Within reason there is no power or certainly no measureable power or useable power availble from reducung crank wieght so the engine can rev faster.
I doublt you could measure it . The mass of the vehicle exceeds by far any influence removing weight of the crank will. Notice I did say with in reason.
Crank needs to be strong. It is not the big problem weight wise that many hope it will be. I know a hundred will tell me I am wrong and that Bucky Wooppedeedo in Pensiltuckey Iowa put in a lighter crank and went four seconds faster but it just aint so. It is not that easy. Best place to reduce weight is con rod and pistons. That reduces load which is always nice provided strength is not reduced. Certainly one would not want a 500 CAT diesel crank in a 250 chev 6 but we are talking about a relatiely insignificant difference here.
But you know if it makes you feel better go for it. Beter yet run yer car with the 250 crank then change NOTHING but the crank (I mean it, no new spark plus and wires and fresh carb etc etc.) just change the crank and see what difference you get. That is how we test stuff.Sometimes we dont like the results but that is life. I would be surprised if there is any measurable difference but ol Smokey said "one test is worth a thousand expert opinions."
