MAHLE 4145MS-15 Performance Piston Ring Set File Fit - 4.140 005 1.5/1.5/3.0mm

The MAHLE 4145MS-15 is a performance piston ring set designed for an 4.140-inch bore diameter with a +.005" file fit allowance, using a 1.5mm / 1.5mm / 3.0mm ring thickness configuration. MAHLE pioneered the use of piston ring simulation and computer development tools to engineer rings that minimize friction and deliver measurable horsepower gains — results that are evident on both the dyno and the track.

Ring Construction:

• Top Ring: Ductile iron construction with a plasma moly-coated barrel face for maximum sealing and wear resistance
• Second Ring: Cast iron reverse twist design, functioning as a check valve to relieve combustion pressure buildup and improve top ring stability
• Oil Ring: 3-piece, 3.0mm assembly for effective oil control

Key Features:

• File fit design for precise custom gap setting during engine assembly
• +.005" oversize bore fitment for use with slightly enlarged cylinder bores
• 1.5mm / 1.5mm / 3.0mm ring package — a proven performance configuration
• Ultra-flat ring flanks maximize ring-to-piston groove sealing
• Tapered Hook Groove (THG) second ring provides superior oil control and improved combustion gas management
• Low-tension design reduces parasitic drag and contributes to power output
• Backed by MAHLE's motorsports heritage and used by professional race teams worldwide

The MAHLE 4145MS-15 piston ring set is built for performance engine builders who demand precision fitment and consistent sealing. File fit rings allow the builder to set exact end gaps for the specific application, making this set ideal for competition and high-performance street builds.