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Yup. Had the exact same issue with my crank. Cracked the rod journal on number 4. Rotating assembly was balanced with the harmonic balancer attached at the machine shop. My engine builder contacted had his contact threw Motovisty contact Manley and they said that its a common problem with these cranks around 650hp. Your best bet is OEM or Billet.
The simple solution is to not run 100mm cranks. Especially not in a 4g63 block.
This is in a 4g64 block.
Originally Posted by cficare68
Yup. Had the exact same issue with my crank. Cracked the rod journal on number 4. Rotating assembly was balanced with the harmonic balancer attached at the machine shop. My engine builder contacted had his contact threw Motovisty contact Manley and they said that its a common problem with these cranks around 650hp. Your best bet is OEM or Billet.
true, but these billet cranks are $1300. They could easily say it's 8 years old and anything can cause the failure and leave you hanging. So yes, there were labor costs. But OP doesn't need to buy another crank.
Originally Posted by Teal2nnr
My bad. Im glad they're granting warranty on your crank.
Originally Posted by 2006EvoIXer
That's awesome that a manufacturer stands behind their products.
Agree with all 3 of you. I expected a 20% off coupon at best..
Originally Posted by ayoustin
Post up some pics of the new crank's #4 journal when you get it. Manley was talking about redesigning their oiling holes to keep them from cracking. Curious to see if they're putting out revised cranks by now.
Will do. I expect it to be in hand middle of next week. Apparently its coming from Cali via pack and mule....
Nice ideas guys, I agree with much of what was said.
Something I always wonder about....
If we are looking at a crankshaft from the top, the power generated from pistons/rods 1,2, and 3 is transferred to the flywheel side of the crank through rod journal #4. ALL(minus friction losses and windage) of the power coming from 75% of the engine has to pass through that sorry little rod journal #4 before it can get to the final main journal and then the flywheel, at which point we can send it. Rod Journal #4 is also responsible for absorbing and transferring the power generated from piston rod assembly #4. The main journals are already thick as hell in diameter and have no trouble transferring the power of the adjacent cylinders through the crank, but how can we rely on one much smaller rod journal to do the same job?
Compare it to a gauge change in a wire. If you have someone using 0 gauge wire to send 150 amps into a room, but uses 20 gauge wire of equal length to connect it to the load, you're going to obliterate that 20 gauge wire if the load needs the full current. We are asking a lot of our cranks.
It's almost as if the rod journals would have to get progressively bigger as they approach the flywheel side in order to truly carry the power generated by the previous cylinders. The problem with this is that it puts the crank WAY out of balance and you would have to notch cylinders 2,3,and 4 to clear the larger piston rod big ends that would be needed lol. Thus, the solution was to build the crank out of a material strong enough such that the rod journals 1, 2, and 3 are over-engineered (stronger than what is needed) and #4 is good enough.
Solution: I think OEM crank, keeping it under 350 wheel trq,,,but that's not very fun now, is it?
I would hate to be a rod journal #4.
Edit: I did not take into account that the rod journal never actually see's all the torque at once. Only one cylinder fires at a time so it doesn't actually see the full power of the engine. Only 4 divisions of it at a different time. Man this can get out of hand fast...
Edit: I did not take into account that the rod journal never actually see's all the torque at once. Only one cylinder fires at a time so it doesn't actually see the full power of the engine. Only 4 divisions of it at a different time. Man this can get out of hand fast...
You do have all the counterweights spinning, so the energy is there. Also, max torque is the top 25% of piston movement from TDC of each power stroke (right after spark). Rotating energy is the average of all power strokes minus friction losses. So right when #4 spark occurs, crank at #4 rod bearing switches from being pushed counterclockwise (compression stroke) to max clockwise (power stroke). It is essentially part of the drag when #3 is in power stroke, and becomes the power source and pushes crank on both ends (connected to #3 and flywheel). Flywheel is the bigger resistance since that end is connected to 4 wheels, so it cracks from oil port to that end.
Last edited by 2006EvoIXer; May 11, 2018 at 11:08 AM.
think about this:
Red is tranny induced resistance to rotation in counterclockwise direction. Green is rotational energy from cylinders 1-3 carried by counterweights in clockwise direction. Blue is cylinder 4 from power stroke straight down and rotating with crank as it rotates (and power dimishing)
think about this:
Red is tranny induced resistance to rotation in counterclockwise direction. Green is rotational energy from cylinders 1-3 carried by counterweights in clockwise direction. Blue is cylinder 4 from power stroke straight down and rotating with crank as it rotates (and power dimishing)
That is accurate. Then there are the forces imposed from the crank pulley side, which are very, very small compared to the trans side, but existing and constantly changing depending on valve spring stiffness, alternator load, mivec gear position (for the IX's), power steering load, and air conditioning. The crank in general really does eat hell XD.
that #4 journal doesnt take anymore force than any of the other journals, however, it takes the same force more times.... it transfers all the power of #1, #2, #3 and #4.
where as the others only transfer the power of itself and the pistons "down crank" from it.
this is ignoring all frictional forces and any forces on the timing side of the crank.
that #4 journal doesnt take anymore force than any of the other journals, however, it takes the same force more times.... it transfers all the power of #1, #2, #3 and #4.
where as the others only transfer the power of itself and the pistons "down crank" from it.
i don't completely agree (mostly agree though). Each cylinder produces power for 1/2 rotation every other revolution. So I see why you say that it transfers power through entire revolution, every revolution. But the 1/2 rotation of it's own power stroke is different because the surge it gets at TDC. Cylinders 1-3 are averaged as it goes through crank to spin counterweights before getting to #4. #4 gets the shock at same time it is fighting resistance from flywheel and that energy doesn't get a chance to reach counterweight during launch.
Last edited by 2006EvoIXer; May 11, 2018 at 06:49 PM.
