Timing - again, ceramic

[Dirk Wright]

On Sun, 15 Sep 1996 jac at wave.sheridan.wy.us wrote:

> RE: ceramic surfaces
> 
> The ceramic coating keeps more of the heat in the gasses 
> through the expansion cycle and more energy is extracted 
> from it.

Yeah, ceramics are a good way to keep the exhaust gases hot and the heads 
and pistons cool. In a book I have called "Air Cooled Motor Engines", the 
author talks about how they tried installing a stainless steel shield in 
the exhaust port to help keep the heads cooler. But, since the exhaust 
gas was now hotter, the exhaust valve ran hotter, too. This can be a real 
problem in air cooled engines. We can expand on this idea and note that 
any technique (including ThermoTec header wrap tape and Jet Hot Coating) 
that "keeps the heat in the pipe" will make the exhaust valves run 
hotter, thus shortening thier life. A solution for this is to get the 
exhaust valves Jet Hot Coated also, and/or use sodium-cooled exhaust 
valves. 

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Dirk Wright 					            wright at uspto.gov
"I speak for myself and not my employer."               1974 Porsche 914 2.0
"A real hifi glows in the dark and has horns."            1965 Goodman House
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