Heat is the number one killer of all vehicle components, especially electronics and moving parts. Under the hood of your car, is a giant heat-generating engine, so reducing the radiant heat under the hood not only helps required components last longer, but also helps increase the performance of your engine. The cooler the air charge going into the engine, the denser it is, meaning more potential energy.
One of the best ways to reduce heat under the hood is with exhaust heat wrap. Exhaust heat wrap insulates your exhaust manifolds (or headers), keeping the heat inside the exhaust, where it moves much faster, and reduces the radiant heat that kills components and heats up the incoming air charge for the engine. This is done through two principles- the first is insulation. Just like a coat, the wrap contains the heat inside the tubes. Using a base fiberglass weave along with proprietary materials, exhaust wraps can reduce underhood temps by as much as 50%. Considering that for every degree of temperature drop engine performance can increase by 1%, this is a serious potential performance gain. The second principle is through thermodynamics of gasses. Hot gasses move much faster than cold gasses. Wrapped exhaust keeps the heat inside the exhaust, keeping the gasses heated further down the pipe. This keeps things moving faster, which actually helps draw more fuel and air into the combustion chamber for the next charge. This is called scavenging, and increasing this value always leads to more power.
Installing the wrap is the trickiest part, especially in the tight bends. There are few tricks to make this easier as we have illustrated below. We took a set of custom-made headers and a downpipe for a turbo engine to show you the process of installing exhaust wrap. Once you get the first piece done, the next one is that much easier.
Tips and Tricks
Most exhaust wraps loosen up a little with some water. You can use a squirt bottle or simply soak the wrap in water and squeeze out the excess. This helps the wrap stick to itself a little better. When it dries, the wrap will hold its shape a bit better as well.
Large simple pipes are easy, but when it comes to headers; you need an extra set of hands to get the job done. Tight bends and intersecting pipes make headers pretty tricky, a second set of hands is helpful to hold the headers while you pull and stretch the wrap around the pipes.
Another issue with headers is the intersections of pipes. You can’t wrap a header or manifold with a single piece of wrap, you need to wrap each smaller tube and then wrap the larger tube to incorporate the wrap over the smaller pipes. Tape keeps the wrap secure until you get the overwrap complete. Remove the tape right before the joint is overwrapped.
Exhaust wrap is secured with stainless steel ties, these are not cheap and they are not removable. The first header is often good practice for the second one, where you might find a better method. For this reason, we suggest that you don’t secure the first piece with the ties until after you have finished the second header, you may decide to re-wrap the first one. This comes from experience.
Exhaust wrap adds thickness to the pipes, so in vehicles with really tight clearances, you may want to check the fit of the parts before securing the ties. We have found that a re-wrap is sometimes necessary to gain the proper clearance.
Proper wrap requires a good 1/2-width overwrap. This yields plenty of coverage and minimizes buildup.
If you follow these steps and have some patience, your exhaust wrap job will last a long time and help keep those underhood temps down. Don’t forget to secure the wrap with the stainless steel ties once you are satisfied with the results.
Check out all the exhaust system products available on NAPA Online or trust one of our 17,000 NAPA AutoCare locations for routine maintenance and repairs. For more information on exhaust heat wrap, chat with a knowledgeable expert at your local NAPA AUTO PARTS store.
A life-long gearhead, Jefferson Bryant spends more time in the shop than anywhere else. His career began in the car audio industry as a shop manager, eventually working his way into a position at Rockford Fosgate as a product designer. In 2003, he began writing tech articles for magazines, and has been working as an automotive journalist ever since. His work has been featured in Car Craft, Hot Rod, Rod & Custom, Truckin’, Mopar Muscle, and many more. Jefferson has also written 4 books and produced countless videos. Jefferson operates Red Dirt Rodz, his personal garage studio, where all of his magazine articles and tech videos are produced.