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There are coatings manufactured for virtually eve...
Advances in Engine Component Surface Finishes
In a recent Engine Builder online poll, 50 percent of respondents said they used some coated parts in most of their engine builds. Surprisingly, however, another 39 percent of respondents said they were not aware of any benefits to using coated parts. Is this a problem – or an opportunity?
By Doug Kaufman
For their part, parts suppliers are often sympathetic to the concerns of engine builders. Alan Davis from Eagle Specialty explains: “There have been a lot of ‘snake oils’ and ‘voodoo’ in the past. Any results you can’t quantify by obvious results on the dyno or by other tests are risky at best.”
Anyone who has been in this industry more than a few years knows that there HAVE been a lot of promises made and not kept. It’s perhaps a, “Fool me once, shame on you; fool me twice, shame on me,” mentality and no one wants to be fooled. However, experts say the benefits to coatings and surface treatments are tangible and offer real opportunities for engine builders and their customers.
“Coatings provide tremendous benefits,” says Leonard Warren, Techline Coatings. “There is virtually no part of the car’s engine, transmission, cooling or driveline system that won’t benefit from coatings it’s understanding them that’s the difficult part. We believe we need to be teachers more than salesmen. Many people are familiar with certain types of coatings because they’ve shown their benefits, but there are so many other benefits that people don’t know about.”
Warren points out the established reputations of header coatings, piston coatings and bearing coatings. Each of these processes has shown significant benefits. Yet, there are still misconceptions to overcome.
“When we talk to people at trade shows or when we are contacted via phone or email we are often struck by the varied responses to coatings,” says Richard Tucker of Swain Tech. “We have companies who we have worked with since 1981 who are as well versed in coatings as we are and they talk about coatings as being well-established ways to gain power and durability. The next contact could be somebody who has never heard about coatings before and wants to learn more. We could then get a contact who says all coatings are junk because he had an engine builder slap on some coatings in his shop. Some say coatings are a waste of money and can ruin a motor. It is interesting how technology that has been around so long and is so well established can have such varied reactions from so many people.”
Tucker attributes much of the misconception to various factors. “I think part of this is due to folks coming and going in the industry. Part is due to the 'do it yourself' kits, which are not likely to produce the same results as sending the parts to a shop that has hundreds of thousands of dollars into surface prep and application equipment. Part of it is due to outlandish claims that coatings will solve every problem you could have with a motor and make huge power improvements. These factors together can prevent good engine builders from seeing the performance benefits of coatings.”
There is a wide range of types of coatings used in today’s engine parts, explains Jesse Elliot, HM Elliot. “Most of the coatings in today’s engine parts are dry film lubricants. These are called wetting coatings, which means that they will hold oil whereas pure Teflon will actually repel oil. The engine coatings are actually composed of a few different materials and PTFE (Teflon) is one of the main ingredients. But when combined with the others it allows the coating to hold the lubrication rather than repel it.”
Lubricant coatings allow the components inside the motor to survive with less oil because there is a constant film always there protecting them, explains Elliot. “The engine can be built with tighter clearances with the use of coatings without fear of damaging critical components.”
Another type of coating is a ceramic thermal barrier coating that can be used on the crown of the piston to prevent heat soak or applied to the combustion chambers and valve faces of exhaust ports and fillets of the exhaust valves. This keeps the heat in the chamber where it is needed most. Ceramic can also be applied to the headers and exhaust systems, keeping the heat contained inside the exhaust system, which in turn speeds up the exhaust gasses significantly.
“The ceramic is also very popular for use on turbochargers where it creates less turbo lag because the faster moving hotter exhaust temps that are retained inside the housing that keep the turbines spooled up, Elliot says. “It is also very good for corrosion resistance, the ceramic we use has gone 6,000 hours in a ASTM B117 salt fog chamber before it starts to show signs of residual rust.”
This variety of requirements, Warren says, is precisely why there is no “one-size-fits-all” in the coating business. “There are coatings manufactured for virtually every engine part including the block and heads. The coatings can be lubricants, oil shedding materials, thermal barriers, thermal dispersants and cosmetic. Many coatings will provide more than one function. As an example two coatings can be combined to allow for used piston skirts to be built up while increasing lubricity. Or, an oil pan can be coated for better oil drain back while also offering enhanced cooling of the oil. Intake manifolds can be coated to reduce intake manifold temperature while improving flow through the runners. Most coatings are a mixture of ingredients designed to enhance the properties of the finished product, but what works well in Top Fuel isn’t necessarily something you would want to put in your street rod,” Warren says.
When we say “coatings,” people often think of a liquid or powder, but other surface treatment processes shouldn’t be overlooked. Coatings and surface treatments aren’t necessarily the same thing, though benefits can be seen from each.
“Coatings are a process where additional material of a different kind is adhered to the surface of a part,” says Eagle’s Davis. “Treatments do not add material, they change the existing material. For example, ESP Armor is an optional surface finishing process available on any new Eagle crankshaft or set of connecting rods. It is not a coating.”
