Exhaust: Heat wrapping - worth doing ?

[RobPhoboS]

I'm curious if I should heat wrap my exhaust all the way to the rear box ?
I believe there are arguments for, and against.

Just wondering what the general consensus is.

[steve y]

I have spoken to several engine specialists and I have been told that while the wrap will lower the under bonnet temperatures the heat inside the wrap will accelerate corrosion and failure of the pipes so it is a trade off of how badly you need to loe the heat and how often you want to replace exhaust

[eccles]

I don't know about accelerating corrosion, but in my experience it tends to make the manifold more brittle and prone to cracking.
Really brings the temp down though.

[RobPhoboS]

yeah, thats pretty much what I thought as well.
Guess it's best to leave it !

[Simon Mason]

If you need to drop temperatures caused by an exhaust there is only one solution. Ceramic coating.

We had our exhaust done by Zircotec for the Britcar 24hrs last year and it was so much cooler within minutes of being off track you could touch the exhaust manifold for longer than you could the cylinder head. It stopped our fuel tank heating up and allowed us to get an extra 12 liters in during the race than ever before.

Its not cheap to do mind, but if theres a genuine purpose to getting temperatures down in your application its the only option in my book.

[ginettajoe]

Simon Mason said:

If you need to drop temperatures caused by an exhaust there is only one solution. Ceramic coating.

We had our exhaust done by Zircotec for the Britcar 24hrs last year and it was so much cooler within minutes of being off track you could touch the exhaust manifold for longer than you could the cylinder head. It stopped our fuel tank heating up and allowed us to get an extra 12 liters in during the race than ever before.

Its not cheap to do mind, but if theres a genuine purpose to getting temperatures down in your application its the only option in my book.

litres, not liters except in America!!

[Nick M]

Simon Mason said:

If you need to drop temperatures caused by an exhaust there is only one solution. Ceramic coating.

We had our exhaust done by Zircotec for the Britcar 24hrs last year and it was so much cooler within minutes of being off track you could touch the exhaust manifold for longer than you could the cylinder head. It stopped our fuel tank heating up and allowed us to get an extra 12 liters in during the race than ever before.

Its not cheap to do mind, but if theres a genuine purpose to getting temperatures down in your application its the only option in my book.

Definitely agree.

If it's a new exhaust manifold then you can also coat the inside as well.

[deviant]

eccles said:

I don't know about accelerating corrosion, but in my experience it tends to make the manifold more brittle and prone to cracking.
Really brings the temp down though.

I heard the corrosion thing comes from the wrap getting damp and holding moisture in it.

[Graham]

Heat wrap can also soak up spilt oil and brake fluid, which makes a nice fire !!!

I now leave my headers unwrapped or ceramic coated..

[dirty boy]

Also, if the wrap becomes 'open' at any point, you'll have a massive hot spot where the heat WILL escape, and could cause massive problems if it's near anything sensitive to heat (fibreglass bodywork for instance)

[rev-erend]

Not recommented for mild steel exhausts.. they really will turn to rust in no time..

[GreenV8S]

It makes the exhausts run hotter which encourages cracks and corrosion. Sometimes the corrosion is blamed on the wrap trapping and holding moisture but personally I find that unlikely unless you have something literally dripping water directly onto the exhaust. The only water your exhaust is going to see is condensation directly on the exhaust (which is very unlikely imo) and any moisture would boil off within seconds of starting the engine. I don't think that water absorption is the problem.

The wrap goes brittle and is quite fragile, you can get a spray-on coating that seals it to prevent fluids soaking in and allegedly makes it slightly less fragile. It's still going to fall apart quickly if you touch it with anything and fall apart slowly due to heat and vibration anyway. You can extend the life by tying it down every few inches with stainless lockwire so that the whole lot doesn't fall off in one lump, but it will eventually all fall off anyway.

[Nick_F]

Wrap has made a huge difference to under-bonnet temperature on the Scimitar - and consequently to intake temperature and to the lifespan of a number of vulnerable bits.

It needs re-doing every two seasons at best, and even with a silicon sealing spray it still sheds fibres all over the shop.

