Nobody likes paying for insurance, but when it comes time to file a claim, everyone is relieved that they have it. The same could be said about coatings. Some don’t like putting out the money for what they mistakenly believe to be a nonessential luxury. However, when something goes wrong that could have resulted in a catastrophic failure but only caused a minor inconvenience, they’re happy that they had the foresight to pay for coatings. For those of you who don’t know what coatings are for, their use can be summed up in one word: PROTECTION.
If you look at coatings in their raw form, all you’ll see is powder. BUT, it’s a powder with a lot of technology behind it. Have you ever thought that a powder would act as a film of oil, in case of an oil pump failure? It does, and it might just be that coating that keeps your rods from hanging out the side of your block. Then there is the biggest factor for most – heat. Keeping combustion temperatures down while keeping the engine bay cooler can be achieved by using some “simple” powders.
“We started using coatings back in NHRA Pro Stock about fifteen years ago in order to gain horsepower,” explained Dart founder Dick Maskin. “What we found is that not only did we gain horsepower, but we also gained added protection.” Coatings help protect everything from piston tops to the inside of oil pans. As the old saying goes, ‘An ounce of prevention is worth a pound of cure.’
“You know, I have spun cam bearings and I also know people who have, and that will just ruin your day,” Maskin said. “This is why we coat all the cam bearings in the blocks we sell, and to our knowledge, we have never heard of one fail.” Great advice from the master, but let’s dig a little deeper.
Why Coat – And What Can You Coat?
There are coatings for virtually every part of an internal combustion engine, which do everything from shedding oil to retaining heat. Even parts like crankshaft counterweights can be coated with an oil shedding coating, to keep the weight of the oil off the rotating assembly.
Water jackets can be coated to prevent corrosion, especially important in marine applications, and lubricating coatings can be used to promote air flow on hard to port items.
We are going to go over some of the popular coatings that Dart Heads offers from their coating department.
The coating department at Dart's headquarters in Troy, MI.
Anyone who has ever owned an iron block knows how they look after a short time, and it isn’t much better on the inside. If you have ever had an oil pump fail, you’ve most likely had to deal with spun bearings. Being smart with your money when it comes to coatings can help combat these horrific situations.
Coatings are typically powders made from different compounds, that are sprayed evenly over the part through a low pressure airbrush. After the coating has been applied, it is allowed to air dry.
This not the final step, however, as the coating does not properly cure until it is baked in an oven for up to an hour. During this process, the coating becomes chemically bonded, virtually becoming part of the metal itself.
Coatings are designed to block heat, reduce friction, shed oil, and reduce corrosion. In order to truly understand why a coating is needed, you need to understand the three main properties you are trying to combat: Friction, Heat, and Corrosion.
There are multiple factors to consider when it comes to coating a part, the first being friction. The concept is rather simple – if you can reduce the friction of a moving part, less energy is required to move it, thereby freeing up lost power. The two most common places you are probably thinking of are your piston skirts and main bearings. A Teflon based coating will act as a permanent layer of oil that will provide protection in case of oil starvation.
DCB-3 Coated cam bearings (center) offer lubrication in case of oil loss. All Dart engines come with coated cam bearings pre-installed.
Turbo compressor housing coated with DC-4 to increase airflow and decrease turbulence.
There are numerous places aside from the inside of an engine where coatings can be beneficial. The inside of a turbo compressor housing can be coated to decrease turbulence and increase airflow. The interior of a smooth plenum can hurt fuel atomization, and adding a slight texture coating can actually promote a healthier air/fuel mixture.
The last application in this line is an oil shedding coating for parts that do not need oil on them, such as rods and crankshaft counterweights. Using a coating in these instances will decrease weight on the rotating assembly.
This is the second most obvious factor of an engine, the heat generated through combustion. Not only does reducing heat increase power, it also increases life. Combustion chamber components, such as piston tops and cylinder head bowls, can benefit greatly from a heat reflective coating that will keep the heat in the combustion chamber and off the parts. This promotes a better burn, while decreasing metal fatigue. A heat reflective coating can even be used on external engine parts that you don’t want to get hot, like the outside of an intake manifold.
Turbo manifold coated with DC2 to keep heat in.
Piston tops coated with DC2 heat reflective coating. The skirt is coated with an MOS2 Teflon coating to promote lubrication.
Coatings designed to retain heat will also help keep engine bays cooler. Headers and turbo exhaust housings are prime examples of engine parts that emit excessive heat. Keeping the heat in the exhaust keeps the engine running cooler.