Davis explains that all forged 4340 steel cranks feature a standard nitrided surface finish. “The only treatment we offer as an option is ESP Armor. While ESP Armor looks awesome, it is by no means a cosmetic treatment. What good is a cosmetic treatment for engine parts no one will see once the engine is assembled?”
Davis says that the finishing process his company offers “better perfects the surface finish of the part. It reduces microscopic imperfections that contribute to bearing friction, fatigue failures, and oil retention. It cannot flake off, peel off, wear off, or separate from the crank. The benefits that ESP Armor has is that it reduces bearing friction for an increase in power through improved engine efficiency. It removes pits and valleys so oil slips off the surface more readily to reduce bearing shear friction and counterweight windage.”
In addition, Davis explains, the process also improves fatigue life of the crank or rods by removing ‘starting points’ for stress fractures to begin. “Tests have been performed by us, by various magazines as well as by our customers. All have reported an increase in power from 1-4%. Also reported was the fact that it took longer for the oil to get up to temperature on the dyno. This is a testament to the increase in efficiency of the engine.”
And it’s the testing and proof that engine builders care about most. “To most people, the key benefit is that the surface treatment makes more power,” says Techline’s Warren. “But there are a variety of other benefits: we can reduce operating temperatures; extend part life; improve appearance; reduce maintenance; alter things like timing and tuning in a beneficial way. You can run less timing and broaden your torque curve and actually still make more peak horsepower with coatings once you understand how they work and how to use them properly,” Warren says.
What Should Builders Know?
“Engine builders should remember that if they ever see the coatings wearing off they need not fret because the coating hasn’t completely disappeared it has actually transferred itself over to the other surface material that it is coming into contact with,” explains Elliott. “For example, if an engine builder always uses coated pistons in a motor he is building, especially if it is an engine that is rebuilt over and over, the cylinder walls inside the block will have some of the coating that has been on their piston skirts transferred over and has made for a very nice finish inside the cylinder bores.”
While this is all done on a microscopic level, Elliott says, you can see it with the naked eye if you know what you are looking for. The piston skirt coating and engine bearing coating are both formulated to be somewhat soft so they can lapp themselves into whatever surface they will be rubbing against. “No need to worry... trust that it is still there even though it may not be completely visible.”
Tucker stresses the importance for engine builders to know what they are buying when they consider coatings. “What purpose do they want the coating to serve? If it is a cosmetic coating there are several parts that can be coated directly from manufactures who have integrated cosmetic coatings in their manufacturing processes with great success. If it is performance improving they need to realize most of what you will get from a manufacturer will tend to be a break-in coating, which is good in some applications. However, for those wanting a more permanent coating they would need to consider a shop that specializes in the formulation and application of coatings. We have been offering these performance improving coatings to customers since 1981 and have the specialized equipment and skilled workforce to properly apply materials which are meant to stand up to the abuse a high performance motor may need to endure.”
Tucker explains that “doing it yourself” isn’t likely to be easy or inexpensive, unless you are looking at doing it on a large scale. “At Swain Tech we invest hundreds of thousands of dollars into cleaning, masking, blasting, pollution control and curing equipment. This ensures parts will be properly cleaned, have the correct profile for ultimate bond strength, will be cured in ovens with tight temperature controls to make sure all parts in the oven are properly cured instead of leaving some parts under cured for a poor quality coating or over cured parts that are overheated and lose tensile strength. Pollution control keeps our work areas clean for our employees and our neighbors.”
Warren says engine builders who may be considering coating on a broader scale should do the necessary research by contacting veteran suppliers. A variety of new processes and coatings are introduced each year, and opportunities exist for shops to diversify their operations.
“Any improvement in efficiency is welcome. In addition, reduced part stress and wear stretches everyone’s dollar. Cosmetic improvements are also a benefit of using coatings as several coating systems allow for custom colors and effects to be produced along with reducing or eliminating polishing and cleaning.
“We’ve just developed a new process called ‘DiamonDyze’ that essentially gives an enhanced aluminum oxide conversion layer to any aluminum part,” says Warren. “It gives the wear resistance of Type 3 hard anodizing with a 3-5 micron surface build up in any color you with. It has a tighter pore structure and a smoother surface than hard anodizing, yet can reduce friction, galling, wear, etc.”
Warren explains that, while adding an anodizing line to a business capability will require an investment in the needed equipment and training, he believes that the return on the investment will be well worth the effort.
“Readers should recognize that people are out there who understand the technology and can help them.
“Coatings shouldn’t be looked at as something you need, necessarily, but as something that will enhance the performance and life of a part,” he says. “They can also be used to diversify the base of a machine shop’s income and have more opportunities to do more work and make more money, in many cases using equipment you already have.”
But whatever your interest in involvement with surface treatments whether on an application or installation basis the important thing is to keep your mind open about the potential that exists in your own shop, say our experts. The education starts by contacting manufacturers and taking advantage of the resources available, because they’re missing tremendous opportunities in making money, improving the product line, benefiting their customers and creating a better reputation.