JE Pistons Ring Sets 1.2 / 1.2 / 2.5 Subaru EJ257 Block w/EJ20 Head

This is a JE Pistons ring set, part number JG4904-3937, specifically for a Subaru EJ257 block that uses an EJ20 head. These rings are crucial for sealing the combustion chamber, which directly impacts how much power your engine can make. When you're rebuilding an engine like this, getting the right ring set is key to ensuring proper compression and preventing blow-by.

This particular set features a 0.0472-inch carbon steel nitride top ring, designed for good sealing and durability. The second ring is also 0.0472 inches and made of iron phosphate. For the oil control, it includes a 0.0984-inch low-tension carbon steel chrome oil ring. These materials and dimensions are chosen to work together to manage oil, maintain seal, and reduce friction for improved performance and engine longevity. The file-fit design means you'll need to gap the rings yourself to match your specific cylinder bore, a common practice for performance builds to achieve the best possible seal.

Keep in mind that this ring set is not CARB approved and cannot be shipped to California. It's a well-built component intended for performance applications where precise engine sealing is a priority.