In an earlier article, we looked at ways to beat the heat in order to help cool your car or light truck. But that article didn’t cover all of the bases. What if the engine is cooling reasonably well, but exhaust heat is doing a number on things like adjacent wiring or plumbing?

For example, it’s not uncommon to find fuel lines running close to the engine or the exhaust system.

The result is often boiling fuel and vapor lock.

Another issue can include wiring or electrical components positioned closely to the headers or exhaust parts. In some cases, the wiring can degrade or even melt from the heat radiated from the exhaust. Component failure is often the result.

A worst case scenario can be an electric fuel pump that is precariously close to the exhaust system. Here, it’s a double whammy: The fuel is getting heated excessively and the pump, along with the wiring, is subject to failure from excessive heat exposure.

Certainly, it might be possible to re-route hoses and wiring but in many cases, it’s next to impossible. What can you do?

an assortment of heat shield products for an engine
This is just a sample of the products available to beat the heat in your ride. Included in the mix here is a roll of lava rock fiber exhaust wrap, split reflective wrap for hoses and wires, silicone covered heat guard for wires, self-vulcanizing heat tape, and stainless steel header wrap ties. (Image/Wayne Scraba)

Exhaust Wrap

There are all sorts of engine heat mitigation options available online at SummitRacing.com. One place to begin is with header or exhaust wrap. The idea behind wraps is to contain much of the heat inside the pipe. There are a number of different exhaust wraps available. Typically, the materials consist of fiberglass, fiberglass composite, silica filament, crushed lava rock, woven ceramic, and others. The temperature capabilities typically range from 1,200 all the way up to 2,500 degrees F (with a number of temperatures steps between them). Wrap widths range from one inch all the way up to eight inches, and it can be purchased in rolls ranging from 15 to 100 feet.

Some folks feel that header wraps degrade the lifespan of the parent tube. Others claim it’s nonsense. We suspect it all boils down to the material and the condition of the pipe being wrapped.

How effective are these exhaust wraps? According to Heatshield Products, testing has shown an external temperature drop of over 300 degrees between a raw header primary and a wrapped header primary on a Chevy LS engine (testing was done within three to four inches of the exhaust port). Keep in mind results may vary because things like header coatings can also have an effect upon tube temperatures.

By the way, in that same Heatshield Products test, overall underhood temps dropped over 10 degrees when compared to unwrapped pipes.

Hose & Wire Heat Sleeves

When it comes to thermal sleeves & barriers for hoses, you also have a large range of choices. Included in the mix are barriers in specific lengths and barriers that can be cut to length. Some are one piece slip-on tubes while others are joined—either by hook and loop Velcro style fasteners or peel and stick tape. 

a pair of heat shield wire and hose wraps
In order to protect hoses and wiring from heat, these aluminized fiberglass wraps are an excellent choice. As noted in the article, they’re available in all sorts of different diameters and lengths. (Image/Wayne Scraba)

In order to get a tight fit over a hose end, the split examples are likely the most convenient. Some of the examples are sewn and bound on either end of the tube, and as a result, they’re not easily cut to size. Instead, they should be ordered to fit the appropriate hose length for your car.

man opening a heat shield wire hose wrap
This is what the aluminized fiberglass wrap looks like opened up. These examples are eventually fastened with tape. (Image/Wayne Scraba)

Common lengths run about six inches and up. Diameters range from less than a quarter inch all the way up to five inches. In terms of materials, they include crushed lava rock, woven fiberglass, aluminized woven fiberglass, woven fiberglass with a silicone sleeve and more. Many of these materials are actually fireproof. The aluminized examples reflect roughly 90 percent of the heat they encounter. In terms of heat protection, the various sleeves run from just under 400 to over 2,500 degrees F.

What about protection for wires and wiring harness assemblies?

Much of what applies for hoses applies to wires. But the configurations can obviously change. Here the wiring runs can prove smaller than hoses, and you might be in a place where access is limited (for example, protecting a spark plug wire that has already been terminated).

There are electrical wire heat sleeve solutions for dilemmas such as this.

For example, you can purchase small diameter aluminized sleeving in half inch, three-quarter inch, one inch, and larger sizes. It is sold in various lengths, and it’s very easy to cut.

Another interesting solution is DEI Fire Wrap. Here, heat resistant fiberglass braiding is wrapped with an extremely high temperature resistant iron oxide silicone. It can withstand temps up to 2,000 degrees intermittently and 500 degrees constant. Fire Wrap can be purchased in rolls or in pre-made segments. It’s available in a tube configuration or split with a Velcro closure.

