What is the clearance of piston ring to block?

The clearance between the piston ring and the cylinder bore is essential to ensure proper engine performance and longevity. It allows for sufficient space for the ring to expand due to heat and prevents excessive friction. The ideal clearance varies based on engine design, material, and operating conditions, but typically falls within a range of 0.015 to 0.070 mm (0.0006 to 0.0028 in). Proper clearance helps maintain the seal between the piston and the cylinder wall, preventing excessive blow-by and ensuring adequate compression. It also reduces wear on the piston rings and the cylinder bore, contributing to the engine's overall health and performance.