MG MGB and MGB GT Tech Talk
I posted this in the Motorsport section too but thought I might get some additional advice here.
Jet Hot says it increases horsepower and reduces header temperature. The local powder coating shop says crystals and flaking can be a problem and doesn't recommend it. Should I pay the extra price and go with Jet Hot or is the local shop correct?
Jet-Hot claims to have a type of ceramic coating they apply ?, powder coating is usually done with an electro-static charged paint and heat. the paint is heated to around 500 degrees + - and flows evenly over the surface and cools. the basic J/H ceramic coating is different and will withstand up to 1300 degrees. they also have other coating that go to a higher temp range. J/H did my V8 headers. they are still great after 2 years and 12K miles. usually the ceramic is for headers, etc., powder coating is for suspension, frames, etc. i don't think P/C will successfully take the heat generated in headers. these 2 coating are totally different and have different applications on autos. this is my basic understanding of the processes and by no means complete or technical.
Just My 2 cents worth.
Get the JetHot information packet they send out for free. You'll also notice in their brochure that the average engine loses low-end torque due to increased cylinder temperatures caused by trapped heat that would have previously dissipated through the manifold. If JetHot does your header, they don't give you an option on NOT doing the inside. I believe its required for the durability of the finish! Powdercoating on the other hand, I don't know. Isn't there someone on this board who's tried it?
I would not recommend using powders on headers, I dont believe they would hold up very well.
I used a ceramic bake on coating on mine externally from Pendry.
https://www.pendrypowdercoatings.com/shop/index.php?cPath=44&osCsid=b4441146ed0631ffaacc1111b11ee779
I am considering using this place for an "air dry" coating to do the inside when my motor is closer to being ready to run.
http://www.techlinecoatings.com/Exhaust.htm
Powder coat is not the same as Jet Hot or other ceramic header coating processes. I have an old Yamaha motorcycle with what was called "Black Chrome" pipes. I understand it was a ceramic coating and not too durable at that. I searched high & low looking for someone that could redo them. Jet Hot said they only offer flat black cause the only way to get gloss black is with powdercoat and it won't withstand the heat. As far as the heat retention, I can't imagine a header, even a coated one, retaining as much heat as a cast iron manifold. Most of the silver Jet Hot that I have seen, includeing mine, will lose gloss from the heat turning a sort of gray. They still look better than rust though.
The guy I have been talking to about doing some powder coating was telling me that he has a ceramic coating that is designed to withstand 2k degrees. He tells me that if/when I have my header and manifold coated, he always does inside and out.
He also tells me that the stuff he uses is guaranteed not to flake, etc, etc.
When I drop off my stuff to him, I will ask him if he has any other info on the ceramic coat stuff.
I think part of the problem out there is that people confuse ceramic coating with powdercoating because of company names. Monte's post is a perfect example. Pendry Powdercoating does ceramic coating, hence some poeples' use of the term "powdercoating" as a generalization for all their services. I believe there are powdercoats made from high ceramic content, making them suitable for headers though. Traditional powdercoat would probably last about as long as good header paint.
Jet Hot coating is very durable as noted in my earlier post. i am very pleased with their product and service. i failed to make a complete weld around one tube and had a pin hole, called J/H and advised of my error. they asked me to return the one header and pay only the return S&H. they re-coated the header and returned to me quickly. J/H gets my vote of quality and service! it is difficult trying to imagine a 4 cyl. street engine expelling any more heat than my slightly modified V8. the basic Sterling coating was applied to my headers and still looks great.
Mark,
Powder coating is a ply urethane in powder form which is spray onto a metal surface at room temps and then baked in an oven at 210 C to fuse the coating to the base material.
Ceramic coatings vary depending on the process.
Normally they are in a liquid form at room temps (called a slip by the way) into which the item is dipped.
Some are sprayed at room temps.
They are then baked in an oven to set the slip into a coating.
Since they are ceramic the coating is usually able to handle a higher temperature than the base material the coating can be very thin.
The base material is usually melted in a ceramic crucible at the foundry before being formed into rod , bar , sheet or whatever form it ends up in.
Both depend a lot on the skill of the operator to get an even coating and complete coverage but urethane powder coatings will met at the temps normally experienced by exhaust systems.
There is a lot more to this but the above will I hope provide the basics for your initial question.
Good luck , Pete.
A few words on the long term durability of ceramic coated headers.....
I know that the current "hot-ticket" these days is to coat manifolds and headers.. mostly because it looks cool. What most don't realize is that, if you ever need to do repairs or any welding on coated headers, it is almost impossible.
Case in point, Rover used ceramic coated headers from the factory on the P6 series cars... ie. the Rover TC 2000's. They were a true HP style, what today would be called a *TRI-Y*, a 4 into2 into 1 tubular design. Ceramic coated inside and out.
Fast forward 15-20 years....... those wonderful headers now need repairs... due to corrosion from hot exhaust gasses... vibration damage fom many road miles... ect.....
This damage soed up as cracked welds between tubes... and soft spots where the exhaust gasses had burnt away the interior coating allowing rust to form.
You say no prob...you'll just grab the welder and do a few repairs??? HAAHAA..... ANY welding will allow the ceramic to enter the weld bead.. creating a weld that is as brittle as glass........ The ONLY way to weld onto or repair a ceramic coated header/exhaust is to first grind away ALL the surrounding ceramic coating!! then you are left with clean metal..... another problem pops up.. the metal you are left with is now way too thin to weld to without comprimising the streangth of the tubes.....
I have spent many many hour chasing cracks and or re-welding the headers till I've screamed........
What I ended up doing was to have a custom shop that makes race (NHRA/NASCAR) headers build a jig/buck (to the tune of several hundred dollars) to custom build a NEW set to original specs... the new headers made out of mild steel..... and today?? have out lasted the original "factory" ceramic coated headers........
So remember..... while those ceramic headers may look great new.... you can not repair or modify them... if you want/need to? your only option is to lay out the $$'s and buy a new set!!!
Michael
Maybe but in 15-20 years who know what magic welding solutions may have been discovered?
I understand your post but I really think the benefits will outweigh the disadvantages in the long run.
In 15-20 years time I would be happy to "recycle" the orignial parts and have new headers built.
Cheers , Pete.
Thanks for all the information folks. I checked the local shop again and they indeed use ceramic coating on the headers for all the reasons you guys stated. But they claim coating inside will crystallize and flake off. Jet Hot guarantees their work. I think I'm going to save my $ and go with them.
I jsut went to Jet-Hot's webpage, and it looks like they're having a clearance sale on some stuff. They list a Pacesetter header for an MGB for $116. Probably not a bad deal.
That said, Peter Burgess says that he has found that the ONLY header that's better than the stock (non-ZS) cast iron manifold is the Peco, and it's only very marginally better. You'd only notice the difference on a highly-tuned engine running flat out.....
