Tag: insulation for vehicles

The best automotive heat shield material depends on what you are protecting and how close it sits to the heat. A thin gold foil sheet is right for an airbox and wrong for a floor pan. A 5mm insulated sheet is right under the car and too bulky for a tight firewall gap.

This guide compares the materials first, then maps each engine bay part to the product that suits it. Every sheet and panel is in the Kool Wrap heat shield range.

Automotive heat shield materials compared

Choosing the best heat shield material for the job

Two questions settle it. Does the shield stick to the part you are protecting, or stand off the heat source? And how much room do you have?

Adhesive shields bond to the panel or part you are protecting. Thicker sheets insulate more but need more clearance. Semi-rigid panels mount near the heat source itself with brackets or hose clamps and suit places where there is no clean flat surface to stick to.

Neither goes directly onto an exhaust pipe, manifold or turbo housing. Kool Wrap does not publish a temperature rating for the adhesive, so the sheets stay on the panels around the heat. To cover the pipe itself, use exhaust heat wrap.

Source or target: where to start

There are two ways to control heat. Containing it at the source, with wrap on the headers or a blanket on the turbo, lowers radiant heat across the whole engine bay. Protecting the target, with a shield on the firewall or a sleeve on a loom, helps one part at a time. Most builds need both. Treat the hottest sources first, then fill the gaps.

Exhaust manifold and headers

On most engines the headers radiate more heat into the bay than anything else. Exhaust heat wrap keeps that heat inside the pipe. Pick the wrap by the heat it will see:

• Standard fibreglass: 540°C continuous
• Vermiculite coated fibreglass: 650°C continuous
• Titanium basalt fibre: 980°C continuous, for the hottest jobs

Paint mild steel headers with high-temperature exhaust paint before you wrap. Leave O2 sensors and flex joints uncovered. Do not use adhesive heat shield or foil tape on the headers. Neither is made for direct exhaust contact.

Turbo

A turbo blanket keeps heat in the turbine housing instead of letting it radiate onto the intake, intercooler piping, hoses and wiring. Titanium basalt and silicone coated blankets use 12mm of internal silica insulation and a stainless steel mesh inner, and fit with stainless mounting springs. Choose titanium basalt where heat is highest, silicone coated where oil and fuel are around, or carbon fibre for an ultra-high temperature rated option. Measure your turbine housing before you order. See the turbo blanket range for sizes, and what a turbo blanket does if you are still deciding.

Dump pipe and front pipe

The dump pipe carries exhaust gas straight off the turbo and often runs close to the firewall. Wrap it with titanium basalt or vermiculite wrap and lock it down with stainless steel ties. Where the pipe runs close to a panel, add a reflective shield on the panel side as well.

Firewall

The firewall takes radiant heat from the headers and turbo and passes it into the cabin. Stick a flexible adhesive shield to the engine side. The 1.5mm silver adhesive heat shield has heavy duty aluminium foil over a fibreglass backing rated to 593°C, and cuts with scissors. Where space is tight, the thinner 0.5mm Gold Reflecta Shield gives you less bulk. Cut around wiring grommets and the steering column rather than covering them.

Intake pipe and airbox

Cooler air around the intake means the engine draws in less heat with it. A reflective face on the airbox and intake tube limits the heat the air picks up on its way to the engine. Stick Gold Reflecta Shield or 1.5mm silver sheet to the airbox. For round intake tubing, wrap fibreglass-backed aluminium tape around the tube. It reflects 95% of radiant heat and withstands up to 454°C radiant heat.

Wiring, hoses and sensors

Looms, vacuum lines and rubber hoses near the exhaust go brittle and crack. Slide a heat sleeve over them. Sleeves come in open seam and closed seam versions, so check the product pages for the one that suits your loom. For short runs and joins, the heat resistant tape range includes reinforced foil tape made for wrapping hoses and wiring. Our guide to protecting cables, hoses and sensors from engine heat goes into more detail.

Fuel lines

Hot fuel lines can cause vapour problems and hard hot starts. First, route the line as far from the exhaust as you can. Then sleeve it or wrap it with reflective tape. On a fuel tank face near the exhaust, use an adhesive shield on the tank side.

Starter motor

Starters mounted beside the exhaust suffer heat soak, which shows up as a slow crank or a no-start when the engine is hot. Fit a starter motor heat shield over the starter body.

Battery

Heat speeds up battery wear. The battery insulation kit fits batteries up to 20cm high and up to 1.0m in circumference. It suits lead acid, AGM and lithium batteries, and the material absorbs and neutralises acid.

Spark plug leads

Where plug leads pass close to the headers, heat cooks the boots and the lead ends. Spark plug boots slide over each boot to protect it.

Bonnet underside

Engine heat rises and bakes the bonnet. Under bonnet insulation comes as 10mm and 12mm foam adhesive pads and a premium compressed felt. It fixes to the bonnet underside between the bracing. Check the bonnet still closes cleanly after fitting.

Floor and transmission tunnel

The exhaust runs along the floor and tunnel and heats the cabin from below. Kool Wrap recommends the 5mm heavy duty heat shield for under-car jobs where the exhaust heats the floor. Where the pipe sits very close, an embossed semi-rigid panel mounted on brackets works better. Read how to fix a hot floor in a 4WD or ute for the full process.

Summary table

Heat shield material FAQs

What is the best heat shield material for a car?

There is no single best. For panels you can stick to, an aluminium foil face over a fibreglass core does the most work for the least bulk, and the 1.5mm silver sheet is the general-purpose pick. Under the car above the exhaust, the 5mm heavy duty sheet with its thicker 0.25mm foil face is the one Kool Wrap recommends. Where there is nothing flat to stick to, use a semi-rigid embossed aluminium panel on brackets.

What is the best heat shield material for an engine bay?

Start at the source. Wrap on the headers and a blanket on the turbo lower the radiant heat everywhere at once, which does more than shielding parts one at a time. Then shield the firewall with a 1.5mm silver sheet, sleeve the wiring and hoses, and put a thin gold sheet on the airbox.

Does aluminium make a good heat shield?

Aluminium makes an excellent reflective face, which is why almost every shield has one. On its own it does very little, because reflecting radiant heat is only half the job. The insulating core behind the foil is what stops conducted heat, and a foil face with no core is not a heat shield.

How thick should a heat shield be?

Thick enough to insulate, thin enough to fit. Use 0.5mm where clearance is tight, 1.5mm as the general-purpose thickness on firewalls and panels, and 4mm or 5mm on floors, tunnels and fuel tanks where you have the room and the heat is worst.

What heat shield material can touch an exhaust pipe?

None of the adhesive sheets. Kool Wrap does not publish a temperature rating for the adhesive, so the sheets stay on the panels near the heat. On the pipe itself, use exhaust heat wrap, or a semi-rigid or DCI pipe shield clamped around it where the pipe measures 2 to 3 inches.

Need help choosing?

Start with the hottest part of your engine bay and work outward. If you want the basics first, read what a car heat shield does and where you need one.

Then browse the heat shield range or call 1300 44 33 34 with your engine, your exhaust setup and where the heat is showing up.