All of the exotic factory performance cars I have worked on which used
full 180 degree radii in the crank fillets have them rolled not ground.
That is, they roll the fillet into the web before grinding it (not
after!!). This is done to remove all stress concentrations from crank
forging/casting process and therbye eliminate fatigue cracking
commencing at this point.
Unless one wanted to go to the extremes of mathematically modelling the
journal under a range of dynamic stress conditions, I suggest only
practical racing experience with a particular crank would determine if
if a ground 180 radius would be OK
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