When racing the Boss Bird Nitro engine, we ran Crower 4.25" stroke Billets. When trying to sort out the main bearing issues and oiling system in general, we bent the heck out of those poor cranks, especially the nose. We had bends at times in various locations of nearly .020"! We had those cranks straightened at least 3-4 times each, and right back in the engine for some more abuse. Never a crack. We simply couldn't afford to replace them. We were bending them every time out for a couple years. When we finally got the oiling system sorted out, no more bending. I guess I am surprised to hear of a billet breaking like that. Not questioning it happened, just surprised. The billet cranks seem to have a memory as well. Once bent, they seemed to bend easier the next time, until they were happy in the engine. In our case with the nitro engine that meant .0065" main clearance and 140-160 PSI oil pressure through the entire run. 43 GPM oil pump.
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