Exhaust Coatings

Wildman said:
Well which one reduces the heat BEST? I really don't give a hoot about the supposed HP increase I just want to cut down on under hood heat temps.
I've read more people complain about header wraps than ceramic coating but I am not going to argue that they all have their own issues.
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Hi,
I have ceramic and this ha reduce heat load.
Lee
 
I went over and picked up my exhaust from Performance Coatings and snapped some pictures of the different colors they offered.

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@cpwolf Here is their chrome they do. These are the headers for a BBC drag car

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And then here are the mufflers.

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And a close up of the headers.

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This is an older set of headers where they had rusted before.

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You can see the intake manifold on the floor too. I found out I could have had my gears coated too to help reduce the heat.

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If you are Cerakoting exhaust for heat reasons, specifically ask for "Piston Coat". It's the same as regular cerakote but with lower emissivity, meaning it has maximum heat retention capability, and will provide the best thermal barrier.

I had a local shop do an exhaust header inside and out, as well as the intake header and catalytic converters on the outside only. Haven't road tested it yet, but so far I've seen a massive reduction in heat at idle.

My infrared thermometer seems to significantly underestimate the surface temperature, so it must actually have lower emissivity than the default setting of the thermometer.

Lower emissivity also means lower absorptivity in the same infrared frequencies, so coating the intake header should also have some effect on intake air temperature.
 
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DWR said:
Curious if you felt any difference in power with the intake, exhaust being coated, and the insulation on the intake tube? I feel like the answer is a hard maybe, when in hot hot summer temps lol.
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So far, seems to have been a modest improvement. The Windstar intake made a huge difference, far more than I expected. I've made a number of changes beyond just the ones here and the Windstar intake, but I've managed to boost fuel economy from around 12 MPG to 15-16 MPG (6-speed Rubicon on 35x12.5 and heavy everything) altogether even before these items. I don't have good data for after the coated headers were installed yet.

The big issue the TJs have is that higher air intake temperatures lead the computer to pull timing aggressively, meaning less power is made for the same fuel burnt. If you can get the computer to pull timing less, you can get major gains in torque and fuel economy.

That said, you can't just go in with a tuner and tune out the timing modifiers without doing anything else since they actually have a purpose. They are there to prevent preignition and detonation in the cylinder to protect the engine at the price of power and fuel economy.

If you can (1), increase the threshold for preignition and detonation, and (2), convince the computer that preignition or detonation is not a risk, you can get pretty significant gains in torque and fuel economy. By itself, the computer will recognize the colder air coming in the intake, and as a result, pull timing less. But it won't recognize colder manifold air, since the computer estimates manifold air temperature based on IAT, ECT, and a few other factors. However, you can in fact change the tune to account for the lower MAT from coated intake and exhaust manifolds and get extra gains that way without much risk to the engine.

In short, it all has to work together as a system. Simply slapping a header on is going to net you very little. But a properly built intake and exhaust system with an appropriate tune can net you quite a lot.

Colder IATs will also directly increase power to a small degree by providing more dense air to the engine. The engine will provide more fuel to compensate, so you will get a proportional increase in WOT torque, but it also makes the engine less efficient at partial throttle due to pumping losses. In this case, denser air is a net gain if it allows you to hold a lower gear, but is otherwise a net loss at partial throttle. (This is why some highly efficient cars actually have a warm air intake.)

Note that I attribute the vast majority of my gains to getting the engine to pull timing less, not due to the denser air.
 
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Steel City 06 said:
So far, seems to have been a modest improvement. The Windstar intake made a huge difference, far more than I expected. I've made a number of changes beyond just the ones here and the Windstar intake, but I've managed to boost fuel economy from around 12 MPG to 15-16 MPG (6-speed Rubicon on 35x12.5 and heavy everything) altogether even before these items. I don't have good data for after the coated headers were installed yet.

The big issue the TJs have is that higher air intake temperatures lead the computer to pull timing aggressively, meaning less power is made for the same fuel burnt. If you can get the computer to pull timing less, you can get major gains in torque and fuel economy.

