Cast crank destruction
 

Tis the season oi the 454 build posts. Now its common knowledge the cast crank is not good over 5ooo rpm or 500 hp etc... Just now I was scratching my head trying to figure out who has actually broke one?? I cant remember a post about anyone snapping or twisting one.... surely there are some good carnage stories out there...

You'll hear more rod / bearing issues vs. broken cranks. Cast will flex more under higher loads.

From what I have read Scat rotating assemblies = CAST crank.

last year one of the 340 hp 454,s in my cruiser would go to 5 lbs oil pressure within 10 minutes of startup.when i got the engine apart i found the three center main bearings were wiped out due to a cracked crankshaft.this engine rarely went over 3500 rpm and normally lived in the 1800 to 2200 rpm range.i doubt this would have happened if it was a forged crank.i will add that the engine had 1600 hours on it so it owed me nothing.

scat makes both cast&forged crankshafts.not everything needs a forged crank.gm made millions of engines with cast cranks.

Agree. The newer cast aint your fathers cast. No doubt forged is stronger but for example, Whipple, has done 800+ HP with cast cranks.

Just went over some of this on another thread. It's not necessarily cast vs forged (up to so many HP). Its more about what company it comes from. I bought a Eagle forged crank for a motor last year. By the time it was fixed it had to be cut 10/10 and we wont even get into balancing. At the same time I have had a Scat cast stroker crank in my 500hp 496 for the last 5 or 6 years. Knock on wood, never an issue with it.
In the past though I did see someone install a fluid harmonic balancer on a 1970's factory cast crank in a boat one time. Broke the snout off the crank. After much internet reading it was explained that the fluid balancers will settle if let to sit a long time (like over a winter in a boat) putting crazy stress on the crank when started until the fluid flows back to where it should be.

I talked to my machinist about this with my 408 Cu In small block Mopar builds for my Magnum. At My HP level (400-450) he recommended Forged pistons, but cast cranks. Mopars are a bit different in that they designed the 360 with a cast crank from the get go, and went with larger main journals to compensate for the cast vs forged strength issues.

I have only seen one broken cast crank, friends 454 el camino. I have seen several that were cracked, had the same problem that Mike had on his. of course they were not treated nicely so there is only so much you can expect.

You mean something like this? :D Buddy found this in his street cruiser....not sure the exact cause but he speculates the front cap was not torqed down 100% said it broke loose like he could have taken it off with his fingers... :(