Engine & Header Coating Technology - How It Works

Jet-Hot explains the technology and science behind header and engine coatings, and the benefits they offer in power and durability.

Stephen Kim Aug 24, 2012 0 Comment(s)
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In the walk of the hot rodding aftermarket, the term battle tested serves merely as a euphemism for track-tested racing hardware. When the products at hand are Jet-Hot’s well-known ceramic coatings, however, that euphemism transforms into a literary truth. Before entering the automotive market, Jet-Hot earned its red, white, and blue stripes developing coatings for the U.S. military. Whether the challenge at hand was providing a thermal barrier on fighter jet engines and submarine parts, or protecting the launch gear on aircraft carriers, Uncle Sam turned to Jet-Hot to get the job done during the heat of combat. Recognizing the benefits of Jet-Hot coatings, the Army began using them on armored vehicles as well.

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Eventually, Jet-Hot pondered the benefits of applying its proven coating technology to automotive applications. After extensive research, the company developed coatings specifically for automotive use, and racers and enthusiasts alike quickly realized the benefits of Jet-Hot’s ceramic coatings. In the past, header coatings were nothing more than aesthetic products that provided little to no thermal protection, but Jet-Hot changed all that by offering coatings that not only prevented corrosion, but also looked great. In recent years, engine builders have realized the benefits of applying Jet-Hot’s thermal coatings on internal components such as pistons and cylinder head combustion chambers. Furthermore, the company has also developed a complete line of antifriction and oil-shedding coatings. To get the full scoop on coating technology, and how hot rodders can use them in their own rides, we recently sat down and chatted with Jet-Hot’s Dave Burton. Here’s what he had to say.

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Origin of Coatings

Coating technology was first applied to headers in 1981. The technology was an adaptation of similar coatings Jet-Hot developed for the aerospace industry as a means of protecting high-temperature metals from oxidation. The extreme heat created by fighter jet engines, the corrosive environments they operate in, and the countless heat cycles they’re subjected to caused very rapid parts wear, so the military turned to Jet-Hot to develop coatings that extended component longevity. Furthermore, Jet-Hot has supplied proprietary coatings to protect the parts on aircraft carrier launch systems for the U.S. Navy, as well as coatings for the U.S. Army’s armored vehicles. Leveraging upon years of experience learned from providing long-term protection from corrosion and thermal fatigue in military applications, Jet-Hot transitioned into the automotive aftermarket in the early ’90s. These coatings are similar, but have been updated and enhanced over the years to meet the specific needs of the automotive segment. Jet-Hot is constantly developing and testing new coatings for specialized applications and solutions. Customers can rest assured that Jet-Hot uses the same technology in our automotive applications as in our military applications to provide a superior level of protection.

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Automotive Transition

Given Jet-Hot’s extensive track record in heavy-duty military applications, we began exploring how to apply our coating technology to address the heat management issues in hot rods and race cars. After releasing our first automotive products, Jet-Hot became the number-one coating brand on the market within five years. Enthusiasts also appreciated the high-sheen finish provided by our coatings. In the early ’90s, Jet-Hot became the only coating company to support racers at the track. Legendary NHRA Funny Car champion John Force recognized the safety benefits of Jet-Hot coatings early on, as they substantially reduced header temperatures. His crew chiefs discovered that Jet-Hot’s coatings allowed for quicker cooldown periods, allowing them to rebuild their race motors more quickly between rounds.

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Coating Makeup

Ceramic is a rather generic term that doesn’t necessarily describe the makeup of a coating. All coatings are not created equal, and several elements go into Jet-Hot’s coating that give it its heat and corrosion resistance properties and distinguishes it from the competition. At a glance people only see the aluminum part of a coating. Ceramics in general are compounds that are inorganic and nonmetallic. Since organic compounds contain carbon that burns under extreme heat, eliminating them from a coating is very important. This is what makes ceramic coatings different from a powdercoat or epoxy, both of which have carbon bonds that start breaking down at 600-800 degrees F. Additionally, ceramics contain binders that hold everything together. A coating’s filler material can be a pigment, paint, or aluminum. Using aluminum in our coatings allows polishing it to a high-sheen finish that enthusiasts are familiar with. The end result is a coating that not only offers high-temperature and corrosion resistance, but also looks great.

