Heat insulating fabric help

[Archea47]

Hi Guys,

I am looking to construct a heatshield for my carburators to keep the heat away from the headers. I would like to make it out of a fabric, be it carbon fibre, kevlar, fibreglass etc.

I would like to know what would be the best material for heat insulation? I want to keep the heat where it is -- hot air at the headers and not near my carbs. Also what kind of epoxy should I use? I do not have experience in laying fabric, where can I buy these fabrics and epoxy's also?

Thank you very much for your help!

[marshmat]

I take it you're talking about temperatures that will stay below 200 degrees Celsius? Regardless of the fibre you use, it is the thermal properties of the epoxy that will be the determining factor. (Although I would not recommend Kevlar or any other polymer for extreme high temperatures.)
Most composite heat shields I've seen are made of prepreg carbon fibre, even on Formula1 race cars. However, it requires an oven and vacuum pump to use. A good epoxy like Hysol or WestSystem can be used to wet-lay carbon fibre cloth, probably the easiest solution for you.
You will need to make a mold (out of hard foam, renshape or something similar) in the shape you want your heatshield to take. For a part this small this is not a hard task.
Look in your yellowpages for fibreglass dealers and composite materials manufacturers to find sources of the stuff you need.

[Archea47]

OK cool I can source carbon fibre fabrics. I don't expect to see temperatures in excess of 200C, no.

I wasn't sure if carbon fibre was a heat insulator or conductor

[yokebutt]

Archea, For high-temp service, there is no substitute for mineral-derived materials, but in order to make it look purdy, you'll have to encase it in something, I'd think sheet-aluminium would be a good choice, it's one of the best heat-conductors available.

Yokebutt.

[Archea47]

I would think I need a heat insulator, not conductor?

[FAST FRED]

Locate a place that builds exhaust wrap for inboard diesels & diesel gensets.

They can build exactally what you need , over a simple screen to keep from colapsing.

FAST FRED

[Archea47]

The whole point is I want to make it myself though

[yokebutt]

Archea,
I did a bit of poking around the internet, a company called Cotronics has an epoxy that will tolerate up to 600F. (just google them) It does require a post-cure, but as long as your part fits in the oven, and your wife isn't around to see it, that shouldn't be a problem. Kevlar might just have sufficient heat resistance, if the part is small enough you can just make one and see, if not, just make it out of glass. (glass is mineral-derived and very heat resistant)

To learn to laminate, look around the internet for basic technique, buy some cheap glass and resin, a few mixing cups and a hard-roller, then practice, it's not rocket-science. (google west system to start with)

Of course, if you want to do it the cool way, you'd reverse the flow through the cylinder-heads, put an 8-1 exhaust manifold in the valley, and four Weber 55 DCO side-drafts (like a real engine) on the outside........might be a tad expensive, but it would solve your heat issue.

My thought with recommending aluminium was along the lines of making heat-shields for the exhaust manifold to catch the radiant heat.

Yokebutt.