The JE Pistons have very aggressively deep valve reliefs cut into the domes to allow for the use of a very high lift fast velocity roller cam. The lustrous coloring is a result of the WPC treatment. WPC reduces skirt friction and improves the life of the ring lands and pin bores. Our JE pistons are forged from tough low silicon 2618 alloy, best suited for turbo and racing engines.
Since our engine is boosted the top ring land is moved downward for strength. This means that the ring package has to be compressed to be shorter. Note that the oil ring bridges the piston pin bore due to the stroke and long rod. Although some frown upon having an unsupported span of oil ring we have never had problems with wear or oil consumption and several racing engines that we have done this too. The top ring is gas ported for better seal and there is a pressure equalization groove between the two compression rings. The oil ring groove feature dual piston pin oiling holes to provide the pin and the rod small end with lots of oil, important on a dry sump engine that tends not to have much windage.
Since turbo engines typically have more side load on the piston skirts, we elected not to use JE’s excellent slipper skirt or asymmetrical skirt design. Instead we opted to go for a good old fashion full skirt design for maximum support and to minimize bore rock.
JE’s forging blank for the Small Block Chevy has an excellent near net shape so our piston can be light without resorting to expensive undercrown milling operations.
Our piston pins are taper wall H11 tool steel but unlike an NA engine’s super light thin wall construction our pins are really thick in the center. The load of a turbo engine can flex the pin causing it to stick in the small end bushing. When this happens the result is a pin that spins out of the rod so you need a beefy piston pin.
Our JE Pro Seal rings are thin low tension 1.1mm compression rings, the top ring being chrome with the second ring being ductile iron with a napier profile for reduced oil consumption. The oil ring is a conventional thin rail type to help keep our ring package compact in our limited space.