Interesting balance video of a straight six crankshaft. The shaft itself is balanced to itself, not the reciprocating parts as they are their own counterweights as long as they are all the same weight. No need for the reciprocating weight when balancing a straight six crankshaft, each rod counterbalances its opposing rod(s) so there is no weird V8 reciprocating mass formula. So the later lightweight cast crank at -25 lbs is probably a better bet if one was building an all out endurance or race type mill, still plenty strong for a NA 6 output.
