Horsepower/rpm limit for stock, cast 454 GM crank.

[Joe Kraemer]

I thought a good machinist used a 5 pound hammer on a crank to straighten it because he flat knew what he was doing.

pdq67

I have seen lots of cranks straightened with a big hammer and a rounded chisel.

[rally]

Dont like hammers to straighten a crank. I had mine straighten with a hydralic press machine. This guy knew what he was doing,

[digger]

I thought that cast iron flexed less than steel and canceled out vibrations.
Has anyone seen a steel mill or lathe?

Erland

it does not have less flex, it has higher internal (structural) damping especially gray cast iron, ductile iron has as well but the difference between it and steel is not as pronounced as gray CI. this means when resonance occurs the amplification will be lower but it is not "stiffer".

[Erland Cox]

OK, thank you!

Erland

[vortecpro]

We ran the GM cast 454 crank in our super comp doorslammer in the early 90s, and it was replaced every 200 runs, why, because it had cracks EVERY time we wet magged it after 200 passes.

[rally]

vortecpro what RPMs were you turning and what compression ratio was this 454 cast crank super comp engine? Still its impressive getting 200 runs on a cast crank. Advantages were a lighter rotating mass with the cast crank?

[vortecpro]

vortecpro what RPMs were you turning and what compression ratio was this 454 cast crank super comp engine? Still its impressive getting 200 runs on a cast crank. Advantages were a lighter rotating mass with the cast crank?

12.9 comp, 7500-7700 RPM. Advantage was it was cheap, and thats the only advantage. Cranks were changed every 200 runs. The problem is the external balance, probably not a good idea to have a big ol counter weight on the balancer, theres your problem, but the cast 396 cranks break too.

[dfree383]

I have a 460 Ford making 800hp on a factory stroke cast crank at 14:1.

I have had a number of them over the years making well over 600hp on cast cranks.

But to be fair the Ford stuff is only 3.85 stroke, does have a rather large rod journal with alot of overlap and Ford always seemed to use better metal in the castings than GM.

[lorax]

vortecpro what RPMs were you turning and what compression ratio was this 454 cast crank super comp engine? Still its impressive getting 200 runs on a cast crank. Advantages were a lighter rotating mass with the cast crank?

Hellion Power System would get about 150 to 200 runs from a 351W crank before seeing cracks as well. Interestingly, the crancks tended to run length wise on the journals like a billet, as opposed to around the fillet area. There would be numberous cracks,, small and short, but the crank would still be in one piece

I have a 460 Ford making 800hp on a factory stroke cast crank at 14:1.

I have had a number of them over the years making well over 600hp on cast cranks.

But to be fair the Ford stuff is only 3.85 stroke, does have a rather large rod journal with alot of overlap and Ford always seemed to use better metal in the castings than GM.

Not only does the overlap and stroke make the Ford crank stronger, but the material is much better as well. The later GM stuff is better, but those Ford cranks are tough.
Ford was racing 500HP 427s with cast cranks when GM would never think of it.