You are missing my point.... I never had any issues until I both was running 100% denatured alcohol and LUGGING the vehicle to get some logs at low RPM.
This is not something one would ever experience unless you did what I did. Effectively I got way too much fluid, gas and alcohol in the cylinders, relative to the amount that could be compressed without causing ring land fractures. As I stated, my engine ran fine above 2500 rpm. The fractures lowered the compression ratio at low rpm due to the air seaping by the rings. At higher RPM the rings held the compression just fine. One rod had a slight "S" bend that was almost invisible, unless you compared a straight one with it. Had some minor scuffing in that cyl on wall.
You are much more likely to fry a piston due to a lean condition, than what I did.
As for Methanol... anything 50% or more is flammable. Obviously the higher the percentage, the higher the octane and the more flammability. I had been running about 70% methanol, but I feel that the important thing is to be sure you are tuned for the % of methanol you are using. 50% - 75% -100% whatever... The only reason one should consider 100% methanol is that we need more fuel if one is using a 3 bar sensor and seeing boost levels in the 17-19PSI or higher (depending on turbo output).
However, the 100% dentatured alcohol would have worked just fine had I not lugged the engine. It might not have performed as well as Methanol, but if tuned properly for it, it works almost as good, relative to it's octane.