Piston Ring, Engine

Piston ring
End gap
Compression (top and bottom) 0.23 - 0.49 mm (0.010 - 0.020 inch)
Oil ring (steel rail) 0.05 - 0.66 mm (0.006 - 0.026 inch)
Groove width
Compression (top) 1.520 - 1.550 mm (0.060 - 0.610 inch)
Compression (bottom) 1.520 - 1.530 mm (0.060 - 0.0602 inch)
Oil ring 6.996 - 7.224 mm (0.275 - 0.2844 inch)
Width
Compression 1.49 - 1.47 mm (0.0587 - 0.0579 inch)
Oil ring rail (2) 0.473 - 0.447 mm (0.0186 - 0.0176 inch), 0.483 mm (0.0190 inch) maximum at ID
Oil ring expander 2.038 - 1.960 mm (0.080 - 0.077 inch)
Ring-to-groove clearance
Compression 0.030 - 0.070 mm (0.0012 - 0.0028 inch)
Oil ring assembly 0.046 - 0.196 mm (0.0018 - 0.0077 inch)