How much will I need to put under a carpet in a '78 and which is better?

 

generally speaking most feel the Dyno Mat,
is a better heat and noise barrier.

However those that are watching their pennies feel the Reflectix, does nearly as good of job, at a much lower cost.
( and you can buy the Reflex at lowes/Home Depot )
a small 25x2ft. roll will cover all your front cabin, but not the rear cargo area, buy a second roll if you wish to do that area.
good Luck 69VETT

 

They are two different products for two entirely different purposes. They are used together...not one instead of the other.

Dynamat is a sound deadening material and Reflectix is a heat barrier. They have completely different properties so Dynamat won't guard against heat and Reflectix won't guard against vibrations.

The Dynamat or comparable sound deadener would go down first on the bare floors and panels of the cabin. The Reflectix goes next, followed by carpet.

 

I have my own concept regarding that topic. You just cant fight drive train and exhaust heat from the inside, you should stop it "before" getting inside the cabin, by using heat shields under the car and in transmission tunnel and firewall areas, and around the exhaust pipe. The kind of heat which you feel inside the cabin is a radiant heat, not a surface transfered.

 

another angle:

http://forums.corvetteforum.com/show....php?t=1790043

 

I put the Dynamat Extreme in all the major areas, bought a 36 sq ft package. It was not enough. But it was enough to do the firewall, tranny tunnel and sitting area. Bought a roll of Fatmat (cheaper) to do the rear, it is not nearly as adhesive as the Dynamat, have had problems with it wanting to pull loose after a day or so (after I had cleaned the areas with laquer thinner). Then I covered the major heat area's with Reflectix. Used 3M Contact spray glue and aluminum taped the seams.

I do agree with Hamad, I would like to stop it before it ever enters the car from underneath but too many other projects in front of that one for now.

 

Yes, don't forget te obvious and the source of all that heat. I'm gonna well insulate when the tranny gets swaped out, and also check the exhaust. Maybe an easier or concurrent fix with the interior, under carpet changes.

 

I agree that, ideally, you should dissapate as much exhaust and tunnel heat from below the cabin first...if that is at all possible. However, the Reflectix IS effective, even if you don't do the 'heat shield' thing first. I put Reflectix in the front half of the cabin when I lived in Phoenix and it made a world of difference. Before, I couldn't get the cabin cooled down in summer weather; after installing Reflectix, I had no problem doing so. (Here's at least ONE testimonial to its effectiveness.)

 

I used Reflectix and it works great....a noticeable difference in heat and sound. I needed 2 rolls and bought it at Menards for a fraction of the "offcial" products for the car. It is super moldable and I taped each piece together with aluminum tape. I am thouroughly satisfied.

 

What exactly is reflectix? How thick is it? Is the foil around a polystyrene core?

Dynomat does have a heat insulator fyi.

Here is my perspective: I bought a heat/sound insulator mat from a company on here. I can't remember the name off of the top of my head. I installed it in my 2000 cpe. I used the aluminum tape to adhere the product, no glue (thankfully). As far as a heat barrier it seems to be pretty effective. I live in South FL, and am running long tube headers in that car. the heat has been reduced, but I can still feel it. (someone mentioned stopping the heat before getting in the car...) The problem with the product is fit. With that mat all over the cabin... I had to remove some of the factory insulation in certain areas, and my subwoofer box doesn't fit right in the trunk. As far as sound deadening, I didn't notice any. I still wear earplugs on the highway.

My current resto product is getting lizard skin. I'm actually prepping it right now. (Yes you can make your own). I went with the pre-made product. It will be some time before I can tell you the results. I am spraying the ceramic heat barrier material under the car, in the tunnel and where the pipes will run. (I am also replacing the factory heat shielding with reproduction products). On the interior I will use the sound deadening product. I will spray both products and do the accompanying prep. It will be a while before I can give you the feedback on the product.

Note: I have not used a decibel meter to determine sound reduction.

 

Is there a problem with the reflectix getting squashed and needing replacement?

If so, can it be pulled up easily to replace?

I need to do this job but still have not decided which product to use.

 

I went the comparable route that Matt is eluding to. There are cheaper but similar products to Dynamat. I didn't do a scientific analysis, but a side-by-side comparison. They looked the same to me . . . I used one called B-Quiet. There are others. It did help reduce the heat.

