NPR SWF30031-2 Piston Ring Set 0.50mm Oversize

The NPR SWF30031-2 is an oversize piston ring set manufactured by NPR of America (Nippon Piston Ring), designed for Subaru engines requiring a 0.50mm overbore specification. NPR is a globally recognized OEM and aftermarket supplier of precision engine components, and these rings are engineered to restore cylinder sealing, compression, and oil control in worn or freshly rebuilt engines.

Key Features:

• OEM-Level Quality: NPR supplies piston rings directly to major Japanese automotive manufacturers, ensuring OEM-equivalent fit and performance
• 0.50mm Oversize (0.020" Over): The "-2" suffix in NPR's part numbering system denotes a 0.50mm oversize bore specification, suitable for engines that have been bored or honed beyond the standard diameter
• Steel Ring Construction: NPR's steel ring designs provide higher tensile strength, greater fatigue life, and reduced ring wear compared to traditional cast iron alternatives
• Complete Ring Set: Includes the compression rings and oil control ring assembly required for a full cylinder rebuild
• Precision Surface Treatments: Rings feature engineered surface treatments (such as chrome or ferrox coatings) to optimize sealing against the cylinder wall and reduce break-in time
• Extended Service Life: Steel ring construction reduces ring wear, contributing to longer engine service intervals and improved oil economy

NPR piston rings are manufactured to JIS (Japanese Industrial Standards) specifications and are trusted by professional engine builders worldwide. The SWF30031-2 is the correct choice for Subaru engine rebuilds requiring an oversize bore piston ring set. Always verify the correct oversize specification against your measured bore diameter before installation.