8.1 , broke piston , help , ideas??? Pics inside. This is not your average thread!=)

[fatblockvelle]

OK ... Need some 8.1 help here. I am far from a guru and dont claim i know everything... but my number 5 cyl is down on compression.... =) number number one is broke and number 7 is cracked.... has anybody ever seen anything like this before?"?? have a bent pushrod in #5 but im sure has to do with vanishing piston trick. question to you guys is... im tossing another motor in this car and i dont want to have same issues... this motor was in a bread truck and was tmu. One more question... does anybody know if gm stamps the pistons from the factory like that" or someone rehash this thing???? ??? sorry for the ramble ... THANKS FOR ANY HELP!!!!

[fatblockvelle]

Top Of Rh Piston All But One Is Cracked.

[Montecarlodrag]

Can you post the tune from that engine's PCM?

[mecanicman]

I have taken one apart that looked like that, was detonation that killed it. Pics are to shiny to see the tops of the piston well, are they pitted? I believe the gm pistons were marked on top like that.