I was just wondering if anyone has insulated their exhaust to cut down the under bonnet temperatures?
If so which material/product did you use? Are ceramic coatings as effective as a cloth/foil wrap?
Having spoken to many people on this subject, there appears to be an awful lot of myths and repeated inaccuracies out there!
The heat generated by exhaust gases will affect the molecular structure of an exhaust system and break the steel down - in around 50 years. Exhaust wrap will accelerate this process, reducing it to 30 years. I think that I can live with that!
A properly constructed exhaust manifold will not crack when coated or wrapped. However, the extra heat kept in the system will find out any weaknesses in cheap, old and/or badly made ones.
For metal to rust two things are needed, oxygen and water, Therefore, exhaust wrap will not, in itself, promote rusting. On the contrary, unless it is constantly very wet, wrap will actually protect the metal from moisture. I suspect that any system that breaks down has another cause other than purely exhaust wrap (see previous paragraph).
By insulating the exhaust system, you keep the gases at a higher temperature for longer. This expands the gases, causing them to flow faster thereby clearing the cylinders more efficiently. On turbo installations this has the added bonus of reducing lag. Reducing underhood temperatures will reduce intake temperatures, further improving performance. It will also make working on the engine safer.
If you wrap an exhaust, you need to do it properly and keep it maintained. However, unless they are next to delicate items (wires, plastic items etc), small holes in the wrap will only result in slightly higher underhood temperatures.
One big disadvantage of using wrap is when trying to insulate intricate and awkward shapes. This is where ceramic coating comes into its own. For example, standard cast iron manifolds are difficult, if not impossible, to wrap efficiently. Ceramic coats, however, can be applied to any surface accessible to the applicator. They are susceptible to impact damage so care must be taken in installation and maintenance.
Another disadvantage of wrap is trying to keep it in place, not an issue with ceramic coatings.
The main advantage of wrap is the cost (much cheaper than ceramic) and DIY (it can also be done on the car).
Ceramic coatings are an advantage in confined spaces as they are very thin when compared to wrap.
Aesthetics is a very personal thing, so it depends on whether you prefer the look of wrap or ceramics.
According to Peter at Zircotec, their plasma-applied coating will reduce exhaust radiant temperatures by between 30-40%, depending on initial temperature. The higher the temperature, the greater the %age reduction.
Claims for temperature reductions using wrap vary (in my research) between 30 – 70%. If you believe this higher figure, then wrap is the winner. However, I don’t.
What I have been unable to find out is whether you use ceramic and wrap together. Zircotec have not done any research on this so couldn’t help. We decided that my best course of action is to go with ceramic coating and plenty of heat shielding to the bulkhead and intake tract. Turbo will be treated with a blanket. If temperatures are still too high, I will experiment with wrap over the ceramics.
As for cost, Zircotec quoted me £225 for my Cosworth 4WD manifold and £45/foot for my 3inch exhaust system.
Any questions? Fire away I and I will do my best to answer them.