The manifolds are stainless so I can't comment on corrosion.

Worth it on a saloon with a lot of pipe under the bonnet, but ceramic is a lot tidier.

[custardtart]

Main problem is that the heat has to go somewhere, if you wrap up to the manifold then you will just end up with a hotter cylinder head!

[GreenV8S]

custardtart said:

Main problem is that the heat has to go somewhere, if you wrap up to the manifold then you will just end up with a hotter cylinder head!

The gas which is heating up the manifold has already come through the exhaust ports so I think the heads are probably not going to care much if the manifolds get a bit hotter.

[456lbft]

Nick M said:

Simon Mason said:

If you need to drop temperatures caused by an exhaust there is only one solution. Ceramic coating.

We had our exhaust done by Zircotec for the Britcar 24hrs last year and it was so much cooler within minutes of being off track you could touch the exhaust manifold for longer than you could the cylinder head. It stopped our fuel tank heating up and allowed us to get an extra 12 liters in during the race than ever before.

Its not cheap to do mind, but if theres a genuine purpose to getting temperatures down in your application its the only option in my book.

Definitely agree.

If it's a new exhaust manifold then you can also coat the inside as well.

Be careful ceramic coating the inside of turbo manifolds, any loose bits of ceramic will make a nice mess of your turbine wheel. Even on N/A engines particles can back flow through the head, which doesn't help the valve seats. It sounds crazy but it can happen.
I agree with everything else said, don't wrap mild steel tubular manifolds they will fail very quickly. Zircotec is all we recommend that our customers use. The only downside is if you want to weld it once it is coated, and you can't grind it away because it is so hard, and even if you do it seems to bond with the metal underneath and any weld you do will not be very strong or pretty.

[Corpulent Tosser]

deviant said:

eccles said:

I don't know about accelerating corrosion, but in my experience it tends to make the manifold more brittle and prone to cracking.
Really brings the temp down though.

I heard the corrosion thing comes from the wrap getting damp and holding moisture in it.

That is probably hydrogen embrittlement, the wrap gets damp, then the heat evaporates the water releasing the hydrogen, which can diffuse into the metal at high temperatures.

[custardtart]

GreenV8S said:

custardtart said:

Main problem is that the heat has to go somewhere, if you wrap up to the manifold then you will just end up with a hotter cylinder head!

The gas which is heating up the manifold has already come through the exhaust ports so I think the heads are probably not going to care much if the manifolds get a bit hotter.

Goolge is your friend to find there's lots of evidence that supports an increase in engine block temperature associated with use of exhaust wrap.

[GreenV8S]

custardtart said:

GreenV8S said:

custardtart said:

Main problem is that the heat has to go somewhere, if you wrap up to the manifold then you will just end up with a hotter cylinder head!

The gas which is heating up the manifold has already come through the exhaust ports so I think the heads are probably not going to care much if the manifolds get a bit hotter.

Goolge is your friend to find there's lots of evidence that supports an increase in engine block temperature associated with use of exhaust wrap.

You're telling me there's evidence of a problem but not telling me what the evidence is? So, I Googled and clicked on the first few links and there wasn't a single reference to problems due to raised engine temperatures caused by exhaust wrap. Conclusive proof that there isn't any problem.

[flemke]

GreenV8S said:

custardtart said:

GreenV8S said:

custardtart said:

Main problem is that the heat has to go somewhere, if you wrap up to the manifold then you will just end up with a hotter cylinder head!

The gas which is heating up the manifold has already come through the exhaust ports so I think the heads are probably not going to care much if the manifolds get a bit hotter.

Goolge is your friend to find there's lots of evidence that supports an increase in engine block temperature associated with use of exhaust wrap.

You're telling me there's evidence of a problem but not telling me what the evidence is? So, I Googled and clicked on the first few links and there wasn't a single reference to problems due to raised engine temperatures caused by exhaust wrap. Conclusive proof that there isn't any problem.

You may want to read this:

http://www.guy-croft.com/viewtopic.php?f=13&t=...