I keep reading about stiffer blocks and cranks. Well, maybe the blocks if going from grey cast (20 million PSI) to nodular or Compacted Graphite (25 to 30 million PSI).
For the cranks, however, if we start out with a standard stock forged crank and change material to 4340, it is maybe 3% stiffer.
When we change the journal size to smaller diameter the crank loses stiffness, it is a natural fact. There is no material that is stiffer than steel that a crank can be made from, except molybdenum, and I don't remember ever seeing molybdenum in its pure form, ready to be cut into a crank. Plus, moly is about 30% more dense than steel.
R.
I wasn't just speaking to hardness, but to overall rigidity in particular. That's why you can take a stock block and put a girdle on it and do very little to overall strength.
Buy an aftermarket back and it it much more rigid and it weighs more.
As far as cranks, the stroke on a PS is relatively short for its displacement. Counter weight placement can make a crank less prone to flex.
