Wiseco 4390H Pro Tru Plasma-Moly Piston Ring Set 4.390 in. Bore

The Wiseco 4390H is a high-performance plasma-moly piston ring set designed for a 4.390-inch bore. This is a replacement ring set sized to fit a single piston, allowing builders to order the exact quantity needed for their engine build.

Wiseco offers several ring technologies across their automotive piston lineup to match varying performance and budget requirements:

• Pro Tru Plasma-Moly Ring Sets – Pre-gapped plasma-moly rings designed for cost-conscious performance builders seeking reliable sealing and durability
• NPR XX Steel Nitrided Ring Sets – Premium steel nitrided top rings and Napier-style second rings included with Wiseco Sport Compact piston kits for superior wear resistance
• 1.2mm Steel Nitride / Napier GFX Ring Sets – Used in Wiseco's late-model EFI piston lineup and select small block Chevy applications for reduced friction and improved sealing
• .043 Back-Cut Top Rings – Featured on many big block applications, the back-cut design provides extra material thickness for added strength around the intake valve area

Sold as a single-piston ring set. Order the specific quantity needed to match your engine's cylinder count. Wiseco piston rings are engineered to work in conjunction with Wiseco forged pistons and are not interchangeable with OEM ring sets in most applications.