<VV> 4340 crankshafts

[mhicks130 at cox.net]

4340 would be an almost ideal material to make crankshafts from.  When heat treated to the 160-180 ksi range, it has excellent crack resistance and fatigue strength.   If you heat treat to where it's impossible to machine, it does become more brittle (tensile strength is up near 300ksi though) - so don't do that.  

What's the stock Corvair crankshaft made of?  Hmm, if I wasn't so lazy I'd go open up the SAE papers book I bought, I think it's in there somewhere.

We used 4340 to make wind tunnel model stings out of because of it's strength and crack tolerance.  Good stuff.