Have you ever seen this? 2016 2.5 Duratec engine Piston

[DaveH]

Assembling short block tomorrow. When checking the delivered piston rings for accurate measures I noticed this stepped slot in the second compression ring groove. When I pulled the engine apart I just discarded the old rings. I never noticed this "step" in the groove. I never recalled seeing this type of piston before. The second ring groove and second compression ring are correct for size but (why) would the bottom half be open? Just wondering.

 

[alwaysFlOoReD]

What do the rings look like? Any kind of taper on the face that contacts the cylinder wall?

 

[DaveH]

What do the rings look like? Any kind of taper on the face that contacts the cylinder wall?

Thanks for your response. Interestingly- after I posted this question I placed the 2nd compression ring in the groove and inspected with a loop. The second ring tapers. So the top of the ring is just a few thousandths inside of the groove as it should be. The taper is a few thousandths inside of the stepped down groove as I suspect it probably should be also. I just can't understand why this was designed this way.

 

[alwaysFlOoReD]

I think the ring flexes slightly allowing the face of the ring to scrap when going in a downward motion and slide over the oil in a upward motion. The groove allows the ring to flex more?
Edit; this is all just a WAG. Wild Ass Guess.

 

[pjtoledo]

the factory manual has some instructions that differ from traditional info. EDIT: well, sort of
I recently glanced at it, didn't study it yet.
I'll try to get some shots of it tomorrow.

this will be from a 2010 Fusion manual for a 2.5

 

[pjtoledo]

this is it, I'm not sure what it means about the right side

 

[DaveH]

Thanks guys, did a little research. I think these are "Torsional Twist" rings. The bevel is designed to "flex" to that side for increased sealing. As a WAG "guess" I suspect the gap is to control gasses or blow by that get to that ring.