The thread is almost 10 years old, but here is my suggestion. I have beat the ever loving snot out of a Scat cast 4” crank, Scat H beam rods. Shifting 6400-6500 rpm and 6700-6800 at the stripe. Changed pistons 5-6 years ago and had it balanced to 1/2 gram. New bearings. Still straight at that point. 50,000+ miles and has to be 2000 runs on the crank. With all that being said, buy a forged crank. The money is not that much more and our performance goals almost ALWAYS drift upward. I personally would avoid cast Eagle cranks. Go forged.
