[Raptor]

As mentioned, the primary reason for break in is getting the rings seated in. Before modern plateau honing methods, it took considerably longer as it was the rings job to level off the peaks left by the honing process (microscopic) Of course that wears the rings considerably more as well. Now days the rough honing is followed by a much finer hone that levels the peaks off so most of that process is already finished. In cases where plateau honing is used, the break in period is very quick almost as soon as the engine is warmed up. definately after the first few pulls. The main point is that in either case, the rings do not effect the cylinder wall nearly enough to leave any "guide" or retaining type ridge for the ring gaps to maintain a stagger. Just doesn't happen. In fact like I mentioned, they have more of a tendency to line up. I pulled another stock engine apart this week that 3 of the 4 pistons came out with all the ring gaps lined up. It had over 150K on it.

BTW, it is worth checking with whoever does you machining to see if it has been plateau honed so you know what is appropriate for break in. It seems like there are still quite a few shops that don't use it. They really all should.