eliminator - engine coatings · 2018. 10. 23. · 22 july-sept 2014 engine professional engine...

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Engine CoatingsAn updated look at various coatings applicable for engine builds.

BY MIKE MAVRIGIAN

A variety of “coatings” are available for both internal and external engine components, withapplications varying from power enhancement, engine efficiency and durability/longevity tocorrosion protection and external appearance. Here we’ll touch on all of these applications.

PERFORMANCE ENHANCEMENT COATINGSOnce viewed as unnecessary “add ons” and initially thought of by some builders as “gimmicks,”specialized internal engine coatings have proven their worth in terms of both power increases,friction reducers and benefits in terms of engine longevity. Today’s coatings include those designedto reduce friction and enhance lubricity, thermal barrier coatings for increased engine efficiencyand protection of components exposed to extreme heat levels, and drainback coatings that speed-up oil return to the sump.Today's available coatings offer distinct advantages with regard tothermal control, increased lubricity and resulting reduction of friction, as well as oil sheddingproperties that serve to free-up horsepower by reducing parasitic oil drag on rotating assemblies.In a nutshell, four distinct types of coatings are available for performance engine applications:thermal barrier coatings, heat-emitter coatings, low-friction coatings and oil-shedding coatings.

THERMAL BARRIER COATINGSThermal barrier coatings (which can be referred to as a heat shield) feature a ceramic formulation,designed to prevent excess heat from passing into and being absorbed into a component.Applications include piston domes, turbocharger housings, cylinder head combustion chambers,exhaust ports, exhaust valve throats and exhaust manifolds and tubular headers.

The specific formulas will differ depending on the application. Specialized thermal barriercoatings applied to piston tops aid in reflecting heat, reducing the amount of piston expansion(allowing the builder to maintain more consistent wall clearance) and protecting the piston fromextreme temperatures encountered in forced induction systems. For forced induction and nitrousapplications, highly specialized thermal barrier coatings are available to not only enhancecombustion efficiency but to protect the piston from potential heat-related damage. By applying aceramic heat shield coating to areas exposed to the combustion process (chambers, valve faces,

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exhaust valve throats, exhaust ports,piston tops and the exhaust path),combustion efficiency can be enhanced,which aids in producing additional power.Essentially, thermal barrier coatingsapplied to the combustion and exhaustpath serve to contain combustion heatenergy, greatly reducing heat soak andresulting wasted thermal energy.

Bear in mind that the quality ofapplication of a ceramic coating (especiallyfor internal engine components) isextremely critical. The last thing you wantis for hard and potentially damagingceramic to break loose and contaminatethe engine. That’s why you need to useestablished coating services such as thoselisted in this article. When properlyapplied, the coating not only adheres tothe applied surfaces, but permanentlybonds to the material, essentiallybecoming part of the base material. Ifsubstandard application practices are used,the coating may not be fully bonded and

20 JULY-SEPT 2014 engine professional

ENGINE COATINGSBY MIKE MAVRIGIAN

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MAHLE Clevite, as an example, uses a polymer-based moly-graphite coating on their performancebearings. Specific formulas may vary but the goal is the same: to promote oil retention and to provide aprotective lubricity surface in the event of inadequate or temporary reduction of oil delivery, such asduring a cold start or temporary starvation.

EPQ314 18-37_Layout 1 7/26/14 10:49 AM 0



could flake off. In other words, don’t trythis at home. In the course of buildingengines for 24-hour endurance racing, I’vehad many dozens of engine buildcomponents ceramic coated (heads,pistons, valves, exhaust) with absolutesuccess, but I’ve seen a few devastatingissues with components that were“coated” by inexperienced mom ‘n popshops that caused serious damage. Don’tbe afraid of ceramic internalcoatings….the top shops do anoutstanding job, and they know whatthey’re doing. Their specific processes arekept highly confidential (they could tellyou how it’s done, but then they’d have tokill you). Don’t be tempted to cheap-outand go for bargain basement services. Ifsurface prep, temperature and applicationisn’t right, you’re asking for problems.While I admit that I haven’t used all of theshops listed in this article, but I have usedthe services of Swain and Polydyn, andhave never had a problem. After

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Specialized wrist pin coatingssuch as the Casidium treatment

shown here increases pin lubricity.

