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.
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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
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