MAHLE 3903MS-15 Piston Ring Set Bore File Fit - 3.989 1.5/1.5/3.0mm

MAHLE 3903MS-15 is a high-performance piston ring set engineered for 3.989" bore applications with a +.005" oversize specification. This file-fit ring set features metric sizing with 1.5mm top compression ring, 1.5mm second compression ring, and 3.0mm oil control ring configuration.

Ring Configuration:

• Top Ring: Ductile iron construction with plasma moly coating and barrel face profile for superior sealing and wear resistance
• Second Ring: Cast iron reverse twist design for optimal oil control and cylinder wall conformity
• Oil Ring: 3-piece standard tension design for effective lubrication management

Key Features:

• File-fit design allows precise end gap adjustment for optimal performance
• Standard tension configuration balances sealing with friction reduction
• Ultra-flat ring flanks maximize ring-to-piston groove sealing
• Advanced plasma moly coating on top ring provides exceptional durability and heat resistance
• Engineered using MAHLE's proprietary piston ring simulation software

MAHLE pioneered computer-aided ring development to minimize friction and unlock free horsepower, delivering measurable performance gains both on the dyno and at the track. This ring set represents decades of racing and OE engineering expertise.