Ceramic coating, anyone done it?

[FNK]

Does anyone coated the inside of the exhaust manifold whit a ceramic coating to keep the heat inside.

I do think the gain would be noticeable as the velocity would be greatly enhanced!
As much as having an exhaust leak on a N/A engine. Just having a hole in the flex pipe killed most of the performance!

[JumboBlack1.8]

I'm no expert on thermodynamics or air velocity, but I do believe that ceramic coating the INSIDE of a manifold would be counter-intuitive. Inside the manifold, you typically want your air velocities to be high (or higher than stock for performance purpose). From what I understand, this is achieve partially by smooth surfaces along the paths where air travels. The smoother the surface, the faster the air is capable of traveling (i.e. reduced resistence). This is why porting (increasing the size of intake and exhaust ports to increase air volume) and polishing (smoothing the ports/reducing any points of resistance in the intake and exhaust tracks) are CRUCIAL/popular options when deciding to increase air-flow in either your intake or exhaust manifolds, or cylinder heads.

Now, your theory on ceramic coating to increase exhaust temps to further increase exhaust velocity is theoretically good. However, the reason why ceramic coating the INSIDE is a bad idea, is because it doesn't create that smoother surface that we're looking for (not to mention that it'd be pretty hard to coat the inside of a manifold evenly). Thus, you'd be creating even more grooves within your manifold that will disrupt the flow of air. Though small these grooves might be, they wouldn't offer an improvement over going with a stock, unaltered manifold, IMO. While you might get some of the heating benefits of the coating, you'd be losing out of airflow.......But, ceramic coating the OUTSIDE is what you'd want to do. Then, if you'd got the time, money, or know-how....polishing and port the inside of the manifolds.

[terraflata]

IMHO

Ceramic coating is good in the sense that it reduces the transfer of heat from the exhaust gases to the manifold (the hot side of you turbo can also be ceramic coated as well as exhuast parts). Reducing that transfer of energy allows it to be directed towards turning the turbo (better or possibly smoother response). Depending on the coating I would say that it allows the maifold to run cooler as well, reducing the extremity of it`s heat cycle, possibly (and most likely) increasing the durability of the manifold, by reducing the wear. And of course ceramic coating is an excellent way of reducing underhood temperatures, helping to lower IATs.

[FNK]

Well in the case of porting, the turbulence in the air is considered minimal vs the exhaust near the piston.

And why the coating inside, well because the heat wouldn't be transfered to the metal. Heat wouln't make the iron expand to crack the coating and the casting it self.

Im asking because I'll probably have to pull the engine next summer for various work, while out, I'm planning custom performance job.

[Dynamite]

I agree with jumboblack, If you were to ceramic coat the inside of your mani then you would cause a increase in turbulence in the manifold, this disruption will cause the gasses to flow slower not faster and cause more back pressure, unless you could somehow get the ceramic coating then polished inside the mani. the other down side is that it will have a finite thickness, this will take up area in your manifold so it will flow less, it will mean the mani dose not flow as well, so a loss of power will be caused by the increased restriction causing more back pressure. The principle of keeping the gas as hot as possible inside the exhaust mani is most defiantly correct but whether ceramic coating on the inside causing it to retain heat better and hence higher velocities will out way the downside of increased turbulence causing slower velocities and lower flow and decreased area that will increase the velocity and decrease the flow is up for debate. If you are that way inclined I can have a look in my thermo books when I get a chance and see if i can find the maths for you to go through if you want. Given the complexities of the shapes in the manifold though my guess is that you will need to write a program in math programing language to solve them with enough accuracy to get an answer that means anything. It would probably be quicker just to dyno the car then do it and dyno again with out changing anything.

[FNK]

Coding a whole program in Matlab or Maple is not my goal...
The coating itself is not that thick, but I wonder about that finish... How much "Ra" could it be?

[v dub'n]

When coating something the right way inside and out gets coated, the inside coating keeps the runner from absorbing the heat. When I build my next motor I will be coating the compustion chanmbers and. Exhaust ports.

[Dynamite]

hmm interesting, has it been documented before? im keen to have a look

[terraflata]

All I know if my manifold, turbo, wastegate, downpipe, and exhaust are all being ceramic coated. I dislike underhood temps and cracking pieces that cost lots of money.

[terraflata]

Here. Did a search this is what turns up, might change some ideas.


"Anyone who still runs painted headers is a flake! Factory-applied header paints have about a five-minute post-installation life span. From a longevity standpoint, paint just can’t stack up against high-tech ceramic coatings. But ceramics don’t come cheap, selling for up to twice the price of a set of painted headers. For some, the added surcharge might be hard to justify if it was just a question of looks alone.

However, ceramic coatings’ appeal is more than just the pretty wrapper. One of the leading exhaust coating outfits is Jet-Hot Header Coatings. Jet-Hot Sterling, its standard product, is a third-generation, aerospace-derived metallic-ceramic coating compound consisting of a proprietary, baked-on mixture of aluminum, ceramic, and sterling silver powder. The unique combo provides both high luster and good flexibility—if hit by a hammer, this ceramic won’t shatter like your toilet-bowl would. There’d be a dent, for sure, but the surface won’t break—an obvious advantage from both in-car installation scrapes and anti-corrosion standpoints.

