There are a lot of products out there for soundproofing your car but there is precious little "How to" information out there regarding this subject. I am here to fill that void. When soundproofing any vehicle, the first order of business is to take care of the engine noise coming from under the hood. Most people don't realize that a lot of the noise they hear in the passenger compartment of their vehicle is actually being transmitter from the engine and the road via the tires and shocks. In essence these sounds and vibrations are transmitted directly into the hood of the car which is a sheet of steel that simply transmits the noise through the hood I and into the windshield and ultimately to the passengers ears.
I know I know, you have some sort of fiberglass material attached to the underside of the hood, isn't that soundproofing. I'm afraid not, basically that is a heat shield to prevent the heat of the engine from damaging the paint on the surface of the hood. It does work well for that, but it has absolutely no soundproofing abilities at all.
What I suggest is that you remove that fiberglass hood mat and then clean the underside of the hood thoroughly. You will then cut and glue in a piece of 1" America Mat which is a dense vinyl nitrile closed cell foam mat. What you want to do is trace out the underside of the hood using a pencil and butcher paper for example and trace out the cut that you want paying attention to the edges and the contours. How do I cut the foam so precisely you ask? Well I'm glad you asked. The absolute best way to accurately and precisely cut any kind of foam is to use an electric kitchen meat-cutting knife. These electric knives are readily available at Wal Mart or K-Mart and cost about $9- $12. It is well worth the investment if you plan on soundproofing your entire vehicle. Basically you would trace the pattern of the underside of the hood; you can actually cut the America mat to the same pattern as the protective mat that came with the car that way you know it will fit and look properly. Once you have the America mat cut to your liking and the underside of the hood is cleaned down to the paint, I would recommend cleaning the underside with a terry cloth rag and some alcohol. This will insure good adhesion of the adhesive. You can also rough up the underside with a fine grit sand paper on an electric sander. Cover the engine with a towel or drop cloth to prevent adhesive of sand granules from getting into the motor. Now you will spray a good quality contact cement to the underside of the hood as well as to the smooth side of the America Mat. I like the 3M Super 77 spray contact cement. Keep the 2 pieces apart for as long as the instructions say and once the adhesive has tacked you will adhere the foam to the underside of the hood. You will want to use tape to hold the America mat to the underside of the hood until it dries enough to stick on its own. When the adhesive has dried you cam close the hood and drive off. The America mat can withstand temperatures of 240 Deg F and will literally last for the life of the vehicle.
This system can also be used on trucks and motor homes. We have many customers who have used the America mat to soundproof the "Doghouse" that covers the engine from the inside of their coach.
Now there are also materials that can be used for the floorboards as well as door panels and the back areas of station wagons or vans or the trunks of cars. We have also had people with classic cars use the America mat to soundproof their vehicles; it can make your Corvette sound a lot quieter with the top up. I hope this has helped you in your quest for a quieter vehicle. There will be more articles on car soundproofing in subsequent articles, until then, this is Dr. Bob.Out!