adrial

Well, what do you guys think?

The manufacturers of the exhaust wraps say they retain heat better than ceramics, ceramics said nothing about exhaust wraps.

Example:
http://www.designengineering.com/exhaust_wrap_faqs.html

ian

Adrial,

For ease of working with I'm going to side with ceramics, the exhaust wraps seemed to get in the way on the headers and also retained a lot of oil / dirt.

But as far as which is more efficent, I don't have any data to back up anything I would say, and really I would just be guessing.

My last set of headers I used a wrap, the set that will be going into my car in two weeks are going to be ceramic coated, after I see how they hold up I may have the whole crossover pipe done....

How is the project comming along?

adrial

The main downside to ceramics IMO is cost. It's just expensive to coat the crossover and exhaust manifolds.

The project has been in the planning/research stage this past week. The block is completely stripped aside for the crank. I've been calling around to a few mechanics/machine shops and when I return from the Carribean in 9 days (leaving tomorow morning) I will bring the block to 2 mechanics/machine shops to be looked at. After they see it in person, they should be able to give me a pretty good estimate.

I still need to figure out what I'm going to do with the exhaust coatings. But more importantly is that I need to figure out the order in which I will have things done with regard to the coatings and machine work. I imagine I will have everything measured prior to any coatings, and with that information and the knowledge of the thickness of the coatings (I'm thinking piston skirts primarily here) I will know if there is room for the coating or if machine work needs to be done to allow for it. This is of course assuming that the people doing the coating can guarantee to me that it will be that thickness. After the coating, I would probably have the piston to cylinder tolerances measured again just to be sure.

I will likely be sending the crank out to Lindsey for the crossdrilling, unless I find a place that can do it locally.

There's still plenty of work ahead. After the holidays is not a good time to get stuff done, everybody seems to be very busy and not very good at returning my calls!

Mike S

As far as exhaust coatings go....definitely have it done. I wrapped the downpipe on my turbo and had the crossover/header coated in ceramic. Total for those pipes was just over $200. Worth every penny and then some. The wrap is nasty after just a few miles in a non-oily location. The headers look brand new still....except for one that had a ton of oil burned onto it....not sure how to clean that up. Anyways, the heat reduction in coated headers is huge.

As far as the piston coatings....i think i'm going to try it. Right now I'll go with swain tech and use a coating on the top of the piston, on the skirts and on the rod bearings(i'm hoping the rod bearing coating will be especially helpfull).

adrial

Mike, Who did you have coat the crossover and headers for $200?

Mike S

I deleted the bookmark unfortunately, but I can tell you that it was a shop out of sonoma, CA and i think the cost for the downtube and headers was $220-$240 if I remember. I think the quality of the swain tech would be better, but this guy did a really good job and I didn't have any complaints. If I find the link I'll let you know.

turbite

I have a wrapped exhaust manifold.
They've been that way about 10k miles and they look fine. (definately not oily or greasy)
I can safely say I'm glad I saved the money and spent it on something else.
I don't have any data like an EGT, but the wrap seems good.

Mike B

Another option is to 'Do it yourself'...I've ordered the Black Satin but they also have other ceramic paint in chrome, cast iron and aluminium. Columbia Coatings Ceramic Paint

You do need to bead blast the part first but that's it. It should be here in a week or two so I'll post some pics and impressions when I'm done.

ian

My headers are being done by...

http://www.airborncoatings.com/customer/index3.html

if they do a good job i'm taking a spare cross over pipe too them...

turbo944

From what I understand, the biggest benefits are to the life of your pipes between wraps and coating, if coating is done internally AND externally. While you may do better with their wraps and spraying to prevent oil and water from being kept against your headers (coating your wrap!), it does nothing at all for the inside of the pipe, which is where all of the very corrosive and hot gasses pass through. I've heard that even after running for just a few minutes, that this stuff has started to form on the inside of your pipes (at least on mild steel) and that it goes from there, often rotting/rusting from the inside out, not from the outside in. I don't know if the wraps page examined pipes that were coated both in and out or just externally, though, so we can't examine a total truth behind that either. Get the statistics you want and tell the story you want to tell. They may be right, then again, maybe they just tested against external coatings.

My vote would be a good coating internally and externally on those parts.

Alan C.

If you wrap the pipes and drive in an area that uses salt on the roads you will have a problem. The salt will penetrate the wraps and be in close contact with the pipe. That will result in hot salt corrosion which can be very aggressive.

On the other hand the ceramic coating will act as a barrier.

Some of the cheapest mods I have done have been the most expensive ones done first!

Alan C.

Sach951

Any coating that is both internal and external will be more effective than external wraps in one area unquestionably -- turbo spool. Given that the exhaust gases leaving the combustion chamber are expanding extremely rapidly due to the heat generated by combustion, less of that heat and thus exhaust expansion velocity towards the turbo is lost to the piping with an internal coating.

best wishes,
Sach

turbo944

Considering an external coated only and an internal and external coated one, I am not sure how I see the internally coated one would not actually increase rather than decrease it. The coating on the outside means that the heat isn't escaping the pipe and we know the transfer ability of stainless steel. So where would the extra heat go? Would the ceramic not get to its max temp and have to reject the heat back into the exhaust flow of air?

Tony

Ive been looking into this for my 928 pistons going into as SC motor.
Ive found that coating the crown of the piston is really a double edge sword.

On one side it keeps the heat in the combustion chamber..HEAT=ENERGY=HP
and it produce less heat stress on the rings lands..and basically everything below the coating.


The other side is DETONATION. The extra heat retained in the combustion chamber can contribute to detonation.

Im actaully caught in the middle of it all and am not sure what im going to do. The fact that im boosting cast pistons makes me want the extra heat protection for the piston...on the flips side i want the heat outta there!

If i do it, ill go with swaintech though.

Sam Lin

I think it works opposite in regards to detonation, as it keeps piston temps lower than an uncoated piston, and the detonation is more often caused by carbon deposits or another exposed hot spot on the piston - both are reduced greatly by coating.

Sam