Muscle car enthusiasts expect their rides to by hot and noisy. After all, that’s not a sewing machine under the hood. On the other hand, while rumblin’ and roarin’ can be great fun for a short run, it can get pretty tiresome on a longer cruise.
Personal comfort aside, high levels of noise and heat can also interfere with your reaction time and driving ability. On the other hand, with good insulation, your air conditioner can operate more efficiently (thus reducing fuel consumption and the risk of radiator boil-over). Also, your audio system should have better fidelity.
To see what’s involved in reducing sound and heat in a street rod, we sought out some expert assistance from Tim Cox of Quiet Ride Solutions who recently insulated a Hemi Dart (featured elsewhere in this issue). Whatever type of muscle car you own, the principles of sound and heat shielding apply to just about any type of vehicle.
Drawing on Cox’s advice and experience, let’s address the noise aspect first. Note that sound can emanate from a least two different sources on a car: via a solid material (the frame and body panels) and through the air (such as from the exhaust pipes, and somewhat surprisingly, the air intake as well).
Lowering airborne noise might require toning down that noisemaker under the hood, which is simply not an option on a muscle car (we don’t want to spoil all the fun here!). However, to minimize vibration-borne noise, the basic approach is similar to placing your hand on the skin of a drum. Flat areas of sheetmetal produce the most sound, so those need the most attention, but the entire cabin area should be insulated wherever possible.
Installing Dynamat, a material composed of rubber and aspalt, is the rough equivalent of placing your hand on the drumming motion of your rod’s interior body panels. Quiet Ride Solutions, one of the country’s largest distributors of Dynamat, starts an insulation project by laying down individual strips of this self-adhesive material, or a solid sheet if preferred. (Cox feels the strips work just as well in most cases).
Next goes on a layer of Quality Heat Shield, dense padding bonded to a reinforced layer of aluminum foil. It’s important that the foil be placed on top (instead of against the body panels) for several reasons. It not only serves as a skin to protect the padding, but also creates an air pocket, similar in to a double-pane thermal window. It’s that layer of air that provides the insulation (sound travels more easily through solids).
As just one example, Cox recalls a hot-rodded ‘64 Chevelle that he insulated. Prior to adding the materials, at 60 mph the sound level was 100 db (equivalent to that of an unbridled jackhammer, he says), but afterward, it dropped to 80 db. Ditto for the levels at idle (80 and 60 db, before and after). That’s a huge difference, especially when you consider that decibels are measured on a logarithmic scale, so this decrease represents approximately 50 percent reduction in sound!
As for reducing temperature, the foil also helps to reflect back heat emanating from the engine and exhaust system. This material acts a fire retardant, and reflects back 97 percent of infrared energy, Quiet Ride claims, resulting in a temperature drop of as much as 30 degrees. As already noted, this reduction can benefit both the passengers and the engine.
It’s fairly easy to put in the materials, and Quiet Ride offers a wide range of pre-cut kits for cars, trucks, RVs and other projects. In case your particular muscle car’s patterns aren’t available, universal package that you can custom fit is available as well. Which means you can make the inside of your muscle car both cool and quiet.
Quiet Ride Solutions
6507 Pacific Avenue, Ste. 334
Stockton, CA 95207
This decibel meter showed an immediate drop in sound level after installing just the insulation. Once the interior is re-installed, the noise level should be reduced even more.
Prior to installation, lay out the pre-cut pieces of Dynamat throughout the interior to get an idea of where they’ll fit. (Don’t forget the headliner as well—determine the position of those strips by laying them on the rooftop). The blue tape covers the self-adhesive side, so these strips will be turned over later on and pressed in place after determining their correct location.
The blue backing tape peels back to expose the self-adhesive side of the Dynamat.
Use a roller to press the Dynamat strips in place, so they bond tightly with the sheetmetal.
This closeup shows the Quality Heat Shield’s reinforced aluminum foil and dense fabric padding. The foil side will be installed facing up.
Dry-fit the pre-cut pieces into place before applying adhesive.
Spray adhesive on the underside of the padding. A double application on the edges is a good idea to ensure a tight bond.
After adhesive is applied to both surfaces, lay the Quality Heat shield on the Dynamat strips.
Be sure to apply foil tape to all seams to create a consistent barrier, with no gaps.
Quite Ride’s offers both universal (shown here) and factory pre-cut kits. Each includes include Dynamat strips, Quality Heat Shield, spray-on adhesive and foil tape. If you have a custom buildup project that requires the universal kit, electric scissors should make the cutting job much easier.