Cast ironvs. Steel was Prowler V6

[G. Scott Ponton]

Greg,
    All points well taken but a few contradictions. If the steel part is so
much stiffer why does it have a harder time tampening tortional vibes.
Ductile essentially means "bendable without breaking." It is for this reason
all your points hold true. Other than the one about the block.
    The problem with the blocks isn't one caused by the stiffness or
flexability of the crank. I have tried running a steel crank in the same
app. The block broke in exactly the same way!!! The main caps and bolts are
not failing. What happens is the angularity of the rods causes the crank to
try and go through the side of the block.  The main area is just not strong
enough. Usually it will crack through the center three mains then continue
up through the cam bores. The only parts not broken are the #1 and #5 main
webs. Although I did have one that I was twisting to 7500 that had started
to crack through the front (#1) main too. A forged crank for a 455 is a
custom item and quite a pricey piece to have break in 6 or 7 pieces when the
block fails. Rumor has it someone is starting production on some new block
castings that have stronger main webs. Naturally they are also rumored to be
pricey too.  At the moment I don't have that much $$$ in the whole engine.

Scott