In Reply to: Re: Piston rings posted by Bruce(OR) on January 19, 2023 at 20:53:09:
I figure that in designing the 8N they considered the 4th ring not necessary and eliminating 25% of the friction and machining the groove was worth it. Lands and grooves and skirt length are the same. Not sure if an open groove puts much additional oil on the walls and possibly ups oil usage. Someone in one of the forums said they had used three rings on a four groove piston, but did not say anything further.