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EPQ314 18-37_Layout 1 7/26/14 10:49 AM Page 22


experiencing my initial results years ago with twoendurance engines where I took advantage ofthermal barrier, anti-friction and oil sheddingcoatings, I became an avid fan of the processes, asour engines produced measurable increases in powerand significant resistance to wear.

Ceramic top coatings on pistons serve as a thermal barrier,reducing heat soak and protecting the piston from extremesof heat. Anti-friction (usually moly) skirt coatings providesuperior oil retention and provide a slick surface to reduceskirt-to-wall contact wear.

In addition to piston dome coating, the same high-temperatureheat barrier coating can be applied to the combustionchamber, all valve faces, exhaust valve throats and exhaustvalve ports, which completely encapsulates the combustionstream path (courtesy Dart).

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ANTI-FRICTION, OIL MANAGEMENT AND HEAT-RELEASE COATINGSAnti-friction coatings are applicable tosurfaces that make, or potentially makecontact, such as (but not exclusive to)main bearings, rod bearing, cam bearingsand piston skirts. Anti-friction coatings,also called lubricity coatings, provide atemporary lubricity when/if the surface isstarved for oil, upon cold-starts, etc., butalso serve to retain oil on the surface.While specific anti-friction coatingformulas vary among the coating services,the materials are generally composed ofmoly, graphite or Teflon based materials.The intent is to provide better oil retentionand to provide a super-slippery surface.Piston skirt coatings are generally appliedat an average thickness of about .0005"per side, which might provide about a.001" increase in piston overall skirtdiameter. Since the moly is applied in sucha thin layer, no additional bore dimensionchanges are required to run “moly-coated”pistons. Unless otherwise instructed by the

piston maker, DO NOT compensate forthe added moly coating when finishingyour bores.

In addition to anti-friction coatings,specialized materials called “oil shedding”coatings treat metal surfaces to repel oil, inorder to reduce parasitic energy losses thatwould normally be caused by oil cling.Applications include crankshaftcounterweights, connecting rods. Inaddition to reducing parasitic drag, thesecoatings (also referred to as “oildrainback” coatings) can be applied tospecific surfaces to prevent oil cling and tospeed-up oil return to the sump, such asthe inside of valve covers, oil pan walls,windage trays and even oil pumps.Applying an oil-shedding coating to theflow areas of the pump (gears andpassages) allows the pump to moreefficiently move oil, reducing the amountof oil that clings to the passage surfaceareas. Think of it as an aerodynamic bodyeffects approach that reduces the dragcoefficient for the oil pump.....an oil

shedding coating lets oil move through thepump faster while reducing the amount ofoil that "hangs around" by sticking topassage walls.

Valve covers represent a uniqueopportunity to help control temperaturesthat would otherwise encase the valvetrain,in addition to promoting quicker oildrainback inside the covers. A thermalbarrier coating can be applied to the coverexterior, while an oil shedding coating canbe applied to the interior. This dualcoating combination helps to reduceradiated cover temperature, whilepreventing oil from clinging to the coverroof and walls, allowing oil to scoot backto the moving parts where it's needed.

Heat emitter coatings represent yetanother specially-formulated applicationthat, unlike a ceramic barrier coating thatprevents heat transfer, serve to promotethe release of heat. This type of coatingcan provide a distinct longevity advantageto components such as valve springs,which serves to prolong spring life.

This sample array of parts helps to illustrate heat barrier and anti-friction coating applications. The examples shown here, courtesy of Swain, include high-temperature thermal barrier coatings on head chambers, piston domes, turbo housing and headers; anti-friction coatings on skirts,

valve stems and bearings; and heat-release (shedding) coatings on valve springs.



DIAMETER / CLEARANCE INCREASESIn addition to providing power enhancement andlubricity improvements, specialized coatings (or otherspecialized processes) are sometimes available toincrease the surface diameter of a part, or to restore aworn part. Using an appropriate process, a skilledcoater may be able to build up piston skirt diameters,restore cam journal dimensions, etc. Services andspecific applications vary, so check with the coatingshop of your choice. Keep this in mind as a potentialanswer to a specific dimensional or clearance issue.

