trappriverpc

Iv'e been flying for about 8 years now and building kit rc planes just as long and this has never crossed my mind until last week when I experienced my first crash. I picked up what was left of my first build and first fliying plane, an LT-40. I was salvaging peices and parts when I looked at the engine and muffler and thought about what I would use them on next. (I am putting it on a lonestar 50 now) I was cleaning up the muffler and wondered if anyone has ever ceramic coated a rc engine muffler? The reason I thought of it is because it's what I do for a living. Custom Powder coating and Ceramic coating. I wonder if todays rc exhaust would benefit from ceramic coating. Thats my question here, does anyone have any input on ceramic coating an exuast on rc applications? I know the benefits of ceramic but i've only used it on full sized aircraft, cars, tractors, motorcycles, and snowmobile exhaust systems. I am going to coat my little muffler on my OS .46 this coming week for fun. The ceramic I use has a 40% radiant heat reduction. This ceramic in return reduces back pressure, prevents rust and discoloration. Please let me know what you think or if any of you have had experience with this before.

Thanks,
Rich

spaceworm

"...The ceramic I use has a 40% radiant heat reduction. This ceramic in return reduces back pressure..."

Re. no. 1, I can understand the first, but where does the heat go, out the exhaust or partly back into the engine?

Re. no. 2, How does any coating on an exhaust system reduce back pressure?

Thanks for your inputs, I remember ceramic exhaust coatings on E Jags.

AmishWarlord

My Feedback: (5)

Might be a waste of time on a twostroke glow engine.

Might work really well on a steel header of a four stroke.

a1pcfixer

My Feedback: (7)

Should be interesting to read your findings as you progress along with such coatings.

Back in the late 70's-early 80's one of the hot rod magazines maybe Car Craft Magazine(?) took a Buick Regal-Grand National w/turbo, and coated the piston tops, exhaust valve facings, and turbo pipe exteriors with a then new process called henium coating (later prohibited). Their performance results were impressive. You could actually grab & hold onto to turbo pipes! For the uninformed, those turbo pipes are intentionally made of ss and in operation can turn EXTREMELY hot!

I'd hope later versions of similar coatings to have improved.
Biggest downside is naturally co$t.

mrbigg

My Feedback: (21)

Be nice on gassers to reduce in cowl temps.

trappriverpc

The exhaust is able to exit the pipe much quicker because it isn't radiating thru the exhaust walls,  In return the air is able to keep a smooth flow out of the pipe end. This helps the exhaust gas exit the exhaust port without much pressure building up in the pipe.  Hope this helps, as i'm not the best at trying to find the right words for explaining things in detail.

pe reivers

I fail to see how preventing heat radiation can make a muffler system flow more gas. The gasses stay hotter, so have more volume that must exit that same little old stinger tube. Sound waves however travel faster, so a tuned system seems to become shorter by the hotter gasses inside, changing the engine tune.

karolh

Hmmmmm.

Karol

mrbigg

My Feedback: (21)

Read quite a few ads claiming an increase in flow in many car mags.

w8ye

My Feedback: (16)

Mine runs a lot better when I clean all the burned oil and crud off the outside of it.

airraptor

My Feedback: (66)

you would be better off coating the piston top with ceramic and the chamber on the head.


DO NOT coat the sides of the piston unless its a ringed engine larger than a 1.2

captinjohn

I do not know,but I have seen many 2 stroke exhausts painted flat black. I guess the heat is radiated out faster. This may cause less volume inside of theexhaust systemneeded to pass out of it. Just a guess ! Capt,n

a1pcfixer

My Feedback: (7)

Doing the exhaust chamber is an extra cost with little benefit. Only the piston top & exhaust valve face appear to be the areas needed internally.
At least in automotive applications.

The pistons I seen w/henium coatings extended a very, very tiny amount over the face onto the sides. Which I'd assume that the OP/Rich already
knows how far to extend that, seeing as how it's part of his job.

Rich....how far DO you extend such coatings over the top onto the sides of a piston..... round abouts .020-.030 maybe?

pe reivers

True. Gas flow is not an issue though in tuned pipe systems. They are designed for the required flow. Keeping the temperature down may however be required in order not to change the tuned rpm too much.
In speed flight, heating up the pipe is better, so the plane cane take off with cool pipe (low tuned rpm). When the plane gets up to speed and the pipe gets hot tuned rpm will rise to get the best speed. tricky, but it works.

@ MrBigg,
Do you believe advertisements? I rather use my own judgement.

Trinut

My Feedback: (26)

I think the idea is preventing heat radiation keeps the exhaust gas temperature higher. Higher gas temperature has lower viscosity so less flow losses.

mrbigg

My Feedback: (21)

Didn't say I believed them Pe, just what they claimed.

