Almost anyone with headers on their car or truck has experienced burned spark plug wires and has melted through a spark plug boot or two. This article will help you pick the best spark plug wire heat shield sleeves, guiding you through the maze of options so that you can make a choice that is both cost-effective and just plain effective at saving your spark plug wires from heat damage.

Let’s look at the types of potential damage and the associated costs from when hot exhaust and spark plug wires share close quarters. Obviously, you have the cost of replacing said wires, which in race applications could mean an expense of more than $100. Not so obvious, though, is that when a spark plug boot melts, it could create an ignition misfire/no-fire problem. That could cause you to lose a race or end up stuck on the side of the road, and it could potentially cause engine detonation due to a buildup of unburnt fuel in various cylinders and intake runners.

Complete burn-through is not the only problem that heat could cause with spark plug wires and boots. Whenever a wire that conducts electrical energy is exposed to high heat, the resistance of the wire increases. That means it takes more time for the energy to travel through the wire, and a certain amount of the energy is restricted and never reaches the spark plug.

The benefit of thermal-barrier spark plug boot protectors is that heat-induced electrical resistance will be reduced significantly, meaning your ignition system won’t have to work as hard, and the full spark energy will be delivered to the spark plugs. Heatshield Products offers several thermal-barrier products designed to protect spark plug wires and boots from heat damage. Which one to use in your application will depend on the type of engine you have, how much heat is produced and what type of damage you need protection from.

Insul-Boots™ are made from a conventional thermal-barrier material with a special coating that helps reflect heat. To keep the boots in place, there’s an innovative Heatshield Products ring that goes between the cylinder head and the tip of the boot. Without it, the boots will walk up the wire over time, exposing the spark plug boots to the heat you’re trying to protect them from. Insul-Boots™ can withstand temperatures of 1,200-degree Fahrenheit constant and 2,000-degree intermittent, and they are available in a variety of colors.

Lava Boot Shieldsare a dual-wall design similar to the Insul-Boots™, but are made from a unique high-temp basalt material, so they are very flexible. The material also expands and stretches, making it easy to install over straight, 90-degree or 135-degree boots. Lava Boot Shields™ also include the Heatshield Products rings to hold them in place on the spark plug buts. They can withstand temperatures of 1,200-degree Fahrenheit constant and 2,000-degree intermittent.

HP Boots combine 304 stainless steel and ceramic insulation to reflect heat and to provide a heat barrier for extreme conditions. They are not very flexible, so we make preformed straight and 90-degree and 135-degree configurations. HP Boots™ can withstand constant 1,800-degree temps and up to 2,200-degree intermittent temps. HP Boots™ will not slide up the spark plug but, and no ring is needed to keep them in place.

HP Color Sleeve™ is ideal for a spark plug wire protector beyond the spark plug boot. The weaved sleeve expands and contracts to install over assembled spark plug wires. It is sold in a 25-foot roll with 16 heat-shrink pieces to cleanly secure the ends of the sleeve to the wire. It is available in a variety of colors and is rated for temperatures of 1,200-degree Fahrenheit constant and 2,000-degree intermittent.

A typical street engine with headers will normally have between 300 and 500 degrees at the header tube closest to the spark plugs. Under hard load, this temperature can double, but our Lava Boot Shields™ can still manage the heat. However, for higher horsepower engines or supercharged/turbocharged applications, the normal exhaust temp can be much higher, making HP Boots™ the better choice.

We also know that you don’t normally need protection on every spark plug boot. That’s why our Insul-Boots™ and Lava Boot Shields™ are available in sets of 2 or 8, and our HP Boots™ are available individually.