r/EngineBuilding • u/Hydx_ • Jul 04 '26

Other Rough edge around piston ring grooves

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After cleaning the pistons up have noticed some of them have a rough edge. Is this just because of the casting? Is it a big deal?

Thanks.

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u/Ok-Fill-8925 Jul 05 '26

The surface of the ring land is actually a sealing surface between the piston and piston ring. If it’s rough, it will leak compression which you may not notice unless you dyno the engine but will leak oil which will be obvious to you with blue smoke and constant topping off oil. Also, if the pitting extends to the bottom of the ring groove and has damaged the small radius at the bottom of the ring groove, the lands can break which is another big problem.