[DML] Re: Asbestos vs stainless steel heatshields

[Diane-jen <diane-jen@xxxx>]

Stainless steel will reflect heat if the surface is polished. With a mat black
finish most heat will be absorbed. A polished surface on the other side of the
stainless steel sheet will give a low coefficient of radiant heat transfer. But
it's unlikely you can keep these surfaces highly polished. If not polished, the
stainless steel sheet or plate will absorb heat on one surface, conduct it to
the other surface, and emit it on the other side It will provide some shielding,
however. It might work just fine.

Asbestos sheet absorbs heat on the hot side, but it has a very low
conductivity. This means that onside could be very hot, and the other would be
much less hot much less hot. The less hot surface, toward the engine, would
give off much less radiant heat than the hotter stainless steel.

In this application there is little danger from the asbestos. However, the
asbestos sheet is more likely to deteriorate over time. Mine looks a little
raggy on one surface, but it's still intact.

I hope this helps, and if you go with the stainless steel I'd be interested in
how it performs.

A thermocouple temperature indicator used on the engine facing side of the
middle of the shield will indicate it's performance versus an asbestos sheet
heat shield, the lower temperature being the best heat shield. Warm up the
engine then let it idle for 15 minutes before taking the temperature.