Page 6 of JE Pro Seal Catalog by JE Pistons

7 RING FUNCTIONS VERTICAL GAS PORTS FIGURE 7 FIGURE 8 LATERAL GAS PORTS RING ROTATION Ring rotation is critical for the distribution of heat to lower temperature sections of the piston and the cylinder wall. If the rings were stationary in the ring groove, the piston and cylinder wall would experience excessive heat in localized areas. This condition can cause scuffing of the cylinder wall, premature wear, piston to ring microwelding and possibly ring butting. The rate at which the ring rotates is determined by the piston rods, friction between the ring sides, bore finish, and cross hatch angle. TOP RINGS CONTINUED GAS PORTING Combustion pressure can be directed behind the top ring with the addition of vertical or lateral gas ports on the piston. Vertical gas ports are small holes drilled into the top (or deck side) of the piston that lead to the back of the top ring groove. These holes allow combustion pressure to enter the top ring groove directly behind the ring on the combustion stroke forcing the ring face against the cylinder wall for maximum seal (fig. 7). Lateral gas ports perform the same function by providing a pathway for the combustion pressure to enter the ring groove with less interference (fig. 8). Gas ports are extremely beneficial when using reduced radial width and low tension top rings. They aid in ring seal on the combustion stroke while reducing friction and drag on the remaining strokes that can rob the engine of horsepower. As a general rule, vertical gas ports are mainly used in drag race applications while lateral gas ports are used for circle track and endurance racing (vertical gas ports tend to plug with carbon more than lateral gas ports and are usually application specific). Ring Rotation A coarse pattern will cause fast ring rotation A fine pattern will cause slow ring rotation Side View PISTON RING SURFACE PISTON RING LAND SURFACE MICROSCOPIC PEAKS ON SURFACES GAS AND OIL HIGH AREA ATTACHED TO RING SCALE OF HIGH AREA ON SURFACE IS MICRO INCHES Piston Ring Piston Ring Groove WHAT IS MICROWELDING? Micro-welding occurs when piston material from the ring groove transfers onto the axial side surface of the ring itself. As a result, ring rotation begins to deteriorate followed by increased blow-by due to the ring losing bore conformity and torsional twist. As material transfer continues, axial clearance disappears and the ring will eventually become lodged in place, having welded itself to the groove. Micro-welding is typically seen only on top rings and is most common where the axial clearance between the ring and its groove become too tight for the conditions or application. In order to help alleviate this problem, JE offers our exclusive Ultra Groove machining process to vastly reduce the microscopic waves and bumps left by conventional machining methods. To further improve ring groove quality, JE offers hard anodizing of the piston top ring groove, which creates a very hard, durable contact surface. When combined with our UFR or CFR rings, axial clearances can be greatly reduced while also significantly reducing the possibility of micro-welding.

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