Exhaust Wrap ?
Discussion
Situation: Rear engined car, Front Rad, Water temp good but engine compartment gets very hot. Particularly the alternator which backs on to one of the exhaust manifolds and Knackers itself every year or two. Initial Idea, Wrap the manifold with thermal wrap, but have been advise by a 'quite knowledgable' friend that this just knocks out the whole exhaust system. He says that it's fine for a track car (where the system is likely to be changed regularly) but not for a regularly used fun wagon. His comment is that the heat has to go somewhere, so It's pushed into the silencer which isn't built to take the extra heat. Have you tried this stuff? or your mates etc? or are you just a clever... who knows these things?
Hi Andy, I did this on my Chimaera - I found it worked well for me (I wrapped the manifolds + about a foot I guess)
As to the fact of pushing the heat down the pipe, yes this is true to some extent, but I think that by the time the gasses hit the silencer, gas temperature difference will be minimal.
Things to think about though: the pipe(s?) immediately after the wrap stops will definately be hotter, so if this runs close to some fibreglass bodywork, then you may need a little heatshield.
Are your manifolds stainless steel? If not, then you may want to use a protective spray coat after you have wrapped them, as the wrap can trap moisture next to the manifold, leading to early cracking.
I did mine a few months after I bought the car & it's been fine for over 3 years now - only issue I've had is that on cold winters days the car takes a while to warm up.
A tip when doing the wrap - if you are wrapping the manifolds in situ, get a plastic coated wire coathanger & bend it into a hook - this makes it far easier to pull the wrap through small spaces...
>> Edited by CraigAlsop on Tuesday 3rd February 15:05
As to the fact of pushing the heat down the pipe, yes this is true to some extent, but I think that by the time the gasses hit the silencer, gas temperature difference will be minimal.
Things to think about though: the pipe(s?) immediately after the wrap stops will definately be hotter, so if this runs close to some fibreglass bodywork, then you may need a little heatshield.
Are your manifolds stainless steel? If not, then you may want to use a protective spray coat after you have wrapped them, as the wrap can trap moisture next to the manifold, leading to early cracking.
I did mine a few months after I bought the car & it's been fine for over 3 years now - only issue I've had is that on cold winters days the car takes a while to warm up.
A tip when doing the wrap - if you are wrapping the manifolds in situ, get a plastic coated wire coathanger & bend it into a hook - this makes it far easier to pull the wrap through small spaces...
>> Edited by CraigAlsop on Tuesday 3rd February 15:05
Thanks chaps.
I'm thinking about the heat shield (as well as the wrap). I guess a double layer of steel with a small gap between them may be the best idea.
Concerning the wrap, Being rear engined the silencer is very close to the manifold. It's has around 6 inches of pipe between the manifold and the box, and even that's curved so the real distance is more like 4 inches. The manifolds aren't stainless, but I seem to remember that there was some form of resin spray available, which you could spray on to the wrapped pipe. I don't know if this seals it from moisture tho. I haven't seen it advertised for a while, It's probably been banned by the EEC!
I'm thinking about the heat shield (as well as the wrap). I guess a double layer of steel with a small gap between them may be the best idea.
Concerning the wrap, Being rear engined the silencer is very close to the manifold. It's has around 6 inches of pipe between the manifold and the box, and even that's curved so the real distance is more like 4 inches. The manifolds aren't stainless, but I seem to remember that there was some form of resin spray available, which you could spray on to the wrapped pipe. I don't know if this seals it from moisture tho. I haven't seen it advertised for a while, It's probably been banned by the EEC!
With only 4 inches between the manifolds & the silencer, I honestly can't see that the silencer will get much hotter than it is already.
What usually kills silencers is corrosion in my experience (usually at the welds for the pipe entrance or exit), & I can't see why an extra bit of heat would make this any worse...
Can you get stainless steel exhausts for Alpines, as these are frequently warrantied for life? Bonus is that it will probably sound better too
What usually kills silencers is corrosion in my experience (usually at the welds for the pipe entrance or exit), & I can't see why an extra bit of heat would make this any worse...
Can you get stainless steel exhausts for Alpines, as these are frequently warrantied for life? Bonus is that it will probably sound better too
Don't forget that heat can radiate in the other direction as well i.e. towards the head which can result in excess heat and warping, especially on aluminium heads.
I think that the heatshield option is the safer one, combined with some venting to the engine cover (louvres maybe?).
Does anyone remember the little Arbath with it's permanently propped open engine cover?
I think that the heatshield option is the safer one, combined with some venting to the engine cover (louvres maybe?).
Does anyone remember the little Arbath with it's permanently propped open engine cover?
boxbush said:You will surely get less heat *radiation* - might get more conduction I guess. Look at it this way however - where's the heat coming from in the first place - the head. The pipes aren't there as a heatsink - which is what is implied by saying wrapping them will result in excess heat & warping. Wrapping the manifolds just stops the heat being radiated from them & pushes the heat down the pipe a bit.
Don't forget that heat can radiate in the other direction as well i.e. towards the head which can result in excess heat and warping, especially on aluminium heads.
Anyway, take all my advice with a pinch of salt, your mileage may vary etc etc. All I can say is I weighed up my risks, did it and am happy with the results.
Thanks guys, It's a 'sports' system on it at the moment, which has a reasonable amount of life left in it. I guess that when it needs replacing I'll go for Stainless and wrapping. Until then I'm leaning towards a heat shield rather than go ceramic (OK finance is also a limiting factor). I looked at agriemach website, who stock the wrap, but they also have a material shield that ties to the pipe and exhaust wrap paint which mentions resins etc. Anyone used either?
Good info on SS
www.burnsstainless.com/TechArticles/Stainless_article/stainless_article.html
With non crossflow engines like B wrap was found to reduce bhp. The benefits of SS is covered in link wheras mild prob needs ceramic coating on both sides, which wrap cannot achieve, SS can be coated just on outside to reduce engine bay temps. There is DIY product called Black Satin from DT.
Paul
www.burnsstainless.com/TechArticles/Stainless_article/stainless_article.html
With non crossflow engines like B wrap was found to reduce bhp. The benefits of SS is covered in link wheras mild prob needs ceramic coating on both sides, which wrap cannot achieve, SS can be coated just on outside to reduce engine bay temps. There is DIY product called Black Satin from DT.
Paul
Alpineandy said:
Thanks chaps.
I'm thinking about the heat shield (as well as the wrap). I guess a double layer of steel with a small gap between them may be the best idea.
Concerning the wrap, Being rear engined the silencer is very close to the manifold. It's has around 6 inches of pipe between the manifold and the box, and even that's curved so the real distance is more like 4 inches. The manifolds aren't stainless, but I seem to remember that there was some form of resin spray available, which you could spray on to the wrapped pipe. I don't know if this seals it from moisture tho. I haven't seen it advertised for a while, It's probably been banned by the EEC!
Demon tweeks sell proper heat shield material - you could always just wrap the alternator in heat shield if you're worried about shagging the exhaust?
I wrapped the headers on my Ultima to reduce engine bay temps...... they are however a grade of stainless that can take it (some can crack) and I did combine this with a free flowing straight through exhaust.
One thing not mentioned is that if your exhaust can get wet it will produce billows of white smoke when started after being left in the rain as the header wrap drys......
One thing not mentioned is that if your exhaust can get wet it will produce billows of white smoke when started after being left in the rain as the header wrap drys......
andycanam said:The white smoke disappeared for me after about a week of use. Steam however is produced on every start in the rain :-)
One thing not mentioned is that if your exhaust can get wet it will produce billows of white smoke when started after being left in the rain as the header wrap drys......
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