? about DYNAMAT

[Tom Welch]

Ok, here goes nuthin' I have found some interesting info on sound insulation. It goes like this. In order to stop sound from coming into the cabin of a vehicle there are a couple of options for effective insulation. First, insulate the firewall from the engine compartment side. This is the correct way to do this. A foil facing with 1/4" foam then a noise barrier (solid layer 1/8" thick, like hard rubber) then about 3/4" sound absorbing foam, this is 1 effective way to seriuosly dampen interior noise. Another is to start with reinforced foil facing on the noise barrier which covers 1" of sound absorbing foam. This looks real good, would make a really neat firewall. The second option is to insulate from the inside starting with some vibration damper. I dont recommend covering the whole car with this type of product, just about half of the interior, evenly spaced pieces, works just as good. Less expensive, too. Aluminum faced high temp foam with or without a psa works very well here. On the under side of the body in strategic areas apply a heat shield, aluminum faced fiberglass or silica matting. Also nonwoven material in the form of fiberglass or silica with 9 micron sized fibers, (non-respirable) can be used inside the cab to insulate effectively against heat provided that aluminum is on both sides of the mat. I have read several articles about how some rod shops do this. They follow the looks is better than function school. It seems like that anyway. Using Lizardskin first then a heatshield and then foil covered jute is just plain wasteful. The Lizardskin dampens vibration, put this on the inside of the car first, then the foil covered jute. Put the heatshield where it will do something. on the firewall or under the floor between the floor and exhaust. Logic works, looks are fine but performance trumps looks anyday, especially after the upholstery is in place. In order to have a nice smoothed firewall, care must be taken to avoid ineffective insulation application. Most insulation for sound deadening is made to go in the engine compartment area, hence the aluminum facing for heat reflection. The foam absorbs sound waves, the sound blocker does just that, blocks sound waves, reflecting them back at the source. Put on backward it does almost nothing. The products used inside the cab have a different composition and a layered approach is needed. This is what most people already do, but with incorrect products for the application. Foam works inside the cab very well if made for the interior of a vehicle, carpeting over the foam, fiberglass, jute, whatever, adds a little more. One thing I have found to be true for me. A quiet car isn't hot and a noisy car isnt cool. I recommend an aluminum facing for durability and to keep moisture out. I believe the best way to thermally and acoustically insulate a car is to use a heat shield on the firewall and above the exhaust, then vibration damper on the interior floor and doors and other areas of vibration. Topped with a heat resistant foam about an inch thick with a foil facing. This should prove effective for most applications. Double the foam on the firewall interior if needed to absorb the noise. More to come.