As far as coating on the sides of the pistons go, in the automotive world the coatings I've seen go from the botttom of the oil ring to the bottom of the skirt.

mrbigg

My Feedback: (21)

Here's an image link- [link]http://images.search.yahoo.com/search/images;_ylt=AgiCAW6sCAwk0EBPSLVXVyCbvZx4?p=coated+ pistons&toggle=1&cop=mss&ei=UTF-8&fr=yfp-t-521[/link]

a1pcfixer

My Feedback: (7)

So, what purpose does extending it down there have?

pe reivers

Pistons have a slippery side coat (like molybdenum)  for reduced friction, in order to maximize the mechanical efficiency of an engine.
They also can have a ceramic piston crown coat to keep the combustion heat inside the combustion chamber. Often cylinder heads and valves are ceramic coated as well to get the thermal efficiency maximized.
Many different coatings serve many different purposes.
Exhaust manifolds are coated to keep the gas heat inside, where it can do no harm to engine compartment components on the outside.
Springs are coated to reduce spring surge, spring disks have again different friction coatings

jquid

When you have an exhaust pulse, the gas "bubble" we will call it is hot and expands as it enters the muffler chamber. If the heat radiates outward and soaks the pipe, the pipe itself becomes just as hot as the exhaust bubble. Now if you can keep that bubble intact (heat portion) of it, it will expand down the length of the muffler not outward. Why is this important? As the gas expands down the length, it speeds up. This creates a scavenging effect in the exhaust port. It creates a vacuum which allows expanding exhaust gas to fill this void. Then on the intake side, you have less back pressure of the exhaust pulse to push against, and theoretically more power. Sounds like the reason a tuned pipe works too. Coating a RC .25 may not do a darn thing for performance, especially if you runt he thing lean. But for the cowl temps, this would help reduce rubber deterioration of engine mounts, for example.

On the Buick, you want to keep the exhaust gasses flowing out as fast as possible, because that expanding gas bubble traveling down the header spools up the turbo quicker. If you use all the heat energy heating the manifold, you have less pressure to spool the turbo. Use the heat energy to expand the gasses, and run out faster. You create the scavenging there too with a properly designed header. If the header is designed proper, you get the engine to fire off each piston and each exhaust pulse should meet one after one another in the header. Kind of like a train. An improper designed header will let 2 exhaust pulses merge together, and you get one hot bubble, then a cool one, and the exhaust flow is not constant.

Again, helps the Buick in performance, us maybe no so much. But depending on color, can add a cool factor. A nice wrinkle black muffler would look cool, or a ceramic grey? and be cooler to touch.

Firepower R/C

My Feedback: (10)

I had a thought... I bet the coating would help a smoke system work better. The hotter the exhaust, the better! It might really help out 2 stroke glow engines get better results.

Ceramic smoker mufflers!!! It would give a smoke muffler a bit more novelty. Patent pending hee hee

kenh3497

I didn't read every post so forgive me if this has been covered.....

On a "regular" glow two stroke muffler, the ceramic coating may not provide any benefit except it would look pretty. Now a tuned pipe would be a different story as the pipe needs heat to make it work. A four stroke muffler/header would be an ideal subject as would a gasoline two stroke muffler/tuned pipe set up.

I say go for it and post some photos of the finished product. I assume different colors are available???

Ken

pe reivers

+1 for smoker mufflers
+1 for cooler in-cowl environment.
-1 for "tuned pipes need heat": they dont. Heat just makes the pipe longer for resonance.

pe reivers

double post removed

airraptor

My Feedback: (66)

Pe is dead on in that the reason the exhausts are coated on cars was to keep the under hood temps down. this came about with the Turbos added to cars for performace.

On a normal two stroke likes yours keeping the heat in the muffler could cause a larger power loss than the the gain of the exhaust flowing out faster if it will in those little mufflers. most mufflers on our engines help to take heat away from the engine. All most all r/c engines will use about 70% of the fuel 30% is wasted to heat. i know in cars its 33% to making power 33% to heat and 33% to friction.

Apc1fixer those two you talked about do help but coating the COMBUSTION chamber will help make more power by a couple of ways. reducing the heat soaked up by the block then the cooling system what ever it is allowing the engine to be run a bit leaner. 2. it will keep more of the heat in the chamber which will increase the pressure (force ) applied to the piston making more power.

Anyway to the OP I know the gains that can be had by coating parts and all can you send me an email with your company and i would like to work with you on some items.



also every one on your cowled in engines reducing the heat in the cowl with gas engines you will see a gain in aircraft performance if you get the mufflers/headers coated in that you will have a reduced heat soak in the engine. Also If you coat the top of your piston, have your Combustion chamber coated and have the cylinders coated with the black heat coating you will greatly reduce your engines running temps. so much so that you will have to retune your needles...........