That said, you can't just go in with a tuner and tune out the timing modifiers without doing anything else since they actually have a purpose. They are there to prevent preignition and detonation in the cylinder to protect the engine at the price of power and fuel economy.

If you can (1), increase the threshold for preignition and detonation, and (2), convince the computer that preignition or detonation is not a risk, you can get pretty significant gains in torque and fuel economy. By itself, the computer will recognize the colder air coming in the intake, and as a result, pull timing less. But it won't recognize colder manifold air, since the computer estimates manifold air temperature based on IAT, ECT, and a few other factors. However, you can in fact change the tune to account for the lower MAT from coated intake and exhaust manifolds and get extra gains that way without much risk to the engine.

In short, it all has to work together as a system. Simply slapping a header on is going to net you very little. But a properly built intake and exhaust system with an appropriate tune can net you quite a lot.

Colder IATs will also directly increase power to a small degree by providing more dense air to the engine. The engine will provide more fuel to compensate, so you will get a proportional increase in WOT torque, but it also makes the engine less efficient at partial throttle due to pumping losses. In this case, denser air is a net gain if it allows you to hold a lower gear, but is otherwise a net loss at partial throttle. (This is why some highly efficient cars actually have a warm air intake.)

Note that I attribute the vast majority of my gains to getting the engine to pull timing less, not due to the denser air.
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I hear you, I’m fully aware that tuning is a part of the trifecta if you will… I do aftermarket tuning on the side myself. I was curious if without a tune it seemed peppier, but sure as heck knew with a proper tune it would… even completely stock.


I need to upgrade my tuner device before I can tune the jeep lol… thats why.
 
Steel City 06 said:
So far, seems to have been a modest improvement. The Windstar intake made a huge difference, far more than I expected. I've made a number of changes beyond just the ones here and the Windstar intake, but I've managed to boost fuel economy from around 12 MPG to 15-16 MPG (6-speed Rubicon on 35x12.5 and heavy everything) altogether even before these items. I don't have good data for after the coated headers were installed yet.

The big issue the TJs have is that higher air intake temperatures lead the computer to pull timing aggressively, meaning less power is made for the same fuel burnt. If you can get the computer to pull timing less, you can get major gains in torque and fuel economy.

That said, you can't just go in with a tuner and tune out the timing modifiers without doing anything else since they actually have a purpose. They are there to prevent preignition and detonation in the cylinder to protect the engine at the price of power and fuel economy.

If you can (1), increase the threshold for preignition and detonation, and (2), convince the computer that preignition or detonation is not a risk, you can get pretty significant gains in torque and fuel economy. By itself, the computer will recognize the colder air coming in the intake, and as a result, pull timing less. But it won't recognize colder manifold air, since the computer estimates manifold air temperature based on IAT, ECT, and a few other factors. However, you can in fact change the tune to account for the lower MAT from coated intake and exhaust manifolds and get extra gains that way without much risk to the engine.

In short, it all has to work together as a system. Simply slapping a header on is going to net you very little. But a properly built intake and exhaust system with an appropriate tune can net you quite a lot.

Colder IATs will also directly increase power to a small degree by providing more dense air to the engine. The engine will provide more fuel to compensate, so you will get a proportional increase in WOT torque, but it also makes the engine less efficient at partial throttle due to pumping losses. In this case, denser air is a net gain if it allows you to hold a lower gear, but is otherwise a net loss at partial throttle. (This is why some highly efficient cars actually have a warm air intake.)

Note that I attribute the vast majority of my gains to getting the engine to pull timing less, not due to the denser air.
Click to expand...

Exactly. Very well explained, Steel.

Personal experience. When I built the Hemi, I needed a custom tune before starting it for the first time. So at first I slapped an air filter directly on the intake assembly to get it running for a chassis dyno tune. The big Hemi makes a crazy amount of heat, the IAT’s were well into the 200’s, and the ECU was pulling lots of timing to compensate.

Knowing it was a problem, I built and installed a cowl intake, getting the IAT’s very close to ambient. I then had it dyno tuned again. The difference was huge - 50 ponies at the wheels.

I also run ceramic coated (inside and out) headers to help with the under hood temps.
 
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