Ceramic Coated Manifold Data
-
Along with powdercoating I have started doing thermal barrier ceramic coatings and will soon begin high-emissivity coatings.
The basic theory and application of ceramic coatings is to reduce the amount of energy that escapes through the walls of the header/manifold pipes in order to keep exhaust gas velocity high for exhaust scavenging during overlap on NA engines and to lower your spool rpm on a turbo engine by increasing the energy hitting the turbine.
I will spare you all the boredom of the test procedure and setup but you are welcome to ask any questions you may have if you would like to know more.
Test data for uncoated vs coated is shown below with a 450F input temperature in the port for cylinder 1. Surface temperature @ mid span of tube 1 and internal temperature at the outlet were recorded.
As expected, more heat(energy) made it to the outlet with the ceramic coating.
What wasn't expected was more heat on the surface of the tube.
With the uncoated manifold, the heat was conducted throughout the entire manifold quite uniformly even though the 450F was only being introduced into the tube for cylinder 1. The energy that should be going through the outlet was being equally dispersed throughout the steel and the ambient air both inside and outside of the tubes caused the manifold to act like a large radiator. The tube for cylinder 6, despite being the farthest away from the heat source, was very hot to the touch.
With the coated manifold, the thermal conductivity through the manifold is significantly reduced which keeps much more of the heat(energy) inside the tube for cylinder 1. The energy that used to be conducting freely throughout the manifold was staying in the tube for cylinder 1. With more energy staying in that 1 tube, naturally the outlet temp and the surface temp are going to be higher since the energy concentration is higher.
If the experiment was conducted with heat sources in all 6 cylinders I would expect the uncoated manifold to become thermally saturated and have a much higher surface temperature than the coated manifold.
Evidence of the improved energy containment within the tube is shown below.
A minute after removing heat, the surface temp of tube 1 was 253F. Cyl 6 and the wastegate tube (which contacts tube 1) were very close to ambient. Interestingly enough tube 2 conducted very little heat from tube through the flange or collector as it was only 94F.
Cliffs notes: let me give you horsepower
-
Great info!
Sent from my SM-G900V using Tapatalk
@DrLeadFoot
-
^^^+1
-
How durable is the coating? Think you could use it on the exhaust runner and combustion chamber? Should help with detonation in turbo application. Keeping the heat out of the m20 head should also help keep it from cracking.
-
Very nice!
I am also surprised to see the increase in surface temp after coating!
I assume these are coated inside and out? -
iR thermometer doesn't work on "shiny" did you take actual measurements with a surface probe? Without knowing the "e" of the surface and dialing the IR to that e value you can't directly compare especially when the coating is changing the e on purpose. I've temp'd metal pipe that is 300f but reads 120 because it's averaging in the reflection of the room.
The coating looks awesome. How tough is it and could it be used on wheels?
Sent from my awrPhone using Tapatalk
-
iR thermometer doesn't work on "shiny" did you take actual measurements with a surface probe? Without knowing the "e" of the surface and dialing the IR to that e value you can't directly compare especially when the coating is changing the e on purpose. I've temp'd metal pipe that is 300f but reads 120 because it's averaging in the reflection of the room. The coating looks awesome. How tough is it and could it be used on wheels? Sent from my awrPhone using Tapatalk
That's interesting to know. I'e been using an IR thermometer to measure rotor temps for years now. I think for his purpose right now he can still measure with an IR therm and gather results based on variances.
Why would you want to use this on wheels?
-
If the coating is harder or has a satin or matte finish that is unique it would be cool. Also maybe it adheres better for a more reliable rim seal
Sent from my awrPhone using Tapatalk
-
Hi Andrew, thanks for the info. I will do some research and play with emissivity values that may correlate to higher accuracy results on my next experiment. The coating is more durable than I anticipated it to be, though I like to put a generous surface profile on the parts I prep. It can flake off if it gets chipped. It is a lot like the green coating on brake hard lines.
I dont see why it wouldnt work on wheels although a rock chip would make it vulnerable to flaking moreso than a more flexible enamel type paint
-
I've been using IR thermometers for years. You just plain can't measure the temp of a mirror surface for and example. You will be measuring the temp of the item in the reflection. To measure a soda can for example you have to put on a piece of tape. Same for ductwork. A surface probe thermocouple would be the accurate way to measure but an internal probe into some thermally conductive goo of some type would be a decent makeshift. Only trial n error you can get an accurate e value for the different surfaces but once determined should work well. High temp tape should work well
Sent from my awrPhone using Tapatalk
Hello! It looks like you're interested in this conversation, but you don't have an account yet.
Getting fed up of having to scroll through the same posts each visit? When you register for an account, you'll always come back to exactly where you were before, and choose to be notified of new replies (either via email, or push notification). You'll also be able to save bookmarks and upvote posts to show your appreciation to other community members.
With your input, this post could be even better 💗
Register Login