02GF74
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| posted on 8/6/06 at 09:21 AM |
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max. temp for using silicon sealant?
I want to reduce the temperature of my bonnet above the exhaust manifold.
In true locost fashion, I am thinking of bolting on an thin ali sheet about 15 mm from the bonnet and then filling up the space in between with an
insulator.
The wall cavity foam type stuff would be ideal but it is flammable so thinking of making a matrix of silicone sealant beads to keep air in
"cells" since I have that stuff.
Temperature I reckon should not be more than 120 C - is that ok for silicone sealnt stuff?
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graememk
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| posted on 8/6/06 at 09:41 AM |
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i hope its not flammable as i've packed my silencer with it, i'm also thinking about bonnet and side wall heat as its a prob in my kit
now when you say insulation do you mean that stuff in a can ? it goes everywhere but where you need it.
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joneh
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| posted on 8/6/06 at 09:47 AM |
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Wouldn't the air cells just get hot too? It might be best to get some small metal standoffs and allow the air to flow.
I've seen some sealants safe up to 250C but I guess it depends on what stuff you have?
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02GF74
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| posted on 8/6/06 at 09:56 AM |
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quote:
Originally posted by graememk
i hope its not flammable as i've packed my silencer with it,
now when you say insulation do you mean that stuff in a can ? it goes everywhere but where you need it.
soundss like the same stuff - right bugger to remove too.
the insulation stuff I was refeerring to is the expanding foam type,
similar to this but the cheap stuff from B&Q that is
not fire rated. It states on the can that is should be used away from heat sources.
I wonder if the screwfix fire foam I just found can be used instead, but at £ 7, seems pointless if the silicone stuff works as I have that
already.
[Edited on 8/6/06 by 02GF74]
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UncleFista
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| posted on 8/6/06 at 10:03 AM |
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The last Silicone exhaust paste I saw was rated up to 300c
Tony Bond / UncleFista
Love is like a snowmobile, speeding across the frozen tundra.
Which suddenly flips, pinning you underneath.
At night the ice-weasels come...
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02GF74
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| posted on 8/6/06 at 10:04 AM |
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quote:
Originally posted by joneh
Wouldn't the air cells just get hot too? It might be best to get some small metal standoffs and allow the air to flow.
I've seen some sealants safe up to 250C but I guess it depends on what stuff you have?
hmmm, but is that how quilts and north face daown jackets work by trapping air in the down and air is a good insulator??
did wonder aboutthe air flow as you mention but the problem I suspect will be worse when stationary so little flow.
I guess I'll try a plate to see how it goes, then thnk about sealants, mats etc.
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RazMan
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| posted on 8/6/06 at 10:39 AM |
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How about using some alluminium cloth ? - it's designed for the job. I know it's a bit more expensive but it will be quicker to install
and will perform much better.
Cheers,
Raz
When thinking outside the box doesn't work any more, it's time to build a new box
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02GF74
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| posted on 8/6/06 at 11:21 AM |
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quote:
Originally posted by RazMan
How about using some alluminium cloth ? - it's designed for the job. I know it's a bit more expensive but it will be quicker to install
and will perform much better.
but £ 25 vs free, hmmmmmmmm.......
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NS Dev
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| posted on 8/6/06 at 11:55 AM |
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Bathroom silicone sealer and ally sheet will work just fine, though they may try to part company after a while.
Give them a try though, nothing to lose and the silicone will be fine at that sort of temp.
Retro RWD is the way forward...........automotive fabrication, car restoration, sheetmetal work, engine conversion
retro car restoration and tuning
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graememk
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| posted on 8/6/06 at 12:13 PM |
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what about the fire blanket out of the kitchen ?
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MikeR
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| posted on 8/6/06 at 05:37 PM |
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why not just get some ali sheet, create some thin ali strips and make them into spacers, rivet the lot together so you've got .........
*********thin ali sheet*************
*spacer*__________________*spacer*
*********thin ali sheet*************
no silicone worries now (short or long term) and the same effect.
edited to try and improve the ascii diagram
[Edited on 8/6/06 by MikeR]
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02GF74
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| posted on 9/6/06 at 08:35 AM |
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Mike - that is what I am thinking but without the spacers since metal one would conduct heat.
current thinking is that a sheet about 10 mm away may work.
when driving, there will be air flow so under bonnet temp should be ok.
when stationary and idling, the stationary air "trapped" between the plate and bonnet will act as an insulator.
(I've already have the holes in the bonnet, just need to find the metal sheet)
For the time being, I'm keeping away from echasut wrap due to it trapping moisture and rustingthe manifold and it will be awkward to wrap round
the 2 traingular boxes (4-2-1).
[Edited on 9/6/06 by 02GF74]
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MikeR
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| posted on 9/6/06 at 10:24 PM |
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i'd have thought (ie i'm no expert) that the amount of heat transmitted by a few small (1 inch) spacers would have been minimal
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RazMan
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| posted on 9/6/06 at 10:27 PM |
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Rivnuts as spacers?
Cheers,
Raz
When thinking outside the box doesn't work any more, it's time to build a new box
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