When he developed the first ceramic piston coating more than a quarter century ago, Dan Swain’s goal was to make more horsepower. Today, coatings are in their sixth generation of development, and maintenance cost savings have emerged as one of the top objective for some engine builders and race car owners.
The engine coating has become a science that adds horsepower and longevity to engine life. To learn more about its effect on engines, we turned to two companies who have some insight on the advantages of coated engines.
Although the people we spoke with don’t race, their engines endure a bigger beating than those on the Winston Cup and other big league circuits. They are Don Vonderfecht of D&F Service and Speed in Holbrook, Nebraska, and Mike and Kristal Loescher of Finish Line Racing School in Edgewater, Florida. Vonderfecht rents Sprint engines to car owners, and the Loescher’s teach driving skills to racers, in race cars provided by the school.
Both companies were looking for ways to trim their maintenance costs, and Swain Tech Coatings was able to help with high tech engine coatings.
Inside Secrets Coated and Non Coated: The piston on the left shows what can happen to an uncoated piston (note the hole in the middle). The piston on the right has been protected with Swain Tech’s TBC™ ceramic thermal barrier coating and PC-9™ low friction/anti-wear coating on the skirt.
Inside Secrets Exhaust Port: This close up shows the Swain Tech TBC™ coated combustion chambers and exhaust ports to manage the intense heat of combustion.
Why Do It?
The theory of coating engine parts is threefold. First, the heat transfer capabilities are improved. Second, the parts and surfaces involved run with less frictional loss than uncoated surfaces. Finally, the type of coating applied provides strong surfaces that wear longer. All three facets of this process add up to a strong engine that lasts longer.
Coating a Sprint Engine
After racing Sprint Cars for 32 years, Vonderfecht and his son Dan have chosen to build coated engines. While most of their business is building custom engines for Sprint Car racers, they also have built a stable of rental engines, including 410 all-aluminum motors, NCRA 360’s and ASCS engines which can be rented for the season or by the race.
Until the winter rebuilds, D&F had only the pistons coated for its rental engines. Vonderfecht took advantage of the off-season to have aluminum heads, valves, and exhaust ports coated as well. Since using coated pistons exclusively, he and Dan have not seen a single engine failure.
How It’s Done
The piston domes are coated with Swain Tech’s Thermal Barrier Coating (called TBC™), and the piston skirts are coated with Poly Moly™. TBC™ protects the base aluminum by insulating it from intense combustion heat, which can melt or damage expensive parts. The .002” coating also holds heat in the combustion chamber, where it can be converted to horsepower. TBC protects parts from high-temperature oxidation and reduces heat transfer by spreading the heat over the entire coated surface, encouraging proper flame travel and eliminating hot spots. TBC™ works well in either gasoline or alcohol-burning engines, and allows an engine to be run leaner and with more advance, thereby increasing horsepower. Less heat conduction through the wristpins and rods keeps the crank and bearings cooler and oil temperature lower.
Swain Tech’s Poly Moly™ is tungsten, molybdenum disulfide polymer matrix with an extremely low coefficient of friction. Applied about .0007” thick to piston skirts, this soft coating partially transfers to the cylinder walls during operation to reduce scuffing and friction caused by piston movement.
Heads, valves, and exhaust ports are also coated with TBC. Coated pistons keep heat inside the combustion chamber, where the available horsepower can be extracted from it. With a coated piston, heat dissipation downward through the piston and into the bottom end will be decreased. Along with pistons, heads are often coated to keep even more heat in the combustion chamber and reduce heat transferred into the head, which leads to lower oil and coolant temperatures as they are pumped through the heads, and returning heated liquid to the block and crankcase. Valve and exhaust port coatings on either aluminum or cast-iron heads increase the longevity of these components and reduce exhaust-gas heat absorption into the heads and crisper throttle response.
Inside Secrets Head: These Brodix aluminum heads have Swain Tech’s TBC™ (Thermal Barrier Coating) applied to the combustion chambers, valve faces and exhaust ports. Results are increased power, reduced throttle “bog”, lower coolant temperatures, reduced detonation and protection from melting.
Moving southward, we took a look at the engine-coating program used by Finish Line Racing School. The school has a driving curriculum that covers open wheel and stock car-type cars. The engine used in the student environment clearly have to stand up to extremes in usage, because this kind of environment can be murder on engines.
All Finish Line Racing engines contain coated pistons, heads, valves and exhaust ports. Additionally, the engines have coated headers that are coated with a performance coating for exhaust called White Lightning™ thermal barrier coating. This three-layer ceramic coating is the best coating for keeping heat inside the exhaust system, improving scavenging and keeping the gases hot until they exit the pipe, rather than allowing them to dissipate through the metal. According to Mike Loescher, the header coating reduces engine compartment temperature by 300 degrees F. He uses an infrared gun to his students the 40-50% temperature reduction on headers. That reduction makes the driver’s cockpit bearable in Florida’s hot temperatures.
Finish Line Racing also uses some more exotic coatings to further protect their engines from the abuse that students can heap upon them. For example, oil shedding and anti-friction coatings are used on cranks, rods, valves, and bearings. Oil shedding coatings reduce power losses and heat buildup due to parasitic oil drag. Slippery coatings reduce heat and increase power reducing friction.
A typical schedule for a Finish Line race car calls for 1,000 to 1,500 laps per week. With four to five to a class, each drives about 600 laps in an open wheel modified and/or late model. Considering that many of the students have never been behind the wheel of a race car, frequent teardowns and rebuilds were required. Today, a car can go 8,000 laps easily without a teardown. The school has coated cranks, rods, and pistons that have more than 65,000 laps on them and are still useable.
Obviously, this process can deliver the secrets for engine longevity, regardless of whether you make your living racing or if racing is your weekend hobby.
When coatings were strictly for horsepower, many said it was a luxury. As engine builders and car owners realized that coatings improved engine reliability and extend the time between major rebuilding, coatings became an investment – not an expense. Today, coatings represent a maintenance investment for every racer, especially those on a budget without the resources to rebuild an engine every few weeks.