pie plates as did Dave Russell but it is my opinion based on impiric observation that Dynamat is extremely effective in reducing the temps in my 100's cockpit.
 
Well thanks a lot to all of you, now I am thoroughly confused under the floor on top of the floor silver in silver out. I have a headache and can hear the Jack Daniels bottle calling me now. LOL Skip
 
Hi Skip,
What it means is that ther are a number of different materials that will work & several ways to apply them. Just use whatever you think will be ok.

I can remove my posts if it will simplify things. It's one of those topics that I should probably not have gotten involved with in the first place. Kind of like discussing which is the best tire.
D
 
Just to set the record straight, I don't doubt that Dynamat Extreme will help insulate the cockpit. But if the aluminum is facing the inside, then I believe that most of the insulation value is in the butyl rubber, not in the aluminum. Applied to the outside of the car, however, the aluminum should provide a radiant heat barrier. You might want to explore the technical specs at www.dynamat.com. Some of their products do list thermal properties, and some, including Dynamat Extreme, do not. Heat insulation aside, this product is apparently very good at reducing road noise, and makes the cockpit much quieter, with a tighter feel. On my MGB, I used open cell foam, with aluminum on both sides, on the floor, with good effect.
 
Hi Skip. Not wishing to be a Firebrand here but; there is no reason for you to be /ubbthreads/images/graemlins/confused.gif . Selecting Dynamat or some other product is simply dependant upon which benefit you are most concerned with : Thermal loss or noise reduction. It is of interest to briefly note here that you actually cannot have noise reduction in panels using materials like Dynamat with out introducing a corresponding thermal energy transform. Some of the other products have defined values for both characteristics. OTOH, I can assure you that Dynamat will also produce an unqualified heat loss. Further, if it is installed as Michael pointed out you can optimise it's characteristics. The aluminum outer layer will act as a thermal radiator, its backing will provide noise suppression and thermal loss. The thermal loss is due to the backing materials low thermal conductivity or put another way it's high thermal resistance. Conceivably, if two superimposed layers of the material are used the noise reduction and thermal loss will be enhanced.---Fwiw---Keoke
 
Hi, everybody - I've read all of this with great interest, learning how what I've already done this last spring will, or will not, work. All I can tell you is that I installed Dynamat with the aluminum side "up" on the floor and tunnel, and undernealth the tunnel shiny side down. End result - a great reduction of heat and none of the pieces under the tunnel have released. That's all I know
 
Thats ok you didn't violate the rules: Shinny side down underneath.---Keoke- /ubbthreads/images/graemlins/grin.gif
 
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