Stock cranks strength

[Turbo317]

How strong is the stock crank? and how much can it be turned?? i spun some mains again and not sure if the crank can be saved this time?

 

[750H.P.V6]

I would tell you that I've built a couple of motors with cranks that were 20/20 and they are alive and well. I would be concerned if you had to turn it more than that. It would be more a question of what kind of stress had been put on the part by the time you have to turn it say 30/30. Cycle fatigue is cumulative and can't be measured with a micrometer. I'm sure someone will chime in and say they're running a non turbo crank that's 40/40 in the 10's for 5 years but I'd tell you if it needs to go more than 20/20 junk it.

Neal

How strong is the stock crank? and how much can it be turned?? i spun some mains again and not sure if the crank can be saved this time?

 

[turbo buicks]

I'm sure someone will chime in and say they're running a non turbo crank that's 40/40 in the 10's for 5 years but I'd tell you if it needs to go more than 20/20 junk it.


ya right ive been running a quad turbo crank thats 04/04 in the 5s for 10 years now but id tell you if it needs to go more than 20/20 junk it.

 

[Ormand]

I'm with Neal on this one. The problem is that the turbo cranks had the rolled fillets to improve FATIGUE life, not to add more strength. So the na cranks will handle just as much power as the turbo crank, but for less time- fewer cycles. And since the fatigue is cumulative, there's no way to know how much has been "used up" over the years. The rolled fillets should survive 20/20, and maybe 30/30, but there's no way to know for sure, unless some of the fillet is still visible after the crank has been turned.

 

[Turbo317]

thanks for the info, my crank was cut 20/20 last time, looks like im buying a new crank!