<VV> broken rings

[djtcz at comcast.net]

the  exact same thing last summer and the rings were broken on 2 pistons.i wonder > what i did wrong on them? both sets of pistons , rings , cylinders , came from > the same source. i drive my truck a lot more than the other engine was > driven.(it was in a serious senior show car) i guess i better not plan on > driving it > on the club fall tour tomorrow..darn. i am glad it survived the vermont tour > ok, it had some heavy hill climbing there. lucky to get home with it. i know > one thing i will be doing this winter..as i prepare to move. > regards, tim colson 
>
I'd check on the condition of the parts for clues.  That would be all 6 pistons, rings, and cylinders, especially but not exclusively the ones that experienced the broken rings. Were the thin sealing rings broken, or the main rings ?  Were the engines built in the early top groove Total Seal days, or the more modern 2nd groove era?  If the rings were broken by mis-handling or installation in used cylinders with top ridges I'd expect the problems to appear quickly or right away.  If the rings broke from severe operating conditions then it would take a while.    Some events take a while to develop to a critical level , but then cascade or avalanche.  For instance, eventually insufficient crankcase ventilation maintenance (aided, but not eliminated by regular oil changes) can leave the oil rings and even the compression rings locked in their grooves by sludge, and susceptible to breakage by several means.  Low octane Oil in the combustion chamber can create combustion issues including detonation.  Under load combustion leaking past the rings can bathe the rings in fire. If the ring and groove wear becomes excessive then the rings will break into segments and really start tearing things up.

After a few years My Turbo Corsa was still running well, but I wanted to go through the engine.  The rings were not broken, but the top ring side clearance was huge, maybe 0.010 inch. The TRW rings had worn a lot.  The TRW pistons' grooves were also worn, but "OK". Maybe 0.005 inch side clearance with new rings. I had been running no shrouds summer and winter in New England, and often started the engine by winding the choke closed, then opening it manually after starting.  My theory was I had worn the rings from gas wash and oil dilution from the abusive choke use, the oil dilution aggravated by prolonged warm up.  
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 http://www.powroll.com/tech_specs_troubleshooting.htm
BROKEN RINGS
Insufficient ring end-gap 
Mishandling or breakage during installation 
Excessive piston/cylinder wall clearance 
Improper tuning – causing detonation 
Over-revving