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bkthomps

Well Known Member
Why is it that you rarely see someone with a ceramic coated exhaust setup? Is there some huge downside to this I'm not aware of? I love the results of doing this on my motorcycle, but it seems to be something people avoid in aviation
 
There are lots of people here that will tell you "don't do it.", including Larry. I have several friends that have had their pipes coated and have had zero problems. So I'd say go for it, and if you have problems, let us know. I will be having mine coated soon.
 
I too have far back in my memory banks somewhere a notice that they are less flexible and crack if coated. Could well be old wives tales.
I have a friend who just had his RV12 pipes and muffler coated, trying to keep some heat out of the cowling.
 
I'll ask the flip-side question--What's the upside and cost? Is this a solution in search of a problem?
 
OK, heat. I get that on a bike where the exhaust can be right next to my leg. What's the tangible benefit on a plane? I'm not trying to be obtuse, I'm really interested in what I would get as a return on the cost?
 
bkthomps said:
heat, you can turn the engine off and grab the exhaust with your hand less than 5 mins later, it's quite incredible
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OK, I can do the same thing with my bare Vetterman exhaust. My thought is that it has more to do with the thin stainless tubing's lack of mass and ability to retain heat than a coating.

John Clark ATP, CFI
FAAST Team Representative
EAA Flight Advisor
RV8 N18U "Sunshine"
KSBA
 
To answer two questions, the cost is about $200 for a complete Rotax exhaust system, that is the Highest quality of the several degrees of coatings. I understand you can grab the exhaust WHEN THE ENGINE IS RUNNING after coating. When you are having vapor lock problems from auto fuel boiling, moving heat out of the engine area gets real important..
We had installed temp probes on this installation prior to the coating, the same probes in the same locations will soon tell us if it worthwhile or not.
 
DonFromTX said:
When you are having vapor lock problems from auto fuel boiling, moving heat out of the engine area gets real important..
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Don't disagree about heat, but I fail to see how coating the exahust will help with hot starts due to vapor lock because the surface area of the pipes is so small compared to the rest of the engine. IOW coating the exhaust will only remove a fraction of the heat radiating off the engine after shut-down.

So what other benefits are worthy of 200 clams? I ask because the OP's question was why was it not used more in aviation.
 
unfamiliar

I think it has more to do with lack of exposure and cost than any reasons not to.

The two exp builders I know, that have run race cars would not have an exhaust that is not coated. Keeping as much heat from radiating inside the cowl to other components is always a good thing.

I have not seen any specific testing on aircraft exhaust. I have seen an article in a hot rod magazine that took temps with the same engine, one with a coateed header and one without. The measured radiant temp was about 300 degrees less coated.

I have a coated exhaust and there are 3 RV's at our airpark that do not have any coating. When I start running my engine I will take readings and compare.
 
Northern climates

If you live up north or fly very high you need the heat from the exhaust to heat the cabin. The muff does not work as well if coated and it can get mighty cold in the cabin.
 
I was not referring to heat after shutdown, I was talking heat while flying, vapor lock can make you hit the "nearest" button on the GPS in a hurry. With liquid cooling on the Rotax, cabin heat is not a factor. As to why it is not more widely used, simple, if you don't have a vapor lock or overheating problem, why bother.
 
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Data needed

DonFromTX said:
As to why it is not more widely used, simple, if you don't have a vapor lock or overheating problem, why bother.
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As Todd asked in Post #4, "Is this a solution in search of a problem?" I really would like to see the results of properly instrumenting the inside of the cowl, without some hard numbers this is all anecdotal.

John Clark ATP, CFI
FAAST Team Representative
EAA Flight Advisor
RV8 N18U "Sunshine"
KSBA
 
It will keep the surface temperatue of the pipes cooler than uncoated, and it will hep keep anything cool that i within about3 to 4 inches away from the pipes. Anything that is more than about 6 inches away will likely not be effected one way or the other. As said, data would be good, but this is what I would expectthe resut to be.

Tim
 
Well, you will see soon enough. We have the instruments installed, and the before coating temps recorded. Stay tuned for the results!

John Clark said:
As Todd asked in Post #4, "Is this a solution in search of a problem?" I really would like to see the results of properly instrumenting the inside of the cowl, without some hard numbers this is all anecdotal.

John Clark ATP, CFI
FAAST Team Representative
EAA Flight Advisor
RV8 N18U "Sunshine"
KSBA
Click to expand...
 
Results

DonFromTX said:
Well, you will see soon enough. We have the instruments installed, and the before coating temps recorded. Stay tuned for the results!
Click to expand...

I just saw this thread and since it has been almost a year I wondered what the data showed. Perhaps it is n another thread but I am very curious as to the benefits of the coated exhaust.