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Coating Process

Jet-Hot’s ceramic coatings can be applied to any set of headers, both old and new, and are backed by a lifetime warranty. After receiving the parts at our facility, they are inventoried into our computer and scribed with the order number on the pipes themselves. We also take a photo of every incoming order for referencing purposes. The next step is cleaning the parts. Usually a thermal degrease or chemical bath works well for light oils, oxides, and other contaminants. Internal engine parts, like pistons, are hand-cleaned with solvents or by using an ultrasonic process. The parts are then grit-blasted to remove scale and debris, and to get the parts down to a clean “white” metal surface. This gives the coating more surface area to grab onto, and ensures good bonding. Once the metal has been cleaned, the ceramic coating is applied using a spray gun similar to those used by body shops. After curing in an oven, the parts may get coated again, if necessary, before they are submerged in a tub of polishing media. The polishing stones vibrate across the metal surface to give the parts a nice sheen, and the parts are then hand-wiped before moving on to final inspection. From start to finish, the coating process takes about two days.

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Inside and Out

It’s not uncommon to only coat the outside of a header, but at Jet-Hot we feel it’s important to coat the inside of the header tubes as well. There are several advantages of doing so, which is why we coat all headers on both the inside and outside. Since water vapor is a combustion by-product, as a motor and exhaust system cools down, water condenses and rusts a header from the inside out. To prevent this, Jet-Hot has developed special fixtures and techniques to apply our coating to the inside surface of header tubing. Regardless of how complex the inside of the tubing may be, we have developed methods to apply coatings to them. Additionally, this yields the benefit of reflecting heat away from the inside surface of the pipes. By reducing the amount of heat transferred through a pipe from the inside out, it keeps the outside header surface cooler as well. Superior heat retention also assists in improving airflow and exhaust scavenging. Furthermore, by ensuring that the heat travels more uniformly across the header surface, it eliminates the potential for heat to build up in localized hot spots. Jet-Hot does not charge extra for this work and provides a full interior coating on all parts. Coupled with a full lifetime warranty, Jet-Hot stands behind its coating and workmanship.

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Jet-Hot offers several different coating options: Extreme 1300, Extreme 2000, and Extreme 2500. Extreme 1300 is by far our most popular coating. It is easily identified by its polished aluminum finish, and is capable of providing continuous protection to a skin temperature of about 1,300 degrees F. This makes it ideal for naturally aspirated motors, and it can be applied to the majority of parts that we see. The next step up is our Extreme 2000 coating; it contains stainless steel elements that provide thermal protection to skin temperatures of about 2,000 degrees F. This type of coating is best suited for applications with turbos or superchargers that run very hot. Finally, Extreme 2500 is a full ceramic material that provides the best level of insulation for any application. As its name suggests, it can withstand skin temperatures of about 2,5000 degrees F. It contains no metal content at all, can only be applied to the outside surfaces of parts, and is often used on components located downstream of turbochargers.

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Turbo Applications

Many people are already familiar with the benefits of ceramic header coatings in naturally aspirated engines, but they offer advantages in turbo applications as well. Due to the extreme heat generated by turbo motors, Jet-Hot recommends using our Extreme 2000 or Extreme 2500 coatings in turbo applications. Coating the hot side parts can maintain the heat inside components better for improved thermal efficiency. Furthermore, our coatings help spread the heat out more uniformly. Interestingly, in rear-mount turbo combinations customers have reported reduced turbo lag when using Jet-Hot coatings.

Coating Maintenance

One of the biggest benefits of a coated header is its shiny good looks, but as the miles and years tack on, regular maintenance is required to prevent dulling and staining. Jet-Hot recommends that customers periodically clean their headers to remove any salt or road grime that can accumulate on the surface. The best way to do this is with light soap and cool water. Oil, transmission fluid, and engine coolant can be easily removed with fine steel wool or a Scotch-Brite pad. Any nonabrasive polish can then be used with a soft cloth to bring out a high-luster finish.

