Oil Ring land thickness
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Oil Ring land thickness This is something I haven't thought about in a while.
I have a few sets of oddball pistons laying around that I picked up from a swap meet this past weekend.
I noticed that the ring land for the oil rings on one of them was super thin.
How much stress do the ring lands for the oil rings normally see?
These are forged aluminum pistons but the land for the oil ring above the pin hole is roughly ~1mm thick. I've never seen a piston that thin before.
I guess this explains the super low compression height.
I have a few sets of oddball pistons laying around that I picked up from a swap meet this past weekend.
I noticed that the ring land for the oil rings on one of them was super thin.
How much stress do the ring lands for the oil rings normally see?
These are forged aluminum pistons but the land for the oil ring above the pin hole is roughly ~1mm thick. I've never seen a piston that thin before.
I guess this explains the super low compression height.
Since it is just there to scrape oil off the cylinder wall, it seems like there wouldn't be much stress on it at all. Perhaps once things wear and you get more blowby past the compression rings, the oil ring could get beat up a but. Times of detonation and similar negative occurrences could cause some stress too. My amateur assessment is that in a properly running engine, the oil rings is just hanging out.
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I'll have to snap a picture, but I guess I haven't quite explained just how bad it is.
The oil land is 1mm thick, and not just above the wrist pin, but across the entire pin face, so about 3 inches wide.
The oil land is 1mm thick, and not just above the wrist pin, but across the entire pin face, so about 3 inches wide.
If you're talking about the area under the bottom oil ring, in the 4" stroke pistons, the pin often intersects the oil ring groove so there won't be anything there at all. You usually have to use a support rail to go under the 3pc oil ring.
What brand/part # are those pistons?
I think with the relative low-stress life of the oil ring it probably works fine but I don't have much experience with broken lands. Never seen a broken oil ring land but I haven't seen a lot.
Edit: Also it occurs to me that the major stress is going to be on the power stroke, piston moving down, bottom land is under no load at that point..right?
I think with the relative low-stress life of the oil ring it probably works fine but I don't have much experience with broken lands. Never seen a broken oil ring land but I haven't seen a lot.
Edit: Also it occurs to me that the major stress is going to be on the power stroke, piston moving down, bottom land is under no load at that point..right?
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What brand/part # are those pistons?
I think with the relative low-stress life of the oil ring it probably works fine but I don't have much experience with broken lands. Never seen a broken oil ring land but I haven't seen a lot.
Edit: Also it occurs to me that the major stress is going to be on the power stroke, piston moving down, bottom land is under no load at that point..right?
I think with the relative low-stress life of the oil ring it probably works fine but I don't have much experience with broken lands. Never seen a broken oil ring land but I haven't seen a lot.
Edit: Also it occurs to me that the major stress is going to be on the power stroke, piston moving down, bottom land is under no load at that point..right?
I'm not so much worried about stress as I am piston rocking in the bore, eventually taking out the weakest link.
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Well sir, then all I can recommend is keeping the detonation/knock/rock down on your "privileged" pistons. I would run them. But I'm by far not an expert.
If you think about the piston rocking in the bore with the pin being the axis along which it moves, the top of the piston will impact the bore before the oil ring area would. Piston moving around on a floating pin, it would all hit at the same time at least. Also the skirts are positioned where the majority of concern is right?
Did you consult the secret mfg?
If you think about the piston rocking in the bore with the pin being the axis along which it moves, the top of the piston will impact the bore before the oil ring area would. Piston moving around on a floating pin, it would all hit at the same time at least. Also the skirts are positioned where the majority of concern is right?
Did you consult the secret mfg?
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I asked them. They still want them tested before they make any changes.
These are basically Chinese forged pistons for the LS. I talked my way into getting a set to test, cost me a whopping $165. They're forged in the same factory as some of the name brand slugs.
Metallurgy tests show they are basically the same strength 4032 as any domestic pistons. I'm still squeamish about the ring land. The plan was to build a 370 with these pistons, put in on the dyno with a pair of billet 78mm turbos and see what gives first.
These are basically Chinese forged pistons for the LS. I talked my way into getting a set to test, cost me a whopping $165. They're forged in the same factory as some of the name brand slugs.
Metallurgy tests show they are basically the same strength 4032 as any domestic pistons. I'm still squeamish about the ring land. The plan was to build a 370 with these pistons, put in on the dyno with a pair of billet 78mm turbos and see what gives first.
I don't know what to think about that. I guess if I had a throw away or a test engine that I didn't really care if it lived or blew up, I would try it. Radial load on the area there shouldn't be very much, if any, but I don't know what kind of axial load it has as the ring moves up and down in the groove at 6000RPM+. At that speed, grams turn into pounds.