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Originally Posted by richard sanderson
I agree with all these above comments. My new headers were fitted pretty straightforwardly, and we now have all 32 bolts installed. We did not do anything about coating or heat matting - do we risk cooking something?
Cheers from sunny Spain, Dick
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Rich, here's the thing about ceramic heat barrier coatings. Stainless is a great transmitter of heat, it does so very quickly. The OE system had heat shields which I'm sure worked to keep the heat from building up over time to the point where the insulation on the harness wires gets brittle from that heat. In place of heat shielding, typically you ceramic coat headers to keep that radiated heat down for the sake of the wires' insulation versus cooking that stuff over time.
As a bonus, the ceramic coating keeping the heat inside the exhaust tubing serves to keep the heat energy in the gas stream which helps keep the gas stream velocity high so it leaves the system in a timely manner. If the gas stream cools too quickly it will slow down and I guess back things up a bit...not too sure on that point, but I do know that a hot gas will have more energy than a gas that cools quickly. Stainless just transmits heat too quickly, it has no moderating characteristics like steel or cast iron.
Oh, the ceramic coatings that actually do something like keeping the heat inside the tubing are fairly ugly in appearance but they transmit less heat to the motor compartment. I guess ya can't have everything.
Tom