ring break in time

Bewy said

I get a laugh out of these idiots that put a freshly bored engine on a dyno for 30 min with WOT pulls & claim the rings are now 'broken in'. Broken might be the right word in this case, as the intense heat generated from friction from new surfaces getting acquainted might anneal the rings.

There is no set time for rings fully breaking in, but 2000 miles is a good number. Driving at 50 mph, it would take 40 hrs. Use mineral oil, then switch to your oil of choice.

And an 'in tune' driver you will notice the difference.....The engine feels more lively because it is making more hp from better ring seal & reduced friction.

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Nope. To anneal cast iron it has to heated much hotter than combustion temperature and remain there for 1-2 hours then cooled slowly. You ain’t getting to that temperature in a running engine. I’ve put a bunch of engines that have had minutes of run time on them, (just enough to do idle timing and carb adjustments) on the dyno and they go through a short dyno break in and then to wot pulls. And they typically come off the dyno leaking down between 3-6%. Load breaks the rings in. Period. Pat Musi was asked once how he breaks an engine in. Look up what he builds if you don’t know. He said “we start em and put em at 8500 rpm in the burnout box”.