Perfect Circle 40564CP-040 Moly Piston Ring Set Bore - 4.040

The Perfect Circle 40564CP-040 is a premium moly-faced piston ring set designed for 8-cylinder applications with a 4.040 inch bore diameter. Manufactured by MAHLE, the world's leading piston ring manufacturer, this set delivers OE-quality performance with advanced materials and precision engineering.

Key Features:

• 4.040 inch (102.616mm) bore diameter - 0.040 inch oversize
• Ring thickness: 5/64 inch, 5/64 inch, 3/16 inch configuration
• Moly-faced top compression ring for extended durability under severe conditions
• Cast iron top ring material with molybdenum facing
• 3-piece oil ring design with stainless steel expander and chrome-faced steel rails
• Pre-lapped rings for immediate seating and minimal break-in time
• Barrel-faced contact area for efficient compression and reduced blow-by
• Reverse twist intermediate ring design for superior groove side sealing
• CP-20 oil ring assembly with exclusive 20-degree ear angle for optimal side seal
• Complete 8-cylinder set (8 sets of rings included)

MAHLE Original piston rings feature SAE 9254 high alloy steel construction providing superior tensile strength, extended fatigue resistance, and increased material hardness. These precision-ground performance rings are designed for trouble-free installation and cannot be installed incorrectly, saving valuable installation time. Ideal for engine rebuilds and re-ring jobs requiring premium-quality components with consistent reliability.