Eagle Forged Stroker Crank CRACKED
if it makes you feel good or smart you can blame it on the balancer but do some research and you will find that 99% of crank breakage are the shitty Eagle cranks . The balancer might be the cause but it seems the other cranks can live through it but the Eagle can't .
When was the last time you saw a 3.58 stroke cast crank fail??
I can’t think of it either. So what is that telling us? Is it telling us Eagle makes junk ****? That the cast Eagle crank (that comes out of the exact same foundry as every other Chinese crank) is inferior in materiel?
That’s not what it’s telling me.
What I’m saying it says is when guys buy these cast cranks they are using the cheapest damper that can find (its not a ”balancer” and it has never been a “balancer”) and send it.
And IF that’s the case, in all likelihood that damper is tuned (at best) for a 3.58 stroke cast crank, not a 4 inch stroke crank. Also of note is the fact that I doubt the Chrysler production cranks used the same materiel as the Chinese cranks, and the topic of which used the better material is open for debate but I doubt the Chinese cranks are at least as good a material as the OE cranks.
So let’s say they are the same materiel. A .420 inch increase in stroke length most certainly changed the resonance frequency of the crank. And if the damper isn’t tuned for that, you’ll get a failure, just like we see in the pictures.
But, let’s say the Chinese cranks are a better materiel. Now you’ve added a bunch of stroke (changes the resonance frequency) AND the materiel is different and that changes the resonance frequency. And the damper was in no way tuned for that.
The OP also changes to a hypereutectic piston and THAT changes the RF of the assembly. I’m betting the damper wasn‘t tuned for all that.
What about the connecting rods? If those are a different materiel than the OE used, then that is another change in RF that the damper can’t deal with.
Even a change in gear ratio affect damper tuning because the elastomer damper (especially bonded type the OP used) has such a narrow range that a change in cruise RPM can put the crank assembly into a place where it is constantly excited and you start to get fractures and then failures.
I can’t count how many cranks I have wet mag’d but it’s enough to know what I’m looking at.
The biggest crank breakers ever was the Moroso solid aluminum hub. That piece of **** broke more cranks than all other shitty dampers combined. And Moroso sold the hell out of that junk and guys bought them because they were the lighted damper on the market.
What good is light if it kills the crank on a regular basis?
That crank failure IS a damper failure. The damper was totally incapable of controlling the harmonics off the crank for whatever reason. That’s the fact.
Can we say the Eagle crank is more prone to failure than other Chinese cranks because of where the lightning hole in the rod throw is in a different place or it’s too big or both? Certainly. But thats not why it failed.