: Ceramic coated exhaust manifolds?

07-27-11, 09:29 AM
I recently found out that there's a place literally a stone's throw away from my house that does ceramic coating, so the thought of having my manifolds coated while my engine is out of the car crossed my mind. I've read that this is popular for decreasing under hood temps and emissions, while at the same time giving you a bit more power from the increased exhaust temperature (which I find debatable, and would need to see some dyno results to believe). I know it's done on some high performance or racing applications, so I wondered if it would have any benefits for our Northstars.

So does anyone have any pros/cons, comments or thoughts on this? I figured if I can get it done reasonably it might be worthwhile.

07-27-11, 10:27 AM
No opinion either way - it looks nice, but you can't see our exhaust manifolds anyway. Coated manifolds keep a bit more heat in the exhaust gas, so they would be a plus in a turbo install, but probably no advantage in our NA engines.

Maybe JetHot has some advertising pros and cons in their site.

Back in the 50's, 60's and 70's Jaguar exhaust manifolds were coated with shiny black baked porcelain. Very elegant.

07-27-11, 11:46 AM
I suppose that since there's a lack of application specific information, I wouldn't mind being the test mule. If the place near me is reasonable (I can ship the manifolds to a shop in Memphis to get them done for $200, the local place would have to at least match that), then I'll get it done just for kicks and giggles. I'll consider any benefits to be gravy.

07-27-11, 11:53 AM
My understanding of the theory is that the hotter you can keep the exhaust gasses the better, this aids in velocity and scavaging of the exhaust. On the outside, the cooler you can keep the engine compartment and the cooler you can keep your heads, the more power you can potentially make.

All that being said, I wouldn't do it. You'll spend money without any mearsurable improvement.

My personal experience: I put header wrap on a high 11s street car. I'm sure the theory was working and I know my firewall was cooler than before. However, I noticed no marked improvement at the dragstrip (measurements into the thousandths).


07-27-11, 11:56 AM
If your itching to modify the manifolds, consider getting them extrude honed. I believe even that would only yield a small gain for the investment though.


07-27-11, 12:34 PM
According to the Fiero people the only worthwhile thing to do to the manifolds is to smooth the welds at the flanges. They didn't mention ceramic coating though.

GM extrude hones the exhaust ports on the cylinder heads of the 4.4L LC3 Northstar, so that might have some benefit to our engines. But that's way more invasive than I want to get in to.

07-28-11, 06:01 AM
"GM extrude hones the exhaust ports on the cylinder heads of the 4.4L LC3 Northstar, so that might have some benefit to our engines".

Now that is interesting to know.......

In my disassembly of the motor, I was really intrigued by the cylinder heads, They didn't seem bad, but I didn't like the export opening, or the exhaust manifold flange opening.

Then there is the "Y" cross over pipe with the usual 1/2" - 1" piece of metal inside the pipe blocking exhaust flow. All this is confirming what I've known about most domestic vehicles, they are exhaust restricted.

07-28-11, 09:28 AM
I suppose if you had the intake and exhaust ports on the heads and exhaust manifolds extrude honed and cleared the restriction in the Y-pipe you could potentially free up some power, but it probably wouldn't be anything to write home about. Maybe 10 horses? And that's being optimistic. Maybe if you combined that with the Corsa cat-back on a Deville or Seville you might see some noticeable differences, but until someone actually does it, it's all speculation.

We're probably not the first people to think about this, it's likely that no one's done it before because they decided it wasn't worth the cost or trouble. And they might have been right.

07-28-11, 10:24 PM
Within the last 5 months there have been two threads of Northstar overhauls in which the owner Dremel-tooled out the front Y/crossover excess pipe in the Y. With pictures of before, during, and after. There was no dyno comparison done...........

The intake and exhaust ports are already plenty clean and flow the correct pattern to/from each of the four valves per cylinder. The left bank (Bank 2) crossunder pipe itself is the bugaboo.

"Hog it out, make it bigger and stick loud mufflers on it" IS NOT the formula for better air and exhaust flow. Not by a long shot. Remember: Port size and design also insures air and gas velocity rates - open the ports without accompanying fuel rate and management control and you LOSE POWER.