Anyone done an exhaust wrap?

obi_waynne

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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?
 
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?

As it happens, I am in the middle of reseaching this very issue. I will let you know the outcome in due course.
 
I'd appreciate the feedback on this I'm hearing a lot of conflicting reports at the moment!
 
I'd appreciate the feedback on this I'm hearing a lot of conflicting reports at the moment!

Yeah, not easy to spearate the wheat from the chaff.

My Robin Hood has a 4 branch and the wrap had disintegrated so that my feet roasted. Replaced it with standard 1 inch rap from my local spares shop and it made a very big difference. So for normal use, wrap is fine.

However, for the Elan it is a different story. Here, we are talking 950 deg C in a plastic car! I am looking into various methods for getting this down to a manageable level. I will let you know what I find out.
 
Sounds like you'll need and exhaust intercooler to stop the car melting. Interestingly a wrap on the manifold will effectively push the heat through the rest of the exhaust. Why not do a side exit exhaust from the engine bay?
 
The turbo gets so hot it will not really make much of a difference to it. It would stay hot for longer though! My car has a heat shield across the exhaust/turbo made from a silver covered material so I guess Audi aren't worried about this.
 
Hi Wayne, I used to wrap the 4 branch on my MK1 escort race car to keep down under bonnet temp, it worked well, but did have its down sides. The extra temp retained inside the manifold caused the manifold to crack and also on one manifold on a season of endurance races actually caused the manifold to go very scaley and rust through prematurely. I decided to not wrap the replacement manifold, and although the power was down by 3 bhp, the manifold still is in good condition after 3 seasons.
 
Thats interesting Dimma. I am a firm believer that all mods have a hidden cost and it looks like you just found it. Would a ceramic coating work better? What about if the manifold were stainless steel?
 
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.
 
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Wow - a very very comprehensive post.

So Zircotec are offering a Ceramic coating then, what is "plasma applied"?
 
Wow - a very very comprehensive post.

So Zircotec are offering a Ceramic coating then, what is "plasma applied"?

Lifted form Zircotec website:

With plasma-spray process temperatures approaching 10,000oC (18,000oF) the ceramic coating material is melted within our process and propelled towards the component being coated. There, the molten ceramic droplets flatten, cool and then solidify to weld themselves in place. Zircotec's exhaust coatings are therefore extremely well adhered to the underlying component, providing an extremely hard, lightweight yet durable ceramic coating that is highly resistant to vibration, mechanical damage and thermal shock, and protects the underlying component from corrosion.
 
If it is dead smooth I wonder if they could coat the piston walls/piston for a super smooth durable high lubricity finish?

How long are the coatings guaranteed for then? Take some pics I think this is article worthy for the main site. ;)
 
If it is dead smooth I wonder if they could coat the piston walls/piston for a super smooth durable high lubricity finish?

How long are the coatings guaranteed for then? Take some pics I think this is article worthy for the main site. ;)

Coating cylinder walls would not be a good idea as this would restrict heat transference to the coolant system :)

I will ask about coating pistons (maybe crowns) and warranty periods.
 
I was reading up on theory of ceramics in engines some time ago.

from memory said:
If you could build an engine from ceramic you would not need oil to lubricate the parts and you could work to much higher tolerances thus creating a very efficient engine.

Pistons would not change shape nor indeed need to so you get better performance from cold.

The ceramic cylinder walls will prevent the combustion heat from escaping into the engine and your internal friction will be practially nothing as ceramic is so smooth.

Anyway that is how it went although it was more about making a ceramic block and the problem was machining ceramic as this it really hard to do. I just thought that coating the cylinder walls might do a similar job.
 

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