A forged crank will "move" a lot more than a cast crank. "Stiffness" in crankshafts is not necessarily "good". A cast crank is dimensionally more stable than a forging. That's where the trade-offs begin. For racing, a more flexible crank is more "forgiving" and can stand higher revs. Internal harmonics play a huge role once RPMs go over 5,000. The "steel" crank (forged, NOT cast) is the crank of choice for this. Eagle lists their crank as "cast steel". That refers to the material, not the "process". When someone says "steel crank" in the vernacular, they MEAN "forged".
What Bruce says is correct, the larger main journal makes for a stronger crank. But again, stronger than what? The 3" main crank is NOT "weak", even WITH a 4.5" stroke. The block is of much more concern than the crankshaft in a Pontiac. Consider that big block Chevy has had a 4.5" stroke for many years in the aftermarket. They use 2.75" mains and 2.2" rods without issue.
Larger rod journals would also increase the sheer strength of the crankshaft. Again, no need.
Lastly, Eagle rods go out-of-round on the big end when the bolts are over-torqued. Been there, done that. We've had MANY BBCs over 1,000 HP with Eagle rods that show ZERO out-of-round after 500 1/4 mile passes. We have yet to experience a rod-related failure in a Pontiac equipped with Eagle rods. Agreed, Crower Sportsman rods and Crowerods (the famous billet) ARE very good rods. The latter perhaps the best steel rod available anywhere at any price. The Sportsman, however, is not competitively priced with other rods at the same level.
One of my purposes here is not to point at others and say "Wrong". It's to help bring Pontiac racers into the modern world by dispellng myths and superstitions. Since our shop builds as many non-Pontiacs as we do Pontiacs, we have an "edge" in this arena, as we see more "leading edge" stuff. What we learn from SBC, SBF and BBC (among others) applies directly to the old Injun, and improves it. My point here is to make sure it's clear to all, compare apples to apples, not to donuts. The Pontiac 3" main crank has another "edge" over the BBC and Dodge B and RB cranks, it's shorter. By about 3" from front main to rear. So let's not get carried away worrying about the strength of the crankshaft. The block will self-destruct LONG before the crank is at risk, provided clearances and oiling are correct.
FWIW
Jim
The Drunken Injun is on safari! (we're hunting elephants...)
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