Ceramic coating of exhaust manifolds or tubular headers act as aheat barrier, reducing exterior surface temperature (and heatradiation inside the engine bay) and promote a more efficientexhaust flow, in addition to the obvious corrosion prevention(courtesy Cerakote).

Camshaft bearings are readily available already coated with molyfrom several bearing makers. Or, you can send your bearings outfor coating.

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POWDER COATING, ANODIZING ANDHYDROGRAPHICS

POWDER COATINGThe process of powder coating is muchmore simple than most folks realize. Thissimply involves applying dry “thermoset”or “thermoplastic” paint powder,followed by oven-curing, which melts andflows the dry powder, resulting in atough, protective finish.

Typical powder coat applicationinvolves spraying the powder in a state ofelectrostatic charge. The coated part isthen heated to approximately 320 - 410degrees F (typically around 395 degreesF), which causes the powder to melt andflow, creating a continuous film coating.Once cured, powder coating provides avery durable protective finish that ishighly resistant to chipping, peeling orcracking and weather/road conditionexposure. Types of powder vary in termsof resistance to heat, but powders are

offered that will withstand as much as100 degrees F without discoloring. Forautomotive use, a thermoset type powderis used to better withstand heatenvironments.

The application is fairlystraightforward. The part to be coated

must be clean and must provide a decent“tooth” for paint adhesion. Typically thiswill involve blasting the surface withaluminum oxide or other media (butavoid silicon glass bead, as this cancontaminate the surface). The part is thenwashed and dried.

An oil shedding / oil drainbackcoating applied to the inside of oilpans promotes faster oil return to

the sump. (courtesy Calico)



Powder spraying is done with an electrostaticspray gun (or in a powder-emitting tunnel), while thepart to be sprayed is grounded. Because the powderparticles are electrostatically charged, the powderwraps around the part, covering all surfaces. Thepowder will remain on the surface as long as theelectrostatic charge is present (if the part is bumpedduring transport into the curing oven, the powder canfall off). Once the powder paint has been applied, thepart is carefully moved into a curing oven, where it’sbaked at 360-400 degrees F to as high as 550 degreesF (depending on the specific application and type ofpowder). Note: It is preferable to pre-heat the partprior to paint, which serves to cook off any surfaceoils, fingerprints, etc. When the part is pre-warmed inthis manner, the powder paint adheres better,especially to small nooks and crannies.

While some powder coating shops may offer onlya limited color selection, powders are actuallyavailable in an incredible array of colors and finishes,including flat matte, semigloss, satin, high gloss,pebble finish, “hammered” textures, wrinkle finishand more. Even metallic chrome-like, neon and

Anodizing alloy parts involves an oxidation process as opposed toa coating process. For the sake of appearance, color dyes areadded to provide the color(s) of choice. Anodizing protects thesurfaces from further oxidation. Hard anodizing (depending on theapplication) is also available to provide a harder, more densesurface.

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translucent finishes are available. Youmay need to search a bit for a shopbeyond your immediate locale for certaincolors and/or textures, but it’s allavailable.

Regarding powder-coat resistance toglycol brake fluid, brake fluid won’tblister or remove the powder coat, but ifleft exposed for a long enough period oftime, exposure to brake fluid can create astain or dull sheen, or at worse, thepowder coat can turn “muddy” andpliable. So, even though a piece has beenpowder coated, you need to continue tobe careful to avoid glycol brake fluidexposure.

ANODIZINGIt’s important to understand thatanodizing is not a coating, and hasnothing in common with coatings such aspaint, powdercoat or plating. Anodizinginvolves an electrolytic oxidation processthat alters the surface of an alloy

component, with the primary benefitinvolving surface protection, and a degreeof wear-resistant surface hardening. Theaddition of a dye provides the desiredcolor, which is absorbed into the oxidizedsurface. Aluminum materials may beanodized clear or in any of a variety ofcolors. Aluminum material may beanodized in a variety of colors, including“clear.”

During the process, aluminum oxide isgenerated during anodizing at/near thesurface, creating aluminum hydrate,which provides the additional surfacehardness. Since the anodized surface isalso fairly porous, it readily accepts acolor dye. In terms of increasing surfacehardness, varying levels of hardness arepossible, depending on the component’sapplication.

The treatment is referred to asanodizing because the part being treatedforms the anode of an electrical circuit.The process alters the microscopic texture

of the alloy surface and the crystallinestructure of the aluminum surface.

