Spoke to these ppl
http://skydynamics.com/ as they are just a few minutes from my house.
The guy that owns it does custom 321SS exhaust systems for racing aircraft and restoration. Geeez, talk about having some cool looking eng/stuff around..
Anyway, he took me for a tour and we talked exhausts for close to three hours. This was one of the nicest fellows Ive had the pleasure to deal with. He is a walking encyclopedia of info. He was an engineer at NASA for several years but when I asked him what he was doing in "podunk, VA" he responded... "I was tired of driving a desk, I LIKE to work on aircraft, I LIKE being my own boss...".
Guy just knows WAY more about pipe/air flow/stainless steel/etc than I thought was humanly poss. Hell, Id like to work for him for free just to know what he's forgotten.
Anyway, I asked him about the exhaust coatings and header wrap. He said they were a good "IDEA" but there was one flaw. The coating/wrap does exactly what it says but it fatigues the base metal by "trapping" the heat in for a longer period of time. Which in turn breaks down the metal faster.
(dont quote me on the following numbers as Im going by memory)
If 304SS (what most auto headers/exhaust are made of. His aircraft stuff is 321SS) starts to break down at say 1500deg then wrap/coating will keep the OUTER surface temp down BUT the core of the metal will exceed that. The high temp is not a big deal if it happens and is allowed to cool back down rapidly. That doesnt happen with the wrap/coating. The heat is held in longer and breaks the metal down even faster. Thats why an unwrapped header will be rusty but on average last longer than a wrapped one.
He said the ceramic coatings are way better than the wrap but still do the same thing. It only takes longer to happen.
Before anyone gets their panties in a wad understand that this guy deals in AIRCRAFT exhaust NOT automotive. His theories/thoughts apply to what he's learned in that field. Automotive exhaust is operated at a much lower temp than air craft so Im sure some/all of what he said would be considered overkill for us landlubbers.
Before anyone asks I inquired about a 321SS system (3inch/mandrel bent) for myclone.
".....about $25,000....."
After I picked myself up off the floor I promptly thanked him for his time but explained that was just a little steep for me... (well, he did let me rummage through his "scrap pile" and GAVE me a buncha pieces)
The reason for the price is he doesnt do "onesies and twosies". He is a "manufacturing" facility that does runs in hundreds or for the US Gov/NASA that can pay "$25K" for "one piece"..
Lotsa good info on his site though... Ive put it up before but figured I do it again as someone may enjoy the info on there or even need something.
<font size=-1>[ This Message was edited by: myclone on 2002-02-07 09:48 ]</font>
