All you need to know about exhaust wraps
"Locking in the heat and keeping the engine bay cool"
High engine bay temperatures are one of the biggest, and most often ignored, performance killers.
Ideally you want the engine to have a ready supply of cold air because it carries more oxygen than warm air, and because this allows you to burn more fuel you make more power.
Where does this heat come from? Obviously the engine block gets quite hot but the real issue is actually the exhaust system.
The exhaust gets really hot and it readily gives up it's heat to the engine bay. So one defence is to lag the exhaust which will help prevent the heat escaping within the engine bay.
You have 2 options which you can even combine but let's look at a few myths first.
Myths about exhaust wraps
We all know that as hot metal gets altered at it's molecular level with visible expansion, contracting and even glowing when it gets hot enough. This constant flex of the structure leads many people to assert that exhaust wrap will cause the exhaust to prematurely age.
In reality a modern exhausts metal integrity will last for 20 years until it suffers from corrosion. Flexing and expanding does little to reduce the lifespan, so adding an exhaust wrap does little to reduce the life of an exhaust and may even increase it if it creates an air proof barrier preventing external rust to form.
It is fair to say that in a cheap or badly made exhaust you may get accelerated wear or cracked joints if it gets too hot - but don't blame the wrap for that!
In fact keeping the heat in the exhaust for longer will help to reduce the moisture content and will minimize the internal rusting.
Because you are keeping the exhaust gases hotter you will find they flow better out of the engine. Turbo owners may also experience slightly reduced lag as a result of the faster flowing exhaust gases but turbo's don't like too much heat and need plenty of fresh oil.
So what are the 2 primary exhaust wrap options? 1st there's a thermal bandage type wrap. You simply wrap this around the exhaust.
How to apply thermal bandage type of exhaust wrap
It is important to keep the exhaust wrap tight and overlap the previous layer slightly with each rotation.
Small gaps in the exhaust wrap will not affect the overall efficiency of the wrap so you don't have to be paranoid about coating the whole down pipe - joins, mounts and corners can be tricky.
The thicker the wrap the greater the insulation, so bear this in mind.
Your other option is the bonded ceramic coating. Ceramic is a very poor conductor of heat so is ideal to have on an exhaust where heat will be trapped inside.
A ceramic coating also looks much neater with a powder white/cream finish on the treated surfaces but other colors are available.
How to apply a ceramic exhaust coating.
Ceramic coatings are applied in spray form under extremely high temperatures causing it to chemically bond with the metal exhaust surface.
This is not the same as paint with ceramic particles. These types of high temperature paints are only fractionally effective compared to a proper ceramic coating.
Good preparation is key. If the exhaust surface is poor then you will potentially suffer from peeling and flaking. Most ceramic coatings are applied to brand new exhausts for this reason.
You could apply both for the maximum effect! A ceramic coating and a wrap will dramatically increase the thermal insulation of the exhaust.
How much will the under bonnet temperatures reduce? There are claims of 30-40% for ceramic coatings and up to 60% for exhaust wraps. By combining both methods you could reasonably expect to achieve the 50% mark.
How much of the exhaust should be wrapped? TorqueCars would expect the optimum effect would be to completely wrap the headers and down pipe upto and including the catalyst.
A hot catalyst is more efficient so your catalyst will last longer and work better if you apply a wrap! It can also help dpf filters to stay clean.
There is nothing stopping you from wrapping the entire length of the exhaust but you need to remember that the aim is to reduce the under bonnet temperature.
Other budget options which can be effective include using high temperature paint and silver foil.
You still cant beat something made for the purpose though in terms of cost to benefit.
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