/6 crankshaft balancing

[pishta]

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.

 

[slantracer]

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.

A NA race slant can twist a forged crankshaft, I have proof. Would that break a cast crank?

 

[pishta]

I dont know. Being more brittle than forged, I'd say its a possibility. Judging by your pic, I assume yours is a drag motor with a dumping clutch or high stall and maybe a line lock? That would put lots of stress on any crank. On a road course, you would benefit from a lighter crank.