I found a 4340 Eagle 347 Crankshaft that has been turned 20 thousandths. I was wondering about longevity and strength of a crank that has been turned. The engine it would go in would make around 525hp and be driven soley on the weekends and not driven during winter.
A crankshaft's life is better determined by it's previous use, not so much how much it's been turned. If the previous owner liked to feed the motor in which it was in large and frequent doses of "nos" or was fond of lots of boost , then I'd avoid it like the plague. There is a certain limit to any cranks life, in terms of rotation and abuse heaped on it, and it doesn't necessarliy have anything to do with the journal specs.