Jet-Hot points out that realizing the full anti-corrosion benefits of header coatings requires coating the headers on their inside as well as outside surfaces. Not all competitors coat the inside surfaces, which isn’t good because exhaust gases themselves contain corrosive compounds. If the inside isn’t coated, the header eventually rusts through from the inside out. Coating only the outside can also cause another problem: Mild steel tubing fatigues when it gets too hot. An outer-only thermal barrier blocks the heat from radiating through the exterior metal surface, while the lack of an inner barrier exposes the metal to added “trapped” heat. In a scenario reminiscent of that caused by the dreaded “curse of the mummified headers” (outer cloth wraps used by some racers), the result can be literal disintegration of the mild-steel tubing.

The aluminum portion of Jet-Hot Sterling’s compound starts to melt at temperatures over 1,300 degrees F, but that’s OK for 90 percent of the applications out there. Cars running heavy loads of nitrous, a supercharger, or a turbo may need to move up to Jet-Hot 2000, which protects metals up to their melting point or 2,400 degrees F (whichever occurs first). The drawback is that Jet-Hot 2000 only comes in dark colors so it’s not as pretty. But the good news is that Jet-Hot 2000 usually eliminates the need for pricey (and hard to weld and fabricate) stainless steel tubing often specified in high-zoot nitrous or turbo applications.

The ceramic coating’s ability to trap heat aids a marginal engine coolant system in a closely cowled musclecar by reducing underhood temperatures. And as installed in a real car, lowering the ambient temperatures could also allow a cooler, denser fuel/air charge to reach the combustion chambers, offering more power-making potential.



By retaining heat within headers, the coating is also said to increase exhaust-gas velocity because hot gasses expand and travel faster. By smoothing the internal header bore surfaces, turbulence is reduced. The net result is more effective cylinder scavenging, which yet again offers a potential power increase. We recently had the opportunity to evaluate the effectiveness of Jet-Hot Sterling-coated headers on the Westech engine dyno. Like most header companies, DynoMax offers both painted and coated headers. It uses Jet-Hot as its coating supplier. DynoMax’s painted headers are sold under its Blackjack trademark, while the coated versions are marketed as Cyclones—but other than trade name and finish, the header designs for the same application are identical.

In our test case, the application was a GM 454 H.O. Gen VI big-block crate motor, officially rated at 425 hp and run as-delivered with a 750-cfm Mighty Demon carburetor. Tested on Westech’s SuperFlow dyno, the engine made about the same power and torque with both painted and Jet-Hot–coated header sets (see table). The numbers varied by less than 1 percent, within the dyno’s margin of error. Thanks to a wide-open dyno cell and hurricane-like air circulation fans, heat wasn’t trapped as it would be in a real car’s engine-bay. Engine coolant temperatures stayed under 155 degrees F, well below those encountered in a typical street car on a hot summer day. The absence of real-world “hot-soak” conditions probably accounts for the similar power and torque outputs in this case.

Header surface temperatures were a whole ’nother story, however. We checked header-tube surface temperatures both at idle and—in an attempt to simulate part-throttle, sustained cruise conditions—at 3,200 rpm with a light, 60 lb-ft load applied to the dyno’s water-brake. In both cases, the coated headers cut the painted set’s surface temperatures by over 50 percent. In a real car, this would significantly reduce both coolant and underhood temperatures. In the dyno-cell, we could actually touch the coated headers with our bare hands within 5-7 minutes after engine shut-down!

Headers aren’t the only parts that benefit from Jet-Hot coating; it can also be used on exhaust pipes, mufflers, and even (for emissions-reducing quicker light-off times) the catalytic converter. By applying Jet-Hot only to the top and bottom intake manifold surfaces, as well as the outer surfaces of turbocharger ducting, centrifugal supercharger ducting, and fuel-injection system air-intake tracts, you can keep incoming air and fuel cooler by insulating the charge from radiant engine-compartment heat. Yet headers remain the most common everyday application, and this test indicates that for the temperature reductions alone, this strong, durable, and “cool” coating is well worth the extra bucks."
Original Source: Car Craft

[Dynamite]

hmm interesting, they didnt really find any performance advantage, but it kept the temps well down in the engine bay. I guess it would be worth doing just for that, depending on the cost. Especially if you were using tube headers rather than cast ones, I really dont see the rusting through thing to be an issue on cast manifolds.

[FNK]

Awesome source!
So 1% in a controlled environment still mean 2hp on my car.
In a hot day, or even in winter, the positive impact on performance would be even greater!

Google "Jet-Hot–coated" only return sites from forums and reviews... HOW TO BUY IT! haha

[terraflata]

hmm interesting, they didnt really find any performance advantage, but it kept the temps well down in the engine bay. I guess it would be worth doing just for that, depending on the cost. Especially if you were using tube headers rather than cast ones, I really dont see the rusting through thing to be an issue on cast manifolds.

Rust issues are usually never problems on tubular manifolds either because they are almost always made from SS. But the protection it would have from cracking and such due to less aggressive heat cycles is what really interest me. Such a small cost to protect something like a -/+ $1000 manifold.

[Doug@FrankenTurbo]

Both of these are good.

• http://www.techlinecoatings.com/hi-performance/
• http://www.nicindustries.com/thermal_barriers.php