When we think about piston ring seal, we generally think about bore finish and ring tension. But have you ever considered how a piston’s stability in the bore can affect ring seal? Well, Total Seal’s Keith Jones and Line2Line Coatings Andy Surman and Mark Gelstein sat down with Jeff Hammond in a recent EPARTRADE Race Industry Now weekly webinar to discuss exactly that topic.
If you were good in geometry class, you understand that a circle is only a circle in a single plane of reference. If you alter that plane, say by tipping the axis over a few degrees, the circle starts to become an oval. The same reason that we try so hard to keep a bore perfectly cylindrical, is why we need to keep the piston from rocking in the bore.
Piston rockover is a thing, and when it happens, it can allow the piston rings to break their seal to the cylinder wall. Now, rockover is a function of several dynamic variables that are going on in while an engine is in operation, and generally comes from the need for piston-to-wall clearance. Without that clearance, the piston would bind up in the cylinder and not move. Or would it?
This 53-minute webinar discusses how Line2Line’s abradable piston skirt coating can not only improve engine performance over its entire lifespan, but specifically how it can improve piston ring seal by not only preventing piston rockover, but by also keeping the piston centered in the bore during thrust events in the engine. This is no black magic or snake oil, but rather something that has been proven on the dyno and at the race track.
This webinar is certainly worth your time to listen to, as it will likely cause you to think about some things that aren’t usually at the front of your mind when building an engine.
Here you can see how excessive piston-to-wall clearance can affect piston ring seal.