[MENTION=26435]Old Guy[/MENTION] Thank you for this. I learned something today!
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Hot trunk problem solved
- Thread starter Malibu Rapper
- Start date
That link no longer appears to be valid.
Wrapping the muffler with an insulation blanket that reduces transmission of heat through conduction should work. I can't tell what the wrap is on that muffler. It almost looks more like perforated metal which is going to do very little in terms of reducing heat transmission. What you would want is something like header wrap. The problem with header wrap and similar woven high temperature thermal blanket materials is that on a muffler under the car they are eventually going to become a wonderful dirt and moisture trap. When used on headers the insulation is generally less exposed to stuff and if it does get wet gets cooked off pretty quick. The NSX has a short exhaust system and runs hotter than most (hence the hot trunk); but, I am still thinking that a woven wrap type material is going to eventually be a problem, perhaps providing some interesting odours as it warms up after you drive over that dead squirrel on the road.
The metal heat shield with an air gap on both sides of the shield is a very effective block to the transmission of radiant energy. If you want a simple example of this, find somebody with an late 60s V8 muscle car with exposed headers. There is usually lots or room to the inner fender to carry out this simple test. With the engine idling, hold your hand 4" or so from the headers. Gets pretty hot. Then get a thin sheet of anything non combustible and place it equidistant between your hand and the header. You should notice a huge drop in the perception of heat because of the block in transmission of radiant energy.
If you have an aftermarket exhaust system with no heat shield, fabricating a heat shield just like the one on the OEM muffler (with its all important 1/4" air gap between the muffler skin and the inside of the shield ) would probably provide the biggest improvement in terms of heat reduction versus material added. Unfortunately, fabricating a heat shield that does not look like a grade 9 shop project or rattle like crazy is likely to be a challenge.
On a related note, my recollection (its been 40 years since 2nd year physics!) is that the emissivity of a polished surface is lower than an unpolished surface. A lower emissivity coefficient reduces the radiated heat. So, all of you with the polished SS mufflers, get under the car and clean and polish that muffler for some reduced heat transfer to the trunk.
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Mine is pretty polished at the moment 
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Odd - keeps coming up 'Sorry, no results were found'.
Sent from my iPhone using Tapatalk Pro
Mine is pretty polished at the moment
Sent from my iPhone using Tapatalk Pro
It looks like you have an underbody tray / diffuser. If its is part of an underbody aerodynamics scheme it would be doing its thing correctly if it were stream lining air flow away from the trunk floor and muffler area. Unfortunately, that air flow also provides heat removal so I expect your trunk gets toasty warm. Definitely don't bring your ice cream home from the store in your trunk.
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That looks like it has a foil coating. Is the foil removed to expose the adhesive or is the foil a permanent part of the insulation? If the foil is a permanent part of the insulation, it is designed to be a radiant barrier. The radiant barrier must face the hot source and must not be in surface contact with anything, otherwise its effectiveness as a radiant barrier becomes 0. If the foil is removed to expose the adhesive, then it is an insulator designed to block conduction. It looks awfully thin to provide very much conductive insulation value. If it is like that sticky foam wrap used for piping, it would be pretty minimal.
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Yeah I was thinking that as I looked at it too. Get on my back and get to sticking, or just not worry about it. I vote for option 2.
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