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Old 05-26-2013, 10:32 PM   #1
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Default Exhaust Manifold - HPC coating or not..?

Hi Guys

My little road/race car has just developed a crack in the manifold. I tcame off a race car that had done 4+ seasons of racing so i'm not too concerned it is an ongoing problem.

BUT while it is off, is it worth getting it HPC coated for performance and/or reduce heat and thus potential cracking issues....?

Some friends are saying it is worth doing and others don't.

At $250 - $350 it is a lot to spend on something that may not have an appreciable advantage.....
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Old 05-27-2013, 05:37 PM   #2
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Interesting mx5-kiwi. It sounds like your manifold was pretty durable without coating up to now. What does your manifold look like? Any pics?
If I understand, ceramic coating will cut down radiated heat and surface corrosion but not necessarily increase crack resistance. It probably makes more sense for long runner designs as opposed to logs? (Particularly if it costs 300$)

Also I am curious how much life can be left in a manifold that cracks after 4 years of track abuse. The metal may become fatigued to a point where repairs become less effective?
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Old 05-27-2013, 05:46 PM   #3
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I'll see if i can get a pciture up. The race guys round here seem to think it is a good design.

I realise the ceramic coating itself isn't going to make it stronger but wondered if by being ceramic coated and (in theory) absorbing less heat will then be less likely to crack?

And will it improve performance by retaining more heat in the exhaust gas itself....which is the big theory behind ceramic coating or at least the sales pitch from the company that does it down here....
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Old 05-28-2013, 11:16 AM   #4
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You cant do true ceramic on the inside of the runners so it wont help it absorb less heat. And when you do it on the outside it'll have it throw off less heat so the metal in the manifold will end up hotter. With the ceramic coating and the DEI Ti wrap you can brush against my manifold by accident with your hand and not get burned instantly.
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Old 05-29-2013, 07:27 PM   #5
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So Jonathan, I am curious, do you think the manifold will be more or less prone to cracking by being kept hotter by the coating? Are temperature gradients more damaging than high temperature fatigue? What are the next powerball numbers?
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Old 05-29-2013, 08:17 PM   #6
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You have powerball in slovakia?
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Old 05-30-2013, 02:19 AM   #7
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Forgive my ignorance, but why cant you coat the internals of the manifold...

I always presumed it was a dip type process?

i.e along the lines of electroplating......
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Old 05-30-2013, 08:21 AM   #8
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The material is sprayed on at a very high temerature, if its the real stuff. Proper surface prep requires that you media blast the surface at almost a 90* angle to the surface. Cant fit the media blaster tip in the runners, if they sprayed the coating in there it would just flake off and take out the turbine wheel. The paint requires similar prep.
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Old 05-30-2013, 09:05 AM   #9
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I've cracked cast manifolds with and without ceramic coating on the outside.
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Old 05-30-2013, 10:13 AM   #10
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I'm with Leafy, coating it is just like a turbo blanket or exhaust wrap, it keeps a little heat out of the engine bay, dissipating it instead further down the exhaust system where there is no coating/wrapping/blanket. So I'd think it would technically get hotter.

I think the bigger issue is bracing. If your manifold isn't braced, it's then got the entire weight of the turbo, down pipe, and most of the exhaust hanging off of it. And don't just think a new one will last another 4+ years, it could simply be because you've gained enough skill to go fast enough to use more curb and you'll start going through manifolds every year with those vibrations.

I'd strongly STRONGLY suggest you brace the downpipe with a very wide clamp somewhere between the tranny/block flange and the end of the downpipe first, then look at ceramic coating if you want to get a little ambient heat out of the engine bay.
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Old 05-30-2013, 11:07 AM   #11
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Nitroplate in Nashville, TN uses a waterborne aluminum oxide based coating that will stick to the insides of the manifold. I have it on the header on my street car, and it rocks face. After 30k miles you can pull the collector off right now, wipe the carbon off the inside with a rag and see pretty, intact coating.
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Old 05-30-2013, 05:38 PM   #12
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Quote:
Originally Posted by vehicular View Post
Nitroplate in Nashville, TN uses a waterborne aluminum oxide based coating that will stick to the insides of the manifold.
Will they pay to replace my $1800 turbo if their coating flakes off and destroys it?
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Old 05-31-2013, 12:16 AM   #13
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Thanks guys. That helps clear that up. I'll just save the money.

The down pipe is braced to a bracket off one off the bell housing to block bolts.

Manifold is a shorty type made of steam pipe but the turbo and associated parts sure are heavy hanging on there.....

Incidentally, my last race the car wasn't going as well as it should/could. It was my first race day so I was picking up time due to more aggression and practice in traffic....

I had a hairline crack about 1.5 inches long at the base of the mani/turbo.

Can I blame my getting stuck behind a car I should have been easily around on that do you think...?

I guess my question is, is it conceivable that despite seeing a normal max boost (in this case 7lbs) my engine performance was reduced...?

The crack was only discovered a week or so ago, I had been depressed about not passing a car in the race that on paper I should have not even been bothered by....

I know it's a "how long is a peice of string" question but you guys have some experience with this and may be able to offer thoughts, whereas I don't.
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Old 05-31-2013, 04:03 AM   #14
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At the track I had turbo studs coming lose and was still hitting gate boost, but it took longer to get there and it felt like power was reduced, plus it sounded like my car had an unmuffled wastegate outlet. That's just a "butt dyno" opinion though.
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Old 06-01-2013, 12:01 AM   #15
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Thanks timk, in hindsight that is pretty much what i think I had.
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