Hot rods started as a pretty basic notion of taking an inexpensive car that could be found just about anywhere, like a 1932 Ford, cut some weight out, lower it and maybe chop the top to get better aerodynamics, and soup-up the engine.

Of course these early rods needed to sound as good as they looked, so many of these rods ran open headers or cut-outs for that really aggressive rumble and pop. Hot rods were about performance and sounding like a rebel.

This was a great form of self-expression and an exercise in breaking existing rules, but even chicks that love bad boys eventually realized that they wanted to cruise in comfort. Noise levels that are “particularly bothersome, extremely unpleasant,” or “objectionable,” could kill a romantic drive down the local crusin’ strip. We can still build badass hot rods, but with help from Boom Mat, we can also control the boom.

What’s It All About?

Hot rods are supposed to be fun, and the hobby started out that way. Somewhere along the way we all figured out that we could put a nasty big-block with huge pistons slapping away in their bores, but didn’t have to suffer with a sound that is similar to being inside a submarine while the tin benders are pounding rivets into the hull.

Watch How Boom Mat Works To Stop Vibration:

Design Engineering Inc. (DEI) is the parent company behind Boom Mat acoustical products, which is an industry leader in helping car builders filter sound and eliminate unwanted noise in vehicles’ passenger compartments. Not only do these products remove offensive noise, Boom Mat simultaneously dampens vibrations in the sheet metal caused by road rattle, engine noise, or bass vibrations from audio equipment. All of this allows the driver and passengers to enjoy the sound waves that they would rather hear.

DEI is very specific about how to use their products to get the most benefit. To get the details about the Boom Mat products, we contacted DEI’s Mike Zenone, Boom Mat Brand Manager. “What makes Boom Mat special is the breadth of the product line,” he said. “We have a very expansive product line extending from vibration damping materials, sound absorption materials, sound barrier materials, thermal insulating materials, speaker baffles to a spray on Boom Mat damping product. Our product line is not a one or two trick pony.”
Watch The Boom Mat Installation Video Here:

Where Do You Start?

According to Zenone, the first place to start is with the Boom Mat damping material that comes in 12-inch by 12 1/2-inch and 12 1/2-inch by 24-inch sheets of pure butyl rubber. Butyl is odorless and probably tasteless material, however, we did not do a sample test to confirm the taste. We do know that scientific studies show that butyl has excellent impermeability, and the polymer makeup gives the material great flexibility.

“You don’t need to cover every square inch,” he cautions. “ We recommend 25 to 50 percent coverage. You can go as high as 75 percent if you want to go crazy. We’d love to see you buy as much as you want, but we also see a bigger picture here.” Zenone’s point is to use only as much as you need to do the job and be cost efficient.

“You don’t have to make sure that each piece butts up against each other. This product was made for those wide expansions of sheet metal like roofs, trunks, floorpans and doors. Basically any flat sheetmetal without bead rolls or supports.”

Zenone recommends checking for sheet metal areas that are prone to acoustic vibrations by tapping on flat areas with your knuckles. He says that you will hear the spots that are most prone to vibration.

The misconception is that you buy the material and you have to cover every square inch with it. “Vibration damping material is designed to add mass to sheet metal to take care of that structure-born vibration,” he said, “That vibration you get driving down a bumpy road. This will help with all the rattling and squeaking.”

The Boom Mat damping product is a peel and stick sheet that is comprised of two layers. “The black butyl layer comes in either 2 mm or 4 mm thickness with a 4 mil foil layer,” he added. “Most of the damping material on the market are 1.5 mm with a 3 mil foil layer.”

There is more than meets the eye when it comes to the product. “Many manufacturers use an asphalt based material,” Zenone stated. “Asphalt burns, butyl does not. Boom Mat is actually self-extinguishing. Asphalt materials get soft at higher temperatures and typically have less adhesion, especially on overhead surfaces like the roof.  Butyl is super sticky with high adhesive properties, so temperature inside the car is not an issue. Plus, it doesn’t off-gas like asphalt.” Great vibration damping with strong adhesion and no odor sounds like a great deal to us.

Watch The Tw0-Step Process Here:

The Workhorse

After the vibration damping material has been applied, the next step is to lay the Under Carpet Lite, a sound absorption and thermal insulation product. “This is the workhorse,” said Zenone. “It is a lightweight fiberglass multilayer composite that is just under a half-inch thick, and compresses down to a quarter inch thick. To get the most bang for your buck, apply it full coverage, from firewall, floorboards, rear decks, to tucking it under your headliner for great sound absorption and thermal insulation.”

According to Zenone, the Under Carpet Lite was tested with a torch on one side to over 500 degrees, while the other side stayed at room temperature. The multi-layered product is super lightweight,  extremely flexible and easy to install. Referred to as UC Lite by the company, the thermal padding helps provide less heat transfer in the summer and protects against the transfer of cold air in the winter.

“The UC Lite can be used alone, or with the Boom Mat vibration dampening material,” said Zenone. “It can be mechanically fastened to the area or tacked in place with our Hi-Temp Spray Adhesive. It really takes two steps to sound deaden and insulate a vehicle though, and using both products is highly recommended.”

Testing

Testing done at the factory showed a significant improvement in sound testing results. Zenone told us that in real numbers, the drop in decibels after soundproofing is about six to ten decibels. “While that doesn’t sound like a lot, it is really a drastic reduction in noise level,” he stated. “A four to six decibel level drop sounds 25 percent quieter. When you are talking about eight or nine decibels, that sounds 50 percent quieter. That is significant.”

A significantly quieter cockpit for a 1932 roadster is a big deal. When you can have a hot rod, and have the comfort of a luxury car, that represents the best of all worlds.

For more information about Boom Mat or DEI’s lineup of Boom Mat products, visit them online at www.designengineering.com