An Introduction to Swain Tech’s Two Stroke Performance Coatings
High performance does not come without its price. That price often is reduced reliability in the form of damaged internal engine parts. However, high tech, high performance engine coatings can now improve performance and reliability. Best of all, there are no trade-offs, no downside to the benefits coatings provide. It’s a win-win situation.
Heat is necessary for power; engines operate by converting thermal (heat) energy into kinetic (movement) energy. But, heat also takes its toll on metal, often melting lightweight parts like aluminum or alloy pistons. For these reasons pistons were traditionally the weak link in the drive train. That doesn’t have to be the case today. Lightweight aluminum and alloy pistons can be coated with thermal barrier and friction reduction coatings to ward off the reliability nemesis called heat.
A .002” ceramic thermal barrier coating (TBC) protects piston domes. TBC™ holds heat inside the combustion chamber where it can power the sled, rather than dissipate through the piston to weaken or burn the metal. TBC also protects parts from high temperature oxidation and reduces heat transfer by spreading the heat over the entire coated surface. This encourages proper flame travel and eliminates hot spots. Less heat conduction through the wrist pins and rods keeps the crank and bearings cooler, too. And, the coating is thin enough that no clearance provisions have to be made.
Friction between the piston skirt and cylinder wall is reduced with a tungsten-molybdenum disulfide polymer matrix coating. This material, which we call PC-9™, has an extremely low coefficient of friction. Applied .0008” thick to piston skirts, the durable coating reduces scuffing and friction caused by piston movement.
Standard aluminum pistons can expand too much when subjected to high heat, and this expansion can cause them to seize. This does not happen with coated pistons because the thermal barrier coating reduces heat transfer. As an added benefit, carburetor jetting can be safely leaned down to achieve better performance.
Pistons coated by Swain Tech Coatings can usually be identified by their white domes and dark gray skirts. TBC Thermal Barrier Coating is white and PC-9 friction reducing coating is dark gray. However, Swain Tech StealthCoat™ has the same color and texture as piston metal. StealthCoat is for racing classes in which stock appearing parts are required. And, GoldCoat™, a special .003” thick Swain Tech thermal barrier coating for nitrous and turbo charged engines, is gold in color.
The energy that creates horsepower comes from the heat of combustion. Adding nitrous oxide to the fuel/air mix greatly increases the intensity of the energy-generating heat in a combustion chamber. When that heat reaches certain intensity, it can melt pistons and other engine parts. GoldCoat protects pistons from heat damage, actually extending engine life while boosting power.
Pistons are the most popular coated parts. However, high tech coating of other snowmobile parts will increase power and reliability even more. TBC applied to heads, enables the engine to convert more heat to power. Coating the entire combustion chamber surface area (piston top and head recessed chamber) improves combustion efficiency, resulting in higher horsepower. A Black Body Emitter (BBE) heat radiating coating applied to the outside of the cylinder and head, will help dissipate any heat that does get through the TBC and is particularly effective on hot-running fan cooled engines.
Exhaust systems, coated with White Lightning, keep exhaust gases hotter longer, improving the scavenging effect. White Lightning is a unique exhaust system coating. The white, .015” thick, three layer thermal barrier coating keeps heat inside the pipe, which increases exhaust gas velocity for more efficient heat extraction. A good looking, rust free exhaust system, coated with White Lightning, also contributes to an increase in horsepower – as much as three percent.
White Lightning is unequaled; it is a true, permanent ceramic thermal barrier, not a hi-temp paint like other shiny coatings. It can be used for trail riding, drag racing, oval track and cross country sleds. The coating reduces under-cowl temperatures, increases gas velocity and makes turbo charger systems perform better. The coating can also be painted without affecting its thermal properties.
Many snowmobile performance engine builders offer Swain coatings as standard or as recommended options. Do-it-yourself engine builders can have their parts coated as well. Pistons are sent to Swain’s the factory, coated and returned, usually within a week.
Engine coatings are low cost insurance in anybody’s book. A failed racing engine can be costly and eliminate you from the race. An engine that fails on a trail ride can result in a long walk back to civilization. Advanced coatings are extremely beneficial in the snowmobiler’s quest for more power, speed and reliability.