“Alcohol and methanol engines face special challenges when it comes to corrosion,” explained Nate McInnis of Dart. “Coatings using a blend of fluorinated polymers are often used to address the harsh effects of these fuels on piston skirts, bearings, and on valve springs. As with the thermal coatings above, many of these are formulated to provide frictional benefits as well, making them doubly useful.”
During our visit to Dart, we were able see that top fuel teams use this same coating on the inside of their fuel pumps and pump gears to reduce the corrosion that is also caused by Nitromethane.
Funny Car pump cases and gears coated with DC-7 to resist corrosion from Nitromethane and other gases.
This common corrosion application can also be used on marine applications. Salt water can wreak havoc on the outside of iron blocks (and even aluminum), and on the inside where boats use the ocean water to cool the engine. Water passages in the intake manifold, cylinder heads and block can all be coated, and can serve as a thermal barrier from surrounding components and keep coolant cooler.
On a Budget? What Dart Recommends First
While you can go crazy coating every conceivable part of an engine, it might not be the most economical option. Start out with the parts that are most accessible first. If you are building a new engine, that would be the time to get any internal parts coated. Dart can even coat used race parts if you are freshening up an engine.
DC2 heat reflective barriers on intake manifolds keep heat out.
While at Dart, we asked Richard Maskin what he would recommend as the first three coatings for someone building an engine. This is what he had to say:
Cam Bearings – For oil protection. This is the number one part in the engine that is likely to not get oil early. Spinning a cam bearing can not only destroy a cam, but the block itself.
Rod/Main Bearings – Again, for oil protection. The thin layer will provide lubrication if oil starvation occurs. Main bearings can cause irreparable damage to the bottom end, while a rod bearing can cause a rod to break and send pieces through your block.
Piston Skirts – Also for oil protection. The piston skirt can become hot from friction if oil is starved from the cylinder walls, causing piston cracking and possible total engine failure.
Turbo exhaust housing coated with DC2 to keep heat in.
Dart’s Different Library:
DCI MOS2 Teﬂon Skirt Coating – Reduce Friction
Prevent piston skirt scufﬁng and galling, extending piston ring seal life with
a DCI MOS2/Teﬂon skirt coating.
DC2 High Temperature Reﬂective Heat Barrier – Protect and Enhance
Protect piston tops with DC2, high temperature highly reﬂective heat barrier. Enhances ﬂame propagation, reﬂects more heat into the combustion chamber, protecting piston tops, piston rings and lands.
Ideal for any high temperature – heat reﬂective / insulative application like combustion chambers, valve faces, exhaust port, intake manifold, brake caliper/pad/piston.
DCB-3 Engine Bearing Coating
Dart’s engine bearing coating is a Molybdenum disulﬁde / Teﬂon based material with high-load / non-stick properties, providing protection to bearings and crankshaft in case of lack of lubricant or detonation.
The bowls of the heads are coated with DC2 heat reflective coating, while water jackets are coated with an anti-corrosive coating.
DC-4 Lubricating Coating
High pressure lubricant contains a combination of lubricating pigments, including MOS2, creating exceptional wear life and load capacity in applications such as valve springs, oil pump gears, ring and pinion, transmission gear and bushing, valve stems, timing gears, bearing races, camshafts and any friction related area.
DC-5 Oil Shedding Coating
Oil shedding coating for applications in which oil and other petroleum liquids should be shed off rather than retained on a particular piece, such as crankshaft counterweights, inside oil pan, windage trays, inside valve covers and connecting rods.
DC-6 Anti-Friction Coating
Special coating for alcohol / methanol engines. Primary uses are piston skirts, bearings and valve springs. Fluorinated polymers have a low coefﬁcient of friction and are chemically inert. Lubricates without shedding.
DC-7 Anti-Corrosive Protectant
Anti-corrosive protectant coating for application in an environment of exposure to weather elements, gasoline, alcohol, Nitromethane, brake ﬂuid, and antifreeze on varied types of materials, including magnesium and aluminum.
Iron cylinder head coated with DC-7 anti-corrosive coating to keep from rusting.
Again, Insurance For Your Engine!
While choosing a coating can seem like a complicated task because their uses vary so widely, and they have long names that are difficult to pronounce, the main thing to remember is that coatings offer protection for your expensive engine parts.
Even if you don’t have brand new parts, you can still increase their effectiveness and extend their lifespan by using coatings. If you’re still confused about what coatings are best suited for your needs, call Dart. Let them know what your specific application will be used for. They will be happy to offer their advice and suggestions, and you’ll be able to rest a bit more easily knowing that you have insurance for your engine.