detonation breaks the top rings.

Engine never ran in boost before the rings broke.

Momental,
You still have not answered the question as to what was considered a "new engine" The reason I am asking this is if the engine was "rebuilt" with new pistons, but without boring the block, the new pistons might have the top ring at a higher location compared with the old ones. That combined with a large wear groove around the top of the bore would break the rings almost with the first few revolutions. I can even imagine it happening with old pistons and new rings if the groove is bad enough.

Bill Koustenis
Advanced Automotive Machine
Waldorf Md