The anodizing process applies toalloys only. Anodizing steel or ironmaterials will result in unappealingoxidation. While the process can beapplied to aluminum castings, results maybe sketchy due to irregularities orimpurities in cast materials, as a dull grayor non-uniformity color may result. Thebest choices for anodizing are aluminumbillet/machined/forged materials.

The appeal of the anodizing processinvolves avoiding surface corrosion, toapply a color to the surface, anddepending on the level of anodizing, toincrease surface hardness. The finalanodized part’s surface will readily allowthe surface finish to be revealed. By this, Imean that you can consider clear or coloranodizing as an almost translucent finish.If you want high gloss, the part must bepolished prior to anodizing, or a “brightdip” treatment following anodizing. If

Custom color anodizing is available from a select number of shops. These exhaust port plates were custom anodized in a violet color. Since anodizing, especiallyfor a part that was previously anodized in a different color, results in a dull, matte finish. If gloss is desired, the part must be polished after stripping, or “brightdipped” by the shop after color anodizing.


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you want a satin or semigloss finish, thepart can be buffed with a light abrasive(such as Scotchbrite) prior to anodizing.If you want a matte finish, don’t performany polishing or buffing.

Common applications for color-dyedanodizing include aluminum pulleys,carburetor spacers, brackets, –AN hoseand fittings, spark plug wire dividers,miscellaneous spacers, boost pressureregulators and wastegates, etc. As longas the component is made of a machinedor formed aluminum alloy, it can beanodized. As noted earlier, castings maybe anodized, but appearance results willvary depending on the makeup of thecasting.

Another potential issue to be aware ofis material uniformity. If you plan to havepieces color anodized, all componentsmust be made from the same materialstock. Variances in the alloy mix can (andusually do) result in color variances. Forexample, if you fabricate a handful ofitems from a variety of aluminum stock(sheet, round or square tubing, etc.),


Anodizing protects the alloy surface from oxidation and corrosion. The color dye is added simply for thesake of appearance.



differences in the alloy formula can easilyresult in varying shades of the desiredcolor. If you opt to fabricate items fromaluminum stock, all pieces should bemade from the same stock (preferablywith all pieces cut/machined from a singlepiece of stock). If you grab miscellaneouspieces of aluminum from your inventoryor from a local scrap metal supplierwithout paying attention to the alloycontent and/or grade of aluminum, evenwhen the batch of items is anodized atthe same time using the same color dye,you may very well end up with mis-matched colors. For instance, if all piecesare to be anodized in a blue color, if thegrades of aluminum differ, some piecesmay be darker or lighter than others. Beaware of this potential concern. Ifdissimilar alloy materials will be in closeproximity to each other when installed,be aware that the colors may notperfectly match!

You may have noticed when buyingcolor-anodized –AN hardware that evenfrom the same manufacturer, blues or


Powder coating involves spraying adry paint powder onto anelectrostatic-charged component,followed by heat curing in aspecialized oven. The static chargedraws the powder to the surfaceduring application.


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reds may not be consistent. This is likelybecause the pieces may have beenmachined from a variety of billet stock.While integrity and durability isn’tcompromised, the final color hues mayvary.

HYDROGRAPHICSThis process is strictly cosmetic andserves no mechanical or thermal function.Also referred to as “wet-dip,” “ink filmtransfer,” or “ink transfer printing,” thisprocess involves the application of agraphic ink film that “wraps” onto asurface to provide a desired appearance.Relative to engine builds, applications caninclude valve covers, timing covers, oilpans, intake manifolds and variousbrackets. Literally thousands of filmgraphics are available, including thosethat provide the appearance ofcamouflage (in various colors/designs),blue backgrounds with water droplets,skulls, barbed wire, carbon fiber, machineturnings, diamondplate metal, variouswoodgrains, and more. If you can


Hydrographic films are available in a dizzying array of designs. The intake manifold shown here wastreated with a “carbon fiber” film. Hydrographics, or “wet film printing” provides only an appearancebenefit. A high-temprature clearcoat protects and seals the ink film.


ENGINE COATING SOURCES/SERVICES(Examples)

*NOTE: MAHLE Clevite and Federal-Mogul offer specific parts with coatings already applied, butdo not offer general coating services to the public.

