nick watson

Just wondering if anyone could explain what the difference between these babies and standard rings is?

Thanks Nick

Scott Turvey

Relative to the LS1, it means the ring sizes and spacing. The spacing on LS1 piston rings is typically 3mm, 1.5mm, 1.5mm.

Old SStroker

The difference is ring thickness or groove width. 1 mm = .039 inches, 1.5 mm = .059, 3 mm = .118 inches, 5 mm =.197 inches. Nearest "inch rings" would be .043, 1/16 (.063), 1/8 (.125) and 3/16 (.188). There are other metric width rings used like 1.2 (.047 inches).

Metric dimensioned engines, which are most OEM now, pretty much stick with "hard" metric dimensions. There's not much difference in performance and drag from a 1.5 mm (.059) ring or a 1/16 (.063) ring. For aftermarket use, it depends on what the off-the shelf pistons are made with or for custom pistons, what ring widths are available in the bore you are using.

FWIW, stock ring groove size on a BBC 454 was 5/64 (.078), 5/64, 3/16 (.188), but the current 502 crate engine is 2.0 mm(.078), 1.5 mm (.059) 4.0 mm(.157). LS1 engines use 1.5, 1.5, 3.0 mm.

The diameter of the rings still has to fit the bore, no mater how it is measured, of course.

My $.02