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Aluminum will cloud up when cleaned in a hot condition, so it’s imperative to allow the surface to cool down first. If headers are dulling, the coating is getting too hot for the application, or there is residue that’s causing the color change. Furthermore, uneven fuel distribution and improper spark timing can result in extreme exhaust gas temperature that may exceed the temperature range of a coating. To avoid this, it’s important to make sure an engine is in optimal running condition. Jet-Hot customers can also rest assured that their header coatings are covered by a lifetime warranty. If there’s ever a problem, just ship the headers in and we’ll re-coat them under warranty.

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Internal Thermal Coatings

With racing classes as competitive as they are these days, engine builders are increasingly using coatings on internal engine components to search for extra horsepower. In addition to exhaust coatings, Jet-Hot also offers coatings for internal engine components such as pistons, crankshafts, and bearings. Internal engine coatings fall into three categories: ceramic metallic thermal coatings, friction reduction coatings, and oil-shedding coatings. Ceramic coatings are often applied to piston crowns, valve faces, and the cylinder head combustion chambers. This provides thermal management and helps retain heat in the combustion chamber for improved power.

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Antifriction Coatings

Friction reduction coatings provide improved lubrication and cooling to extend the life of internal engine components. On bearings and piston skirts, fluoropolymer coatings are designed to help maintain the oil film on the surface. The benefit is reduced friction, improved longevity, and increased horsepower. The coatings are very effective, yet thin enough that they don’t impact bearing or piston-to-wall clearances at all. While the purpose of ceramic coatings on the valve faces is to maintain heat in the combustion chamber, an antifriction coating can also be applied to the valve stem. The resulting friction reduction can help prevent engine damage caused by sticking a valve.

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Oil-Shedding Coatings

Engine oil not only lubricates parts, but it also carries heat away from internal components. Oil-shedding coatings allow oil to perform its job by carrying that heat away more efficiently. As such, oil-shedding coatings are typically applied to valvesprings, and the inside surfaces of valve covers and oil pans. The more oil these components can shed, the more heat that can be carried away. Other favorable characteristics of these coatings are that they’re highly resistant to chemical acids and bases, and improve oil drain-back and oil management.

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Cooler Air Temps

Keeping the temperature of the intake air charge as cool as possible results in a denser air/fuel charge, which increases horsepower. A cooler air intake charge is also more resistant to detonation. While it’s true that header coatings reduce underhood temperature, and therefore the heat that soaks into neighboring components, the intake manifold itself can also be coated. Applying a ceramic coating on the bottom surface of the intake manifold mitigates the amount of heat that will transfer from the hot engine and engine oil into the intake runners. This keeps both the air and fuel cooler. The inside of the intake runners can also be coated, which sometimes improves the laminar flow characteristics of the induction system. In the near future, Jet-Hot plans on conducting extensive dyno testing in-house to measure the performance benefits of our engine coatings.

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Coatings and Welding

Since there are often clearance issues with headers, they sometimes need to be cut, welded, or modified for proper fitment. For the sake of simplicity, it is always best to complete these modifications or repairs before sending a set of headers in to get coated. This eliminates the possibility of having a section of tubing where the coating is no longer present. In the event that a section of tubing that has already been coated needs to be welded, the coating must be removed with a grinder. Likewise, the heat of the weld must be increased as well.

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Coatings and Dynos

When driving down the road, there is always a steady stream of air that removes heat from the engine compartment. However, this isn’t the case on an engine or chassis dyno. The stagnant air in a dyno cell combined with the heat generated by sustained high-rpm engine operation can exceed the limitations of the aluminum in the coating matrix. This can ultimately cause dulling of the coating surface. To avoid this potential problem, it’s best to use a large fan to help dissipate the heat of the engine and headers during dyno testing. CHP

Sources

Jet-Hot High Performance Coatings
800-432-3379
http://www.jet-hot.com
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