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Very good point, also keep in mind that the polishing compounds and their agents used on many of these manifolds usually require a chemical or acid bath to completely remove. Other wise you will never get complete adhesion between the coating and the surface of the metal.

 

Rich = cold combustion temps, but hot exhaust gas temps.
Lean = hot combustion temps, but cold exhaust gas temps.

Don't call someone out for calling someone out unless you know what you're talking about. If you don't believe me go pick up a copy of Internal Combustion Engine Fundamentals by John Heywood.

 

+1

 

Go w/ something meant for a turbo application.

 

Well, that's the first I've ever heard ot that phenomenon. Consider me educated.

 

Yes, indeed, you should never call someone out unless you know what you're talking about.

EGT temperatures FALL OFF fairly evenly on BOTH the rich and lean sides of peak EGT. That's why it is not recommended to use only an EGT for tuning -- you need to know on which side of peak EGT you're going, which requires a wide band O2.

On piston engine aircraft engines, for example, peak HP may be 75 degrees on the rich side of peak EGT, while cruising for fuel efficiency may be on the lean side of EGT.

 

Gotcha. I thought I did know what I was talking about. That makes perfect sense, lean or rich can still cause high EGTs depending on the circumstance. Thanks!

 

yeah when i got my stock manifold jet hotted, the tech recommended the 2000F coat.

 

sounds like you need the 2000F coating as everyone is saying.

On a side topic, did they say sand blasting was ok? Some spray on ceramic mfgrs specifically say to not sand blast as prep, but bead blast instead. Evidentally there are issues with silica sand remains on the surface.

 

Swaintech coating has proven to drop underhood temperatures. It is such a great coating that if they coated both sides of the item it may actually cause the metal to break with the expansion of heat. Furthermore being more than a paint it actually is very thick compared to anything else I have seen. If you are going to the extent to get it coated why mess around.

Also Jet Hot may not be the blame either. Did you run the manifold on your car before it was coated? Sandblasting alone is not enough for the metal to be surface prepped. A couple days of heat cycling is the key. I have seen this before on here and the solution was a proper heat cycling of the manifold to cure the metal.

Running rich = more fuel = cooling of the cylinder temperatures. It may or may not affect EGT's although there is a limit to running rich also. It will NOT solve your problems.

 

In the Jet-Hot marketing materials, they say they use "virgin aluminum oxide" to "blast-strip" the part to be coated. Jet-Hot also says they do not use sand or other low-cost abrasives because it will compromise the final finish. So if Jet-Hot preps the part, I'm wondering why the OP took it upon himself to prep it, too.

I do agree with the OP that Jet-Hot should have given him better guidance as to what coating he needed. The marketing kit Jet-Hot sends out is ridiculous - a video, a glossy, full color brochure screaming about the quality job they provide, magazine reprints, and a sticker. I got all of that for a lousy $36 quoted job on an O2 housing (but of course, after reading this thread, that's going to change to a $136 job). If they were half the company they claim to be in their marketing materials, they'd provide better guidance. Especially since their warranty only covers redoing the job in the original coating, which isn't going to help the OP. If it were me, I'd just pay to have it redone with the correct coating and see if they'll give you some sort of break on the cost.

With all that said, here's a snippet of the extremely verbose email they sent to me in response for a quote: But then, a few paragraphs later, is this:So they do warn you about turbos... sort of. But the message is definitely mixed, and buried in a 10+ paragraph email. I can't blame the OP for getting confused. I had identified my part as a "turbo dump pipe" and Jet-Hot happily provided me a quote for the inadequate coating. It appears they have an opportunity to improve their service by better monitoring what services their customers need. Heck, it's an ethical way to upsell, which should thrill the bean counters.

 

Hmmm......very interesting the things you get to read on the internet!

First, we have tried both HPC and Jet Hot. Both companies service were less than stellar. Both companies were also TOO far away and the shipping/waiting times killed us. The coatings we used, which was their highest temp silver, did not hold up well and we did have some flaking on some parts.

Then we switched to another company close to us, also had very poor luck with them.

For atleast the last 8 months we have been using yet another company. The service is excellent and they offer a 1600F high gloss silver coating. This is the best we have found. The coating has held up extremely well and has even proven to stick pretty damn good on the polished SS 02 housings. All of the coatinngs we have found do eventually rust on the cast manifolds if water sits on them for extended periods. It can be taken off with a mild polish like Mothers aluminum polish. The truth of the matter is 90% of the EVO's I see come through the owners don't care a lot about what the engine bay looks like. I am freak and you can eat off any part of my engine bay!haha

As for the EGT's. A leaner AFR will absolutely make the EGT's climb. Tune a car at 11.5:1 and watch the EGT's and then tune it at 13.2:1 and watch out. I also agree that a rich mixture will make them climb BUT there is usually more going on than it just being rich. Most consider an 11-11.5:1 mixture on gas "rich" but the EGT's stay low there and the cars make really good power and last forever. If you have an over abundance of fuel being dumped into the turbine housing it will also burn in the turbine housing causing the high EGT's that have been mentioned here.

Couple that fuel with detonation and retarded timing numbers and you are definetely going to see some high EGT's when it is rich. This example though is more a matter of the tune being off than a "rich" mixture causing high EGT's.

Hope that makes sense and hope I don't go infront of the EVOm firing squad for giving out some information. DB's.

 

DB that clarifies my high EGT confusion perfectly, thanks.
After the previous rich/high EGT explanations I understand it could pose a problem, but it seemed that something else would have to be off kilter for that to happen such as something running improperly or out of tune, not just rich.

So back to the topic, are there "perfect" quality coatings out there that can handle our EGT's without problem or is it only the bright silver coatings that are in question?

 

Well I am glad I read this today. I was unhappy with the Jet Hot coated Buschur parts some of my friends have because the coating was flaking off. So I was considering another place to go for my coating. But now that they are using a different and better coater I feel a lot more confident I will be happy with the results and the finish in time. I thought their gasket matching/porting on my 10.5 was flawless so I was hoping to stay with Buschur on my manifold as well. Thanks for the info Dave.

 

Worlds of difference between Jet Hot Sterling and Jet Hot 2000 coatings. Not sure why DB tried the sterling, other than for the bling factor? I have Jet Hot 2000 on my down pipe and it's lasted well for 3 years -- no flaking, rust or anything. I think the coating cost about $85. And I've had it off a number of times, dropped it, etc. and it doesn't crack or scratch or anything. I had my manifold, turbine housing and tubular O2 Swain coated early in 06 and it also seems to be holding up well, though it's still pretty new. Swain's prices were reasonable as well -- I think the manifold was about $125 to coat, the other pieces less. You've got to handle the Swain stuff with clean hands/gloves when working on the car though or you'll lose all of the bling factor in a hurry. For those who don't like the white look of Swain, you can hit it with a coat of high temp black paint (VHT or similar).