cab's got it....detonation can instantaneously inflict huge damage to the bottom end...and the more power you make the more severe the destruction.

if you are racing you have to determine whether the cost of keeping a stock block alive is worth the extra cost of bullet-proofing the bottom end...and even then it's how the top end is tuned that makes the real difference. For me I'd rather build an aluminum rod motor with a stiff cradle around my crank than stiff rods inflicting a pounding into a bottom end designed to effectively "flex". I'd rather have a dead-blow hammer banging into a strong anvil than the other way around...but opinions vary

George, at 600hp you'll probably have a fairly mild converter in it so the shock loads onthe line won't be as severe as they might be in a stick car or a TB/high stall FB racer....even with the weight a converter cushoins the radial and axial loads on the crank. at that power level I think you'll be ok. Ductile caps are good insurance as is a Girdle but at 600 I think you're probably ok......a 500" motor that peaks around 600hp is going to have atorque peak fairly low (maybe 4200rpm) in the powerband, the lower the RPM, generally the better in terms of crank flex and block longevity.