Partofthechaos
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| posted on 9/11/25 at 05:19 PM |
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Exhaust Instalation Question
Hello All, I am about to install my exhausts and I am worried about getting the silencers too close to the side panels. Is there a rule of thumb for
the distance between the silencer / manifold and GRP? I could do with it being as close as possible to make the manifold ergonomics work, otherwise
I'd just move it out a bit. I don't have any guidance in my build manual and I haven't been able to find anything definitive on-line
anywhere. All thoughts welcome.
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adithorp
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| posted on 10/11/25 at 11:41 AM |
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Headers, exhaust or silencer? Silencer doesn't need much gap. Seen plenty at an inch or less (particularly at the back). Headers and pipe want a
bit more as they're always hotter. A couple of inches I'd guess.
"A witty saying proves nothing" Voltaire
http://jpsc.org.uk/forum/
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Partofthechaos
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| posted on 10/11/25 at 02:19 PM |
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Thank you, that ties in with what I had hoped.
Bit of everything really, I need to fix the silencer distance first, but the gap here is amplified where the side pipe meets the manifold. I
don't want this too far from the side panel, but I don't want the silencer too close.
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jacko
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| posted on 10/11/25 at 02:42 PM |
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Exhaust bandage is your friend on the headers it helps keep the heat down and stops you burning your self on them
If you look in my photos archives you may give you some ideas
Graham[pg]90317[/
 
Description
[Edited on 10/11/25 by jacko]
[Edited on 10/11/25 by jacko]
555
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nick205
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| posted on 11/11/25 at 08:32 AM |
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Installed my MK Indy exhaust like this, with no issues
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Partofthechaos
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| posted on 11/11/25 at 09:02 AM |
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Thanks Both, I plan to use heat wrap under the bonnet to keep the engine bay temps down, but I was worried about the proximity on the out side. Both
of yours are closer than I had expected with no issues, so that gives me some confidence! I will have a look at your albums. Thanks!
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nick205
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| posted on 11/11/25 at 10:47 AM |
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quote:
Originally posted by Partofthechaos
Thanks Both, I plan to use heat wrap under the bonnet to keep the engine bay temps down, but I was worried about the proximity on the out side. Both
of yours are closer than I had expected with no issues, so that gives me some confidence! I will have a look at your albums. Thanks!
4 pipes coming over the side got too hot to touch after driving.
Never discoloured the GRP though.
The silencer (right at calf height) got warm, but not scalding hot - just take care when wearing shorts.
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Partofthechaos
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| posted on 11/11/25 at 10:56 AM |
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Good to know.
In my head the manifold would be glowing at 700 degrees, the silencer is hot enough to melt your leg and there are flames out the end trying to cook
the tyre. While I suspected this was OTT I wasn't sure where reality was, your car sounds cold in comparison!
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Sanzomat
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| posted on 11/11/25 at 11:29 AM |
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One thing to add to what others have said - pay some attention to the outlet from the silencer. On mine the outlet had a short 45 degree angled bend
about 80mm from the GRP rear wheel arch. The builder (not me) had assumed the 45 degree bend would be sufficient to direct the hot gasses away but it
had burnt a hole through the arch. I changed it to a full 90 swept bend that came out to very slightly beyond the wheelarch. I covered the hole with a
bit of thin stainless to both deal with the ugly hole and act as a heat deflector and its been fine since. I did manage to burn a hole in the wheel
arch of my trailer running the engine with the car on the trailer though! The gasses exiting the exhaust are hotter than you might think and there are
the odd flashes of flame on the overrun on track days.
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jacko
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| posted on 11/11/25 at 12:41 PM |
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The only thing that bothered me was if a Yong child put there hand on the exhaust when hot
Graham
555
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Partofthechaos
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| posted on 11/11/25 at 12:44 PM |
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quote:
Originally posted by Sanzomat
One thing to add to what others have said - pay some attention to the outlet from the silencer. On mine the outlet had a short 45 degree angled bend
about 80mm from the GRP rear wheel arch. The builder (not me) had assumed the 45 degree bend would be sufficient to direct the hot gasses away but it
had burnt a hole through the arch. I changed it to a full 90 swept bend that came out to very slightly beyond the wheelarch. I covered the hole with a
bit of thin stainless to both deal with the ugly hole and act as a heat deflector and its been fine since. I did manage to burn a hole in the wheel
arch of my trailer running the engine with the car on the trailer though! The gasses exiting the exhaust are hotter than you might think and there are
the odd flashes of flame on the overrun on track days.
