</font><blockquote><font class="small">Quoting G:</font><hr />
I think a good coating would do a better job than this unit.
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I was actually really surprised that after running the numbers, ceramic coating reduces radiative heat transfer about the same, or slightly more than the heat shield in question. I did a simplified check, but it should be about right. One coating company said surface temperature reduction is typically 33%. Since radiative heat transfer rate is based on temperatures raised to the 4th power, I realized cooler surface temps could have a BIG impact on total radiative heat transfer.
Right off the bat you can credit the heat shield with reducing radiative heat transfer by 50%. In reality it is probably more.
Running the numbers with a ceramic coating that provides 30% reduction in surface temperature results in a radiative heat transfer reduction of ~50%. Given an uncoated manifold is 500°F, the coated manifold would transfer half as much heat radiatively. At an uncoated manifold temperature of 1500°F, the transfer rate is reduced by 65%!
So moral of the story is that ceramic coatings are badass. Given things are equal, I think coating would be the clear choice.
The heat shield still probably has certain advantages such as cost, downtime, and keeping air flow off the manifold. But like anything there are pros and cons.
I think after running the numbers the sweet spot is ceramic coating + SS heat shield. <img src="/ubbthreads/images/graemlins/grin.gif" alt="" />