As muscle car owners, we’re proud of that bass note burble that forces us to shut down at a drive-thru. (“You want what with that cheeseburger?”). Truth is, as authoritative as that exhaust note can be, over time it can get tiresome and actually add to driver fatigue. And if you’ve hot-rodded your engine, the increase in heat can be a problem as well. Without sufficient insulation for heat and sound, your muscle car could end up being a hot and noisy ride, which is an uncomfortable experience at best. That might be kind of fun for a short run, but not on a longer drive.As a case in point, let me share a personal experience. In a previous life I worked for a certain well-known Texas chicken farmer turned racer and sports car builder, who decided to reintroduce the Cobra that he had created back in the ‘60s.
When our factory mule was put together rather hurriedly as a display vehicle, a few key items were left out, such as barrier materials (insulation) in and around the fiberglass cockpit, and a rubber grommet on the steering column where the shaft passed through the firewall. When that 427 big-block V-8 came up to operating temperature, a blast of hot air flowed right between the driver’s legs. While we jokingly referred to this feature as the “Shelby nut roaster,” it made for a really unpleasant driving experience.
Personal comfort aside, high levels of noise and heat can also interfere with your reaction time and driving ability. Not only that, with good insulation, your air conditioner can operate more efficiently (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 muscle car, we sought out some expert assistance from Tim Cox of Quiet Ride Solutions to help with a big-block, ‘64 Ford Galaxie XL. (While not your typical muscle car, the insulation techniques apply to a wide range of vehicles.)
In order to reduce noise, we should point out that sound can emanate from at least two different sources: via a solid material (the frame and body panels) and through the air (such as from the exhaust pipe, and somewhat surprisingly, the air intake).
Lowering airborne noise might require toning down that turbo noisemaker under the hood, which is probably not an option on your muscle car. But as for minimizing vibration-borne noise, the basic approach is similar to placing your hand on the skin of a drum. Flat areas of your vehicle’s sheet metal 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 asphalt, is the rough equivalent of placing your hand on the drumming motion of your vehicle’s sheet metal panels. Quiet Ride, the country’s largest distributor of Dynamat, starts an insulation project by laying down intermittent strips of this self-adhesive material on the sheet metal.
Why not use just one big sheet? Keeping costs down is one reason, and Cox says those individual strips work just as well. Why? Imagine dropping a stone on the surface of the water, forming ripples. Those waves of water provide are the visual equivalent to sound waves, and the Dynamat strips act as breakwaters to attenuate the motion.
A layer of Quality Heat Shield is added next. It’s a dense padding bonded to a reinforced layer of aluminum foil. It’s important that the foil be placed on top, rather than against the sheet metal, for several reasons. It not only serves as a skin to protect the padding, but also creates an air pocket, similar to a double-pane thermal window. It’s partly that layer of air that provides the insulation (sound travels more easily through solids).
We’ve noticed a drop in sound levels of 10 decibels or more, depending on the vehicle speed. While 10 db might not sound like a lot, keep in mind that they are measured on a logarithmic scale, so a decrease of 20 db represents approximately a 50-percent reduction in sound. Under hard acceleration, the level was about the same, but at idle and cruising speed, the sound level became significantly lower, making for a much more pleasant drive on a long haul.
As for reducing temperature, the foil also helps to reflect back heat emanating from the engine and exhaust system. This material acts as a fire retardant and reflects back 97 percent of infrared energy, Quiet Ride claims, resulting in a temperature drop of as much as 30 F. As already noted, this reduction can benefit both the passengers and the engine.
It’s fairly easy to put in the materials, usually in less than a day, and Quiet Ride offers a wide range of pre-cut kits for all types of project vehicles. A universal package that you can custom fit is available as well. The company has just introduced a new type of fiberglass-reinforced foil called WaterShield for door panels, along with molded firewall panels, both of which simplify installation.
It’s important to make sure the materials form a consistent barrier or envelope that’s sealed with foil tape at the seams, and is glued down securely. Otherwise, a small opening might give you a case of cabin fever.
Quiet Ride Solutions
6507 Pacific Avenue, Suite 334
Stockton, CA 95207
www.quietride.com (http://www NULL.quietride NULL.com)