That makes sense, I am hoping mine will be OK, but I'll definitely give it some space.
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JAG
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| posted on 11/11/25 at 02:06 PM |
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quote:
only thing that bothered me was if a Young child put there hand on the exhaust when hot
This has been a worry for me too. The manifold, in particular, would leave a horrible burn 
I've seen Silencer shields (to protect people getting in/out I guess??).
Has anyone ever seen a heat shield on the manifold?
Justin
Who is this super hero? Sarge? ...No.
Rosemary, the telephone operator? ...No.
Penry, the mild-mannered janitor? ...Could be!
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jacko
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| posted on 11/11/25 at 02:09 PM |
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Description
This may help you
 
Description
[Edited on 11/11/25 by jacko]
555
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Partofthechaos
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| posted on 11/11/25 at 02:41 PM |
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quote:
Originally posted by JAG
quote:
only thing that bothered me was if a Young child put there hand on the exhaust when hot
This has been a worry for me too. The manifold, in particular, would leave a horrible burn
I've seen Silencer shields (to protect people getting in/out I guess??).
Has anyone ever seen a heat shield on the manifold?
Tin tops have them often enough, not very elegant though for the outside of a car. Our 3 year old knows not to touch the cooker or a car engine due
to heat, so I will do the same with the exhaust when it is finished. Doesn't help randoms in a car park though. Hopefully the mutual respect of
not touching someone else's car will mitigate to an extent.
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Partofthechaos
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| posted on 11/11/25 at 02:42 PM |
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quote:
Originally posted by jacko
Description
This may help you
Description
[Edited on 11/11/25 by jacko]
Thank you, yes that is another manifold and silencer snug to the bodywork. It looks like I am overthinking it a bit.
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nick205
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| posted on 11/11/25 at 04:09 PM |
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Complete exhaust for a better view.
MK supplied.
The end bend was ample to deflect heat and fumes away from the GRP wheel arch.
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coyoteboy
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| posted on 12/11/25 at 12:29 PM |
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Makes me laugh that the IVA doesn't require heat shields. Small kid falling on that has life changing injuries through no fault of their own. I
personally couldn't use that in public without adding shielding, for my own peace of mind. Looks lovely though.
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nick205
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| posted on 12/11/25 at 01:56 PM |
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quote:
Originally posted by coyoteboy
Makes me laugh that the IVA doesn't require heat shields. Small kid falling on that has life changing injuries through no fault of their own. I
personally couldn't use that in public without adding shielding, for my own peace of mind. Looks lovely though.
Fair point.
It was SVA for me (pre IVA). The focus seemed to be on having things adequately secured and avoiding sharp edges.
For example the bonnet catches had to meet pretty strict rules on no sharp edges/exposed rivets etc. You may well have burnt yourself before getting
to the bonnet catch!
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JAG
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| posted on 12/11/25 at 03:48 PM |
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quote:
Makes me laugh that the IVA doesn't require heat shields. Small kid falling on that has life changing injuries through no fault of their own
My car passed SVA in 2005 and the exposed manifold wasn't even part of the test. Although, if it had a sharp edge, I suspect it would have been
noticed 
Caterhams Factory built cars tend to keep most of the manifold inside the bonnet/body but there is still a significant portion of very hot exhaust
before the heatshield on the Cat' or Silencer.
Based on the number of cars without any heatshield on the manifold I can only assume that it's not a problem...
...but the thought of such an accident gives me nightmares
Justin
Who is this super hero? Sarge? ...No.
Rosemary, the telephone operator? ...No.
Penry, the mild-mannered janitor? ...Could be!
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