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Exhaust System Insulation

Wrap it up

It can get pretty warm under the hood of a car. The engine gets plenty hot, and the radiator gives off heat as well. If you have performance equipment like a supercharger or a turbo, you're in for some extreme temperatures. This heat causes many problems, like drying out gaskets and premature leaks in coolant and vacuum systems. Heat also "cooks" sensors and electrical equipment, and can cause discoloration and peeling of metal and painted surfaces. Not to mention burned hands from groping around for dropped tools!

Play It Cool

How can you minimize or even prevent these problems, especially on a car you've worked hard to restore? One of the best ways to lower the temperature under the hood is to insulate the headers. A few different methods can be used, such as using a special coating or a chemical heat-treating process. Or you can wrap the headers and exhaust system with heat-absorbing tape made specifically for this purpose. One manufacturer claims that in addition to reducing heat, installation of the wrap will even produce more horsepower by preventing the power charge leaving the cylinder head from cooling off too quickly (which otherwise might result in a loss of velocity and scavenging efficiency).

Installing header wrap isn't difficult, but there are a few tricks that make it go easier. Note that the first time you start the engine the freshly painted wrap will smoke heavily for five minutes or so. Heat wrapping your headers is a 2-3 hour job, not counting drying time. Once installed, you will find your engine area to be a much cooler place, and you might find you have more power as well. And more important for a resto project, you won't see all that hard work and those expensive parts go up in smoke.

Tools

You will need enough wrap to cover your headers. For a typical small-block V-8 engine, this means two packages of two-inch wide, 50-foot long wrap (or one 100-foot roll), a box of snap wraps (an ultra-thin stainless-steel perforated metal strap) or hose clamps and an aerosol can of high-heat coating. Big-block V-8s need another roll of wrap, and 180-degree headers can take three rolls or more. The wrap also comes in a one-inch width for working around small-diameter convoluted headers. You'll also need a pair of gloves, since the wrap is a fiberglass-like material, and can irritate your hands as you are installing it.

Start by measuring the length of each header tube from the flange to the first junction where you can't wrap the tape around the tube anymore. The instructions will tell you how much material is needed, determined by the diameter of your header tubes. For instance, a 1-3/4-inch diameter primary pipe will require 88 inches of wrap per foot of length. Add an additional eight inches for each bend in the tube. Do the math and cut your first length. This is not an exact science, so cut one piece at a time and apply before cutting your other lengths. You may need to fine-tune the recommendations to suit your application.

Prep

The wrap is too stiff for applying when dry, so dampen it in a shallow pan or dish before you start wrapping. Don't soak it, though. Just a quick dip is enough.

Start by wrapping your first length around a header tube at the flange. Use a snap wrap or hose clamp to secure it. Snap straps are handy in tight locations where a hose clamp would be in the way of spark plugs or header bolts, but hose clamps are easier to install. As you wrap the tube in a spiral fashion, overlap the layers by a quarter-inch and pull tight.

Finish

Snap-Strap, an ultra-thin stainless steel perforated metal strap, comes in a roll and is cut to length. Wrap the strap around the tube, slip the two ends of the strap through the barbed bracket and pull it tight. A small pair of needle-nose pliers is handy for twisting the ends back (like opening a sardine can).

Wrap each primary tube down to the collector, secure the bottom end with a strap or clamp, and then wrap the collector. The tricky part is getting the wrap into the tight crevices between the tubes. If necessary, use a screwdriver to carefully pry the tubes apart. The objective is to cover all metal areas with wrap, right down to the outlet flange. Dry the wrap out by putting the headers out in the hot sun, or use a hot lamp to help cure. As it dries the wrap becomes harder. Once dry, spray with Hi-Heat paint, which seals the pores and protects from moisture.