...But if it makes you feel good....
Nice rip Fred.
So, all those racers out there (motorcycles, quads, drag cars, sand rails,
drag boats, snowmobiles, etc.) with heat coatings on top of their pistons
are only using it to "feel good"?
On a side note, I know it sure keeps my chrome motorcycle pipes from
turning brown or blue. Oh, and they have not shown symptoms of failure
after years of use. Read below.
...Don't do it. It will droop off due to gravity having
absolutely no creep strength, and will drop in a heap in a few hours. And
it will rust to dust in a few cycles....
...Mild steel has no capability in this operating
regime.
Why is it then that there are hundreds, no thousands, of experimentals out
there (several at this airport)with steel exhaust systems that have been flying
for years, decades, with no problems or symptoms that you describe?
Gary
----- Original Message -----
Sent: Tuesday, January 17, 2012 8:41
AM
Subject: [LML] Fw: Re: Ceramic exhaust
coatings
"But there hasn't been much posted on the subject of interior heat
coatings for the exhaust system."
Can't hurt, reduces the heat flow to the metal slightly, but only
slightly. Too thin and has too high a thermal conductivity
to help much. But if it makes you feel good. Leave the
outside surface alone and let it turn its natural black. When the
exhaust manifold has reached the end of its life due to thinning of
walls extensive cracking, or creep (see picture posted by Brent),
replace it. Think of exhaust manifolds like oil filters.
Plan on regular replacement depending on the operating regime.
More demanding (such as turboappliction), shorter replacement
interval.
Don't even think about Inconel (very high temp alloy) exhaust
headers. Not worth it.
"I might go with a mild steel system if I were to do it
again."
Don't do it. It will droop off due to gravity having
absolutely no creep strength, and will drop in a heap in a few
hours. And it will rust to dust in a few cycles. That is why
stainless steel is used - because of its higher strength at elevated
temperatures and because of its corrosion resistance under the same
conditions. Mild steel has no capability in this operating
regime.
Fred |