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PA070014
Shows a seized second ring. Note the lack of sealing shown by ringland.
Date: 07/10/09
Owner: nobody123
Views: 17
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PA070013
Top ring on left, second on right. Note the wear is twice the amount on top ring, mostly due to more gas pressure.
Date: 07/10/09
Owner: nobody123
Views: 14
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PA070015
Broken top ring.
Date: 07/10/09
Owner: nobody123
Views: 14
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PA070016
Same broken top ring
Date: 07/10/09
Owner: nobody123
Views: 14
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PA070017
The ring has broken allowing gas to bypass. The second ring cant cope with all of the sealing, and the oil control ring is designed to control oil, not gas. The gas has bypassed all rings, and allowed carbon build up, on the one side of the piston.
Date: 07/10/09
Owner: nobody123
Views: 20
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PA070018
Transverse oil slot. The Transverse Oil slot is to return oil back away from the bore. The lower scraper ring maintains the bulk of the oil, and any that passes it, is returned via the slot. Problem is the slot is approx 20-40% of the ring groove diameter. These pistons fail under heavy load, or abnormal conditions (detonation, pre-ignition etc) very quickly.
Cast pistons have steel inserts near the the pin boss, to restrict the amount of expansion, due to more material. The piston expands a little on the skirt sides, but because of the amount of material around the boss' the amount of expansion is far greater, hence steel inserts to reduce the amount. Note amount of carbon build up on ringlands.
Date: 07/10/09
Owner: nobody123
Views: 20
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PA070019
Same piston. The steel inserts have restricted the amount of expansion too much. Note the carbon build up.
The Transverse oil slot, also helps direct the heat from the crown, to the piston boss, and not the skirt. Once the heat is in the boss, it transfers to the pin, then rod and so on. This is the only advantage of a transverse oil slot. Because it restricts heat to the skirt, and forwards it to the pin boss, it allows a tighter piston skirt to cylinder clearance, which in turn results in a quiet engine.
Date: 07/10/09
Owner: nobody123
Views: 17
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PA070020
The top ring has suffered from heat. Most likely from pre-ignition or detonation. It has lost a lot of tension. The gap should be only marginally less than the second ring. Note the carbon on the second ringland starting to appear.
Date: 07/10/09
Owner: nobody123
Views: 19
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PA070001
Solid skirt piston. Much better option than transverse slot piston.
Date: 07/10/09
Owner: nobody123
Views: 12
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PA070002
Oil return drain. Hole on far left lubricates pin.
Date: 07/10/09
Owner: nobody123
Views: 12
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PA070003
Shows the oil return.
Date: 07/10/09
Owner: nobody123
Views: 19
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Detonation
That's ring land, not piston ring.
Date: 11/04/08
Owner: nobody123
Views: 75
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