There are lots of theories as to what cracks the main webbing in a typical 383 or 440.

Is there one thing that sticks out as the worst? I would guess detonation but I am usually wrong on these things.

So what is it?

Detonation

Raw horsepower

Compression ratio

Large stroke

?????

I am trying to learn here, and there are way better minds than mine that can give a educated answer. Maybe if Aftermarket blocks become available again this won't be such an issue.