MSD offers a similar product with its Pro-Boot Guard that is used to protect ignition wires. FYI, we use this product to protect starter wires that run alongside the cylinder head and block too.

man holding msd spark plug boot guard heat wrap
There are several different companies offering a version of thermal wrap, including DEI. MSD’s version is shown here. This product consists of heat resistant fiberglass braiding wrapped with an extremely high temperature resistant iron oxide silicone. It’s perfect for wiring harness assemblies. (Image/Wayne Scraba)

Remember the Right Thermal Shield Fasteners

When fastening various heat shield products, it quickly becomes apparent you just can’t use common zip ties or electrical tape. That’s where stainless steel locking ties come into play. They work much like a conventional zip tie, but of course, they’re made of a much more durable stainless steel.

You can get these stainless header wrap ties in all different lengths. You can even buy them powdercoated black if you prefer a stealthy look.

a bag of summit racing steel exhaust wrap ties
Remember, you’ll need steel zip ties that are perfectly suited for securing exhaust heat wraps. I use these stainless steel locking ties from Summit Racing. (Image/Wayne Scraba)

Heat Resistant Tape

It’s also possible to use heat resistant tape in certain locations. This tape is available in several different widths and colors. Essentially it is a foil based tape with some examples capable of withstanding constant temperatures up to 850 degrees F.

Another option is black fire tape. Black fire tape is self-bonding and self-curing. Once wrapped over itself, it forms a solid bond. It can withstand temperatures up to 500-degrees constant. It is perfect for wiring harnesses exposed to heat.

Moroso even sells a version that works as a replacement for spark plug boot shrink sleeves (which often melt adjacent to a header tube).

***

As you can see, there are all sorts of different options to “beat the heat” under your hood—and we’ve only skimmed the surface here. SummitRacing.com is jammed with products designed specifically to keep heat away from sensitive hardware.

Check out the pics below and we’ll show you how easy it is to work with wraps and other heat protection products:

scissors cutting engine exhaust heat wrap
When working with exhaust wrap you’ll find the ends quickly fray as soon as the roll is opened or the wrap is cut. (Image/Wayne Scraba)
man holding exhaust heat shield wrap prior to cutting
To prevent excess fraying, some folks fold it as shown here. There are several other solutions too. (Image/Wayne Scraba)
exhaust heat shield end wrapped with electrical tape
One solution for fraying is to wrap the end with heat tape as shown here, while another is to paint the end with VHT Flameproof header paint. (Image/Wayne Scraba)
starting a heat shield wrap around an exhaust header tube
Here’s how the wrap begins using the heat tape method. For this application, the tailpipe is wrapped over the kickup only. (Image/Wayne Scraba)
wrapping exhaust header tube with heat shield wrap
The tape is wrapped over itself. You can work with less overlap than shown. It makes for less bulk. (Image/Wayne Scraba)
a bent section of exhaust tubing with heat wrap
The sample wrap looks like this. This sample piece was done dry, but it’s possible to do a neater job if the exhaust wrap is wet (or at least damp). Some folks use a water spray bottle to keep it damp during the wrap process. (Image/Wayne Scraba)
wrapping a lock tie around a heat shield wrap
The stainless ties work just like the ordinary nylon ones, except they’re metal. And just like nylon examples, you’ll need to double these up—slide the male end into a second female tie to double the length. (Image/Wayne Scraba)
a bent section of header tube wrapped and locked
This is the completed wrap job, secured at both ends with stainless ties. (Image/Wayne Scraba)
heat shield wrap next to a piece of automotive hose
Here’s a sample piece of thermal wire/hose wrap we’re using to protect a fabric braided AN hose. (Image/Wayne Scraba)
cutting a section of heat shield hose wrap
The aluminized fiberglass heat wraps cut easily with proper scissors. (Image/Wayne Scraba)
an automotive plumbing hose wrapped in a heat shield
Peel the cover from the tape and fasten as shown. As you can see it covers the hose neatly. This wrap is equally at home on wiring harness assemblies too. (Image/Wayne Scraba)

Keywords
exhaust, heat, shield, thermal, Wrap
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Author: Wayne Scraba

Wayne Scraba is a diehard car guy and regular contributor to OnAllCylinders. He’s owned his own speed shop, built race cars, street rods, and custom motorcycles, and restored muscle cars. He’s authored five how-to books and written over 4,500 tech articles that have appeared in sixty different high performance automotive, motorcycle and aviation magazines worldwide.