Carrillo RS1MGNHD-4125 Race Series Piston Ring Set 4.125 in. Bore

The Carrillo RS1MGNHD-4125 is a Race Series piston ring set engineered for high-performance and racing applications using a 4.125-inch bore. This ring pack is designed to pair with CP-Carrillo Race Series pistons and delivers exceptional sealing, reduced friction, and superior durability under extreme engine conditions.

The MPN encodes the full ring specification: a 1.2mm gas-nitrided steel top ring provides outstanding durability and reduced friction compared to thicker 1.5mm or 1/16" top rings. The 1.2mm Napier (hooked-face) second ring improves oil control over conventional taper-faced rings by acting as a wiper to push oil away from the combustion chamber. A 3.0mm oil control ring completes the three-ring package.

Ring Pack Specifications:

• Bore Size: 4.125 inches
• Top Ring: 1.2mm gas-nitrided carbon steel — light gray in appearance
• Second Ring: 1.2mm Napier (hooked-face) design for improved oil control
• Oil Ring: 3.0mm three-piece oil control ring
• Ring Series: Race Series 1 (RS1)

Key Features:

• Gas-nitrided top ring for maximum surface hardness and wear resistance
• Napier second ring geometry reduces oil consumption and improves ring seal
• Engineered to CP-Carrillo's tight tolerances for optimum bore fit
• Compatible with lateral gas port pistons for enhanced ring seal under combustion pressure
• Designed for use with plateau-honed cylinder bores (35–40 degree cross-hatch angle)
• Made in the USA by CP-Carrillo

Always verify ring end gap before installation. End gap requirements vary based on application, forced induction, and bore size. A torque plate should be used during honing for maximum ring seal. Replacement ring sets must be CP-Carrillo brand — OEM rings are not compatible with CP-Carrillo piston ring grooves.