 

Here's a recent post where I installed a stereo and added both layers, dynamat extreme first (sound deadener) followed by Reflectix (radiant heat block, 97% reduction).

http://forums.corvetteforum.com/show....php?t=2066084

To the OP it depends what you're trying to accomplish. I needed 13 2' x 3' sheets of Dynamat ($$$) and one standard roll of Reflectix (cheap) to do the whole interior (minus the doors) of my 79.

They work beautifully together, both heat and sound clearly improved. I expect they would work on their target problems just as well if used independently, although Dynamat does add some heat block. Tedious as anything, but glad it was done.

Best of luck, Steve

 

Reflectix is bubble wrap faced with foil on both sides. If you push a reasonably sharp object into it, like an elbow when you're installing it, you can pop some of the bubbles (I did). But if you distribute the weight over a larger area, like a fakir lying on a bed of nails, there are no issues. I expect with the integrated padding that is part of the DS rug in the front that even where you rest your foot will not be a problem long term. If it needs to come out it peels right off if installed with the foil tape and the 3M spray glue. Nice product and real easy to use.

 

Okay, that's what I thought it was.

I recommend against it for the thickness. Or use it in areas where it won't effect fit and finish.

I know people have had good experience, but I find it annoying when panels bulge and don't fit well.

One note if you go the lizard skin or "micro-spheres" route. Wear a respirator when handling the micro-spheres if making the home version. There is a risk of silicosis. Also, I'm not sure if Hy Tech is still in business, they never responded to my emails. http://www.hytechsales.com/

Google it, there is a lot of info on the micro-sphere thing.

As a side note. People should consider wearing a respirator when doing any type of sand/ media blasting, fiber glass sanding, and whenever they are removing particulate (dust) type stuff from these cars.

 

That makes perfect sense to me, thanks.

 

You may want to go to HomeDepot and take a look at the "Duct Insulation". It can be found in the area near HVAC supplies, and usually the water heaters. REQUEST. If any of you guys that have used hush mat or cool mat or dynamat would take a look at the duct insulation for us cheap bast@#$ it would be greatly appreciated. To me it looks like the exact same thing a dynamat a SMALL!!! fraction of the cost. It comes in a roll measuring 15' by 1' (ie 15 sqft). It is made to insulate HVAC duct. It has the same foil back and foam insulation as the mentioned products. I have used it in attacts, and applied it to extremely dusty ducts with great adhesion. It bends with corners and is rolled into place just like the expensive bretheren. Any comments??? If we dont get any responses, I may make this a new thread. Thanks guys.

 

dynomat extreme....2 boxes... i think 72 sqft......

 

Hey MP,

It's not even close to being the same as Dynamat. The FrostKing HVAC stuff is a foam rubber that is foil backed. As you mentioned, it is intended to insulate through contact (ie non-radiant), not sound deaden. With that, it doesn't have the same efficiency to reject radiant heat that Reflectix does (which is amazingly efficient).

http://www.frostking.com/Lowes/FoamF...Insulation.htm

Again, what's the goal...if you're looking to block the radiant heat sneaking in through the floor/firewall/tranny tunnel Reflectix is a cheap and easy to use option. The foam will likely work, but nowhere near as well. If you're looking to block sound the foam is not the answer.

In many ways sound deadening is a function of holding things together. Dynamat extreme is a dense butyl rubber with a foil face, not a loose foam rubber like the FrostKing stuff. It is thin but incredibly sticky and stretchy. It works by stopping parts vibrating, then distributing any residual vibrations over a large area to make them inconsequential. The cheap foam will most likely not deaden sound because it will not eliminate or distribute the vibrations in the same way.

Dynamt is crazy expensive, even the best deals. If you're looking to block sound it's top notch, but there are other cheaper products out there that are reasonable, cheaper substitutes. The specs are not as good as Dynamat but they are designed to sound deaden. I don't expect the FrostKing stuff will do the job though...minimum would be FatMat or some semi-equivalent butyl prodcut.

As far as the heat block I highly recommned Reflectix. Cheap and easy.

Go for it, Steve

 

heres what i used, worked xcellent
http://www.insulation4less.com/prodex_Ffmf.asp