piston skirt ring

[elliottles1]

good day folks,

to anybodys knowledge, has a piston ring been tried, fitted below the piston pin but above the raised skirt sides, to help with piston slap? i had a barrel and piston in my hands the other day and played about a while and i believe it could be made to work.
it would obsiously not want to come out of the bottom of the cylinder sleeve but it looked do-able.
wondered if it had ever been tried.
just saw a porsche engine being stripped on tv, and they had exactly this on the piston, obviously 4 stroke so easier.

cheers
les.

[tony27]

Would think the skirt would be too thin to do that, guess you could try turning a groove to take a ring in an worn out piston to see

[rodneya]

Most performance 4 stroke pistons dont have very much skirt at all. On a 2 stroke I dont think it will do anything at all to stop piston slap, just add drag.
Anyway there is already a tried and proven way of preventing piston slap by running proper clearances and putting in new pistons when worn.

[teazer]

Rings are not there to reduce piston slap.  Their sole purpose is to create a seal between piston and bore.

A bottom (skirt) ring is not uncommon on some older diesel motors because they have "ridiculously" high compression.  The only practical way to reduce piston slap is to reduce piston to bore clearance.  There are other ways to reduce it by design such as changing bore and stroke and rod length, moving the piston pin higher in the piston, making the skirt longer so it rocks less and YES, some of those are headed in different directions as solutions.

BTW, Pistons are neither round not parallel. They are cam shaped and tapered so that the parts that get hottest, start off smaller so that at operating temperatures tjhe psiton is more or less the same diameter top to bottom.  They are cammed to created more clearance on the sides to reduce drag (friction) and that's why many 4 stroke pistons are of the so called slipper design, ie the sides are cut away from the pin down.

And as a prior poster mentioned, there's not enough metal in a stock piston to machine a piston ring groove.