ALSO NOTE: Some crankshaft and connecting rod makers now offer optional oil-sheddingcoatings for their respective products.

EXAMPLES OF ANODIZING SOURCES(Refer to your local phone directory, or perform a Google-search for anodizing shops in yourregion. Listed below are three sample anodizing shops that I’ve used in the past with greatresults.)

POWDER COATING AND HYDROGRAPHICSThese services are available nationwide, usually with shops in close proximity to all cities andtowns. Check your local directories or Google to find a shop in your area. You shouldn’t have anytrouble finding a good powder coater nearby, but finding a good hydrographic (wet dip/inktransfer) shop may present more of a challenge. If you have trouble finding a wet dip shop,check with your local gun and/or archery stores, since wet dip camouflage treatments arecommon for applications such as shotguns, bows, etc. A competent wet dip shop should haveaccess to a wide variety of ink films, such as carbon fiber, diamondplate, etc.



imagine it, the graphic film probablyexists.

In basic terms, the graphic isapplied as follows: the part to betreated is cleaned and primed, thenpainted with an appropriate basecolor (since most films aresomewhat translucent, the basecolor will influence the finalappearance). For example, if youwant a pair of valve covers done in“orange” carbon fiber, an orangebasecoat is applied. If you want atraditional carbon fiber look, ablack basecoat is applied. Thegraphic ink film is then laid on awater surface (in a temperature-regulated tank designed for theprocess). Water begins to breakdown the binders in the film, and anactivator is then sprayed onto thefloating film to fully break down thebinders, to leave a floating “oilslick” of the graphic. The part isthen carefully dipped through thefilm, with the film clinging to thepart’s surfaces. Any film that hasnowhere to attach floats loosely andis shaken off. There is a skillinvolved here…it’s not as simple asdipping an Easter egg. Once the partis removed from the water, it isdried and then clearcoated toprotect the film. For parts that willexperience heat, such as intakemanifolds, valve covers, etc., aspecial high-temp urethane clearcoatis applied.

Again, a wet dip treatment isstrictly for the sake of looks, whereyou desire a certain custom graphicappearance.�

Mike Mavrigian has written thousands oftechnical articles over the past 30 yearsfor a variety of automotive publications.In addition, Mike has written many booksfor HP Books. Contact him at BirchwoodAutomotive Group, Creston, OH. Call (330) 435-6347 or e-mail:[email protected]: www.birchwoodautomotive.com

CALICO COATINGSP.O. Box 901Denver, NC 28037888-236-6079www.calicocoatings.com

CERAKOTE CERAMICCOATINGS7050 6th St.White City, OR 97503866-774-7628www.cerakotehightemp.com

DART MACHINERY353 Oliver St.Troy, MI 48084248-362-1188www.dartheads.com

DIAMOND PISTONS23003 Diamond Dr.Clinton Twp, MI 48035877-552-2112www.diamondracing.net

FEDERAL-MOGUL/SEALED POWER*26555 Northwestern HwySouthfield, MI 48033800-325-8885www.federal-mogul.com

JE PISTONS8 MasonIrvine, CA 92618714-895-9594www.jepistons.com

MAHLE CLEVITE INC.*1350 Eisenhower PlaceAnn Arbor, MI 48108-3282800-338-8786www.mahleclevite.com

POLYDYN (Polymer Dynamics)11211 Neeshaw Dr.Houston, TX 77065888-765-9396www.polydyn.com

SWAIN TECH COATINGSP.O. Box 33Scottsville, NY 14546585-889-2786www.swaintech.com

TECH LINE COATINGS, INC.26844 Adams Ave.Murrieta, CA 92562972-775-6130www.techlinecoatings.com

WISECO PISTONS7201 Industrial Park Blvd.Mentor, OH 44060-5396800-321-1364www.wiseco.com

McNICHOLS POLISHING & ANODIZING12139 WoodbineRedford, MI 48239313-538-3470

METFIN4th St. at RailroadNorth Wales, PA 19454215-699-3505

FORT WAYNE ANODIZING2535 Wayne TraceFort Wayne, IN 46803260-424-1030


eliminator - engine coatings · 2018. 10. 23. · 22 july-sept 2014 engine professional engine...

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