Is there really any benefit to ceramic coating the inside of headers? Any thoughts?
If we are talking about SS headers then coating makes very little difference in either header life or engine bay temp. SS just doesn't conduct heat worth a damn so it's effectively an insulator all by itself and it doesn't corrode under most normal conditions either.......so coating them is pretty much purely cosmetic. Coated header will be transfer quite a bit more heat into the engine bay than headers with the factory heat shields or headers with header wrap (not recommended for mild steel headers on street cars but fine with SS). My 550hp 308 with headers that were double wraped where cool enough to touch after a hard run (don't try that with coated headers or you'll find you no longer have skin on your hand). Mild steel headers are another story all together...which is why pretty much all the data you will find on the coating company web sites is for mild steel. Coating these will drop engine bay temp by 10-20F and increase the header life by several times.....getting the mild steel headers in line with bare SS header numbers. Coating the inside of mild steel is an excellent idea.
Are early 308 headers made of stainless? I painted my euro headers with 1500F VHT flat black. It seemed to hold up very well. While the coatings look really good, I fear it would ultimately shorten header life. The euro headers I have are in very good original condition. While I have no way of knowing their exact age, I know they were on that car back in 1982. If they havnt deteriorated in 30 years, and possibly longer, what help could coatings possibly offer?
Steve, I would like to see a picture of this. Also, who did the work (contact info, if possible, please) Thanks, Rob
OK, here are two photos of the exhaust system on my 328. The work was done by HPC Coatings. The parent company of HPC recently bought out Jet-Hot, although they say that the two processes remain different. I live near the facility in Phoenix, and both names are on the door. I have found that HPC does a slightly smoother job, so I ask for that. When I first started using them two decades ago, I asked about temperature drop in the engine compartment. They explained it this way: If you used to be able to get your hand four inches from the header when running, now with HPC coatings inside and out, you can place your hand one inch away. They emphasized that it was the inside coating that made the big difference. I have no reason to doubt them. They did the work over four years ago, and the headers look exactly the same today. HPC has several coatings facilites in the U.S. Their corporate headquarters is in North Carolina, so I assume you could send your parts there. -Steve Image Unavailable, Please Login Image Unavailable, Please Login
Thanks for the header pictures. Can you give the "effective" length of the 4 tubes, and the length of the 2 tubes in the 4-2-1 design? Did you get a boost in mid-range power?
Your guess is as good as mine. All I did was remove the insulation and aluminum covering, which was beat up and ugly, and coat what was under them. -Steve
I can confirm that a properly applied ceramic coat on mild steel headers is bullet-proof. Mike's info. on mild steel vs. stainless [I'm guessing 304 not 409] headers was very useful. I can run my Z full bore for hours and 10 min. after shut off I can put my hand on the header with no problem. Secondly, I have since approx. 1992 logged some 180 K miles on those headers, the headers look every bit as good as when I put them on the engine newly coated. Ciao, George
On my QV the stock setup was 18" and 18" then add about 3.5 to the primary lenght for the port to valve if i recall correctly. I had burns stainless do the design of the headers for my V12. They gave me a 6-2-1 desing with the primaries at 21" (plus 3.5" for the port) x 1 3/4", they asked for the main collector to butt the 2 3-1 collectors making that about 15" and the main collector is a merge type thatr necks down to 2 3/8". They have a software program they put together for all the testing they've done over the year and say that is the ticket for my engine.....we'll see when I get it running
Not to stray from ceramics, but since you brought it up: 1.) Your V12 is from a 400 series, & being installed into your QV, correct? 2.) Do they 'technically' have flat plane cranks? 3.) A 6-2-1 isn't a 180 degree design (which would be 3-2-1), correct? Did you consider it at all? 4.) It seems too convenient that the plumbing would be so straight forward w/these engines (being that the paired cylinders would be 1&6, 7&12, 5&2, 11&8, 3&4, 9&10). I'm sure your space limitations in the QV played a big part in your decision making. Any thoughts?
A 12 cylinder engine, regardless the layout (60 degree V-12, or 180 degree opposed/flat V-12), all use a crankshaft that is basically an inline six cylinder crankshaft with paired rods on the throws. Each bank of a 12 is therefore an inline six cylinder engine and its firing order is identical to an inline six; 153624. The opposing bank follows behind 60 degrees later. Flat cranks are only found in twin cylinder 4 strokes, four cylinder four stroke inline engines, and 8 cylinder V engines. Marks headers then, are a pair of six cylinder headers.
Sorry, by 6-2-1 I meant 6 pipe into 2 collectors into 1 collector. This makes the pairings in groups of 3 and mine are 1,2,3 - 4,5,6 - 7,8,9 - 10,11,12 (ferrari horse shoe number scheme) A 12 cylinder can't be a 180 degree or flat crank, they at 120 degree like a straight 6 which works with the "pairings" in 3s rather than 2s like a 180 degree crank. I guess I could do 2s if I were willing to go bank to bank with the pairs, but then the pipes would be too long and I don't think it would add anything. And to get back on coatings, my headers are 304 SS so I am not plannng to coat them....although the coating sure does look nice......
Sorry to ask again, any idea what oem headers are made of? I assume stainless, would they polish up??
400 series SS. You can polish it but it will oxidize again....coating is a good way to go for a nice clean look.
What do you think of Swain Tech's White Lightning applied to SS? http://www.swaintech.com/store.asp?pid=10969 I couldn't find any data on mild steel vs SS on their site.
Thanks. I might have figured it out if they were in front of me, but they are a ways away at the moment. When you say oxidize, how fast? If it was slow enough it might be worth the effort. Even the high grade stuff needs to be repolished once every so often to keep up its shine. I put VHT 1500 flat black on them when I originally put the car together, and it held up great for almost 2000 miles until I tore the car back down. I couldnt imagine how much work it would be to polish a set of headers. At the end of the day though, black is likely the most appropriate exhaust system color for these cars. VHT makes a 2000 degree F paint that needs to cured, but it only comes in flat colors.
Sorry for the confusion, I was referring to a 180 degree header configuration, & the pairing of the cylinders that are firing 180 degress from ea. other are conveniently on the same bank (as opposed to the nightmares of cross-over pipes over or under the engine that are found on American V8's). I was wondering if you considered this for scavenging / pulsing advantages or if space was at a premium?
A 6-2-1 Header wth the classical inline 6 crank shaft has natural 240 degrees between each exhaust interval when paired up 1-2-3 in one secondary and then 4-5-6 in the other secondary. Not only does this make for perfect exhaust intervals, it also makes for easy tube routing. The V12 And the flat 12 both have this property, but so does the horizontally opposed 12. And if anyone cares, so does the horizontally opposed flat 6 (Porsche) 3-1 headers.
