Even in a mild case where the ring ends barely touch, the result can be a heavily scored cylinder wall and serious piston-ring-land damage due to this excessive load.Īn important note when filing rings with a manual ring grinder is to always turn the handle so that the abrasive cuts inward. We’ve personally witnessed the upper section of a brand-new hypereutectic piston that snapped off at the oil return slots from a seized top ring, due to insufficient end gap. With enough expansion, the ring can actually seize the piston. As soon as that happens, the ring can no longer accommodate further expansion and begins to tighten in the bore. If enough heat is present, the ends of the ring could even touch. Because the ring is contained in the cylinder, the initial cold gap will close as heat is applied.

As heat is applied to a metal – like a piston ring – it will expand. The issue that adds complexity is the engine builder must account for a given amount of heat in the cylinder. This is created to increase the volume in this area to minimize pressure buildup.įirst, let’s look at why there are differing gap specs. Also, note the depression between the top and second ring on the piston to the right. Normally aspirated drag engines will move the ring closer to the top. Supercharged and turbocharged engines tend to do this to protect the rings from excessive heat. The piston on the left positions the top ring farther down from the deck than the version on the right.

How to install rings on a namura piston