Is there any obvious damage to to piston it's self? Detonation or preignition will usually cause damage to the piston it's self or the cylinder head before breaking rings.
Are the ring lands deep enough to allow the rings to properly compress? As in are the rings the ones called for by the piston manufacturer, there has been a lot of talk about using pistons for other engines to increase displacement, not a bad idea when you can't get what was once available, but different brands use different engineering specs. I guess what I'm trying to say is that there could be many reasons for a broken ring and detonation isn't the most common, might be time to start to consider looking any and all possibilities.

Bore has no lip and i checked ring gap every time i had it apart and was always on the higher end of the spec, installation is not the issue either.

I think it may be detonation which is realy hard to hear over the engine and exhaust.

Rallytwit. How much total timing did you run with that much compression?

Once im done woth this new build I will stick to 98 octane to be on the safe side.

Maybe 30 degrees of timing would be safer than 32?

Compression will be around the 10.1 mark.

I've run 12-1 compression & 8200 rpm in the A15 and 11.8 compression & 8600 rpm in the A12. I've never had a ring break.

Something isn't right; either the ring end gaps or as rgrinder mentioned it snagged when the piston was installed.

I'm also not using any fancy rings just standard Hastings or other known brands.

Take a look at a few other things, it's possible that it broke during installation as in your ring compressor didn't fully compress the rings and the ring caught on the lip and got broken while being installed. Another thing to look at is if there is a ring ridge in the cylinder walls, Nissan blocks are hard and don't usually need a rebore from wear, but I have seen it happen on occasion. And as a last thought if the rings are too large for the bore as in insufficient gap when installed will cause rings to break, check the ring gap before installing them on the piston. Good luck.

Have a slightly worked a12 with a cam and h89 head and this is the second time i have broken the top compression rings.

The first time i suspect due to running to much timing. But when replaced the rings i put the timing back to factory 8 degrees and i just took the engine apart to put in some flat top pistons and all rings where good except cylinder 4 top ring was broken again.

Is this caused by detonation? Engine revs to 7500-8000rpm every know and then do i have to run less total timing then factory for these rpms?

Realy want to figure this out before putting the flat tops in and upping compression.