Cheers
 
I did it

When I was building up my engine, I started to research ceramic coatings, since modern technologies use it for many things, especially in the racing industry.
I also read about negatives and then made my decision based on what I believed to be true, since opinions both ways seemed to be biased towards a person's individual or business needs.
I ended up going to Cradin Industries... http://www.cradin.com/ . The owner is a very knowledgeable man about the industry, engines, both air cooled and water cooled, motorcycles, industrial uses and aircraft, since he is also an A&P.
In the end, I had my induction tubes and the exhaust pipes coated. My thoughts on it are:
It looks nice since the coatings can be black, white or chrome colored.
On the induction tubes, the type coating is designed to keep cool in and heat out, so that the air molecules remain cooler, providing more air to the engine fuel mix. (Since hot air molecules expand, the air is less dense, etc., etc. So it sounded good to me.)
On the exhaust, the coating is designed to keep heat in, which keeps the interior of the cowling cooler and gets the heat out the end of the exhaust. Things to note on this include: You can't coat the area where the heat muff is or you won't get much cabin heat. You have to be careful not to attach grounding clips, etc to the exhaust so you don't chip the coating. The Cradin process IS weldable, in the event you need to fix something. Probably want to coat the clamps, too, just to make it look nice.
OK, since the engine was originally built, it had 217 trouble free hours. Then the plane got damaged and the engine rebuilt with a new exhaust. I did not get the new exhaust coated, this time, but I did re-install the coated induction tubes. I don't really notice any difference after about 70 or so hours except the heater doesn't seem to work as well. (Maybe the ceramic coating does keep more heat in the tubes and allows the heat muff to capture more heat.) The cowling did not get scorched due to heat and I do not have the aluminum heat shield material on my current cowling. (I did have to put some on the previous cowl; however, I did paint the interior of my new cowling with aluminum impregnated paint, what we used to call flag pole paint, and it is fine.)
So, not really empirical data, but just some observations I made on my installations.
 
I coated mine

I had my RV-10 coated and have had no issues.
In fact my engine runs cooler than most -10's and all we can think of is the coated exhaust.
As for the heat in the cabin, on the -10 there is plenty. I have never turned the heat on all the way, even when it is very cold.

The one downside I read was if they cracked they can not be repaired as easy.

I have 850 trouble free hours on it.
 
Scott's plane

I have a ten that is not coated. When I fly my ten next to Scott's we compare numbers and the biggest difference is the oil temp. Mine stays up in cruise and Scott's dives back down at least ten degrees below mine. The only difference is the ceramic coating and I believe this makes a big difference with moving hot air out of the oil cooler area.
 
Stras, which airport are you and Scott based at? If I flew over that way to demo for sale, where is easiest in/out? Morgan? OGD?
 
I have mine coated and have had zero issues but it is only about 380+ hours so far, so I am keeping my finger cross.

As for temp goes, my engine runs rather cool, specially the oil temp. As a result, I have installed an oil shutter (I live in CA) and even in 70+ degree weather, I have it partially (50%) closed to get the 185 temp. But I expect in the heat of the summer I will have it fully open.
 
Exhaust coating

I built the first F-1 Rocket to fly back in 2000. My oil temps ran a bit over 200 degrees at cruise on a hot day, so over a period of time I tried everything suggested to get the temps down a bit. One suggestion was the exhaust system ceramic coating, which I did at a cost of several hundred dollars.

That along with almost all other suggestions (such as louvers on the bottom of the cowling) did nothing. I saw no difference when the exhaust were coated both externally and internally, which in my opinion is a complete waste of money. Finally, an additional oil cooler was installed which solved the problem.

Tell you what guys. I have been flying Vans aircraft for 25 years and have owned between 15 and 20 of all types. There is only one thing I am certain of. If you go outside simple, which has always been Van's principle, you are probably making a mistake. Jim Cash
 
I had a Velocity prior to the RV and coated the simple 2 into 1 exhausts both inside and outside.
ran cooler CHTs as the small armpit scoops were drawing air from the bottom up over the exhaust. Had heat bubble on the glass cowl prior to doing it and it eliminated them. EGTs go up about 75 degrees.
On an RV plusses would be:
reduced under cowl temps
longer life on accessories from less heat exposure
cooler fuel/air on intakes (slight power gain)
longer life on fiberglass cowlings
less heat leakage from sides of cowling into naca cabin inlets
downsides:
cost
shorter exhaust lifespan
increased difficulty on reinstallation due to size increase of coating
 
For ceramic exhausts to work well they have to be coated from the inside. And for the ceramic coating to adhere a special wand has to be pushed down the pipes to bead blast the ID of the pipes, and a special spray gun used to spray the coating inside the pipes. Most shops are not set up for doing this so if you decide to have your pipes coated, ask what their process is for the insides of the pipes.
 
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