The internal combustion engine gets hot. With operating temperatures ranging between 90 to 105°C with everything working as it should, and internal temperatures reaching up to 2000°C, popping up the hood on a hot summer afternoon after a decently long drive won’t provide for the best experience. You’ll feel the heat instantly, with some parts radiating more heat than others. This is particularly true of modern cars, where lower displacement has been offset by the use of turbos. These and the exhaust manifolds are the engine parts literally taking the heat from the combustion process.
If you’re building an engine from the ground up, mixing and matching parts can produce interesting results when it comes to heat management. If power output is increased, so is heat. An upgraded cooling system, including radiators, pumps, fans, hoses and expansion tanks will keep everything in working order. If your engine produces excess external heat, surrounding areas, like the hood, wiring, fluid lines and tanks, and side and underbody panels will bear the brunt and may distort or even catch fire. Thankfully, simple and relatively cheap products in the form of high-temperature heat shields dissipate heat buildup in areas where it is needed.
Types of Heat Shields
To absorb and reflect heat radiating from nearby engine parts, various types of heat shields can be used. This includes ‘peel and stick’ and sheet heat shields.
Peel and Stick heat shields are composed of materials with high heat conductivity like silver, copper or aluminium, forming the outer layer, heat resistant polyester reinforced fibreglass making up the core, and self-adhesive backing. Depending on the intended use, heat shields with thinner outer layers of high heat conductive metals, up to 0.05mm thick are used in applications needing more versatility, meaning the thin layers form easily around anything with uneven or irregular surfaces, like batteries, hood lining, airboxes etc. For flatter surfaces or parts generating more heat, a thicker outer layer of 0.25mm will absorb and reflect heat better. Such areas include exhaust manifolds, transmission tunnels or any part of the engine with excess heat. Both types of shields are 3mm in thickness, form easily around the heat source and thanks to the pressure-sensitive adhesive, stick to any surface.
Using a peel and stick heat shield has its upsides. It is extremely thin and engineered for use in tight areas. It is formed easily and sticks well on the heat source. Its fibreglass core will resist temperatures up to 250°C, meaning surrounding areas remain cool to the touch. Before applying, a good idea would be to clean the surface needing shielding so the adhesive can do its work. Peel and stick shields can be used both in the engine bay or outer areas like covering fuel lines, transmission tunnels, floor pans, steering parts and body shields.
Sheet Heat Shields usually come in the form of 3mm aluminium sheets and are used in areas where there is intense heat buildup. Aluminium is used for its heat properties – it has high heat conductivity and reflects heat up to 650°C before it starts to distort and melt. It is also resistant to corrosion. Alternative, but more expensive sheets are made of copper. Aluminium sheets come in different sizes and are formed by making a template around the part needing shielding. They are easily cut with scissors or tin snips, then shaped and drilled into place. The sheets are spaced at small distances, roughly 10mm, from the shielded parts to avoid melting. Common areas where aluminium heat shield sheets are used are firewalls, around turbines, exhaust pipes, and enclosures around air filters.
Other Heat Insulation Products
Besides peel and stick, and sheet heat shields, there are other insulation solutions. This includes under-bonnet insulation that is used both as a heat shield and for sound insulation. They deaden loud engines, will also providing protection from heat sources that can potentially damage the hood. Under bonnet insulation is made of durable polyester fibre and has an adhesive lining that sticks to the inside of all hoods. It doesn’t deform, has resistance up to 200°C, and won’t catch fire. A sound solution if your bonnet lining is damaged or your car doesn’t have one.
In addition, you can use exhaust wrap that fits around hot exhaust header pipes for better exhaust flow. These are titanium-coated layers. There are also complete aluminium exhaust pipe kits that are pre-formed to fit and include mounting brackets and bolts. Both are used to reduce heat radiating into the floor pan and the cabin.
Using Heat Shields
Heat shields and insulation wrapping not only shields surrounding engine and body parts from overheated components but also play a major role in engine longevity and performance. By providing optimal temperatures, especially around air intakes, they help the engine with cool air, consequently offering better compression and combustion – meaning better overall performance. An overheated engine is an overworked engine, and parts will wear sooner. Simple solutions like heat shields pay off in the long run and are cheap and easy to use. You can buy heat shields and insulation products from stores specialising in car tuning and rebuilding. Most will also have online stores that you check out.
