I have not used fill before, but judging from how many cranks have broken in girdled, filled, internally balanced, etc etc motors too, all the extra isnt worth it
Broken Crankshaft Count?
- Thread starter EDP
- Start date
I talked to Stevie about this. While fill, girdles, billet caps, etc do stiffen/strengthen a block and keep bearing wear more even if the block itself is flexing that much, you would spin a bearing long before you would break a crank from block flex. There are many truck with broken cranks without spun bearings so.... and I feel some of the spun bearings are occuring after the crank breaks and catches a bearing in the process. I've seen engines with spun bearings where the block, cap, and crank are bluer than blue and the crank has stayed together under power for a short duration (end of a run).
Either something inherent in the design and/or construction of the crank is causing them to break or it's from harmonics (or combination), but not block flex.
From what I understand there have been at least one or two aftermarket billet cranks fail as well. Were they internal or external? If internal, were they that way from day one?
Tuning?
What I don't get is why there are other trucks out there running more power and not having the same issue?
I would agree that most failures probably do come from harmonics and a deficient manufacturing on the ones that break. The one of mine that has broken wasn't tuning but there was some harmonics before the actual breakage and with most all of them breaking in the same place it has to have something to do with flawed manufacturing.
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As far as tuning:
Poor tuning can cause major stress and harmonics. The thing that leads me to a design flaw MORE than anything else, is a large majority break in the same/similar spot and in a similar fashion. It seems to be a weak point. If it was "just" tuning, I would think the cranks would be breaking in a multitude of different ways, yet these seem pretty consistent. I'm sure poor tuning will break one much QUICKER, but they shouldn't be breaking this "easily" in certain circumstances.
Some may have been manufacturered slightly different, have just a slight difference in metallurgy, and could be the reason for them lasting longer, but I'd be willing to bet harmonics comes into play as well. Some motors (even once balanced to the same degree) have different harmonics.
It seems one billet crank failed but it was driving a procharger (along with all the other front accessories), but has any other billet crank failed under normal configuration (i.e. not driving a procharger)? If so where did it fail?
On a platform different than the Duramax, poor tuning (such as detonation) can cause issues with a crank at MUCH lower HP than the crank will hold with proper tuning so HP is not the best calculator to use for measurement, and shows tuning plays a part, but the failures were not this close in nature (same spot, similar beach marks, etc).
Poor tuning can cause major stress and harmonics. The thing that leads me to a design flaw MORE than anything else, is a large majority break in the same/similar spot and in a similar fashion. It seems to be a weak point. If it was "just" tuning, I would think the cranks would be breaking in a multitude of different ways, yet these seem pretty consistent. I'm sure poor tuning will break one much QUICKER, but they shouldn't be breaking this "easily" in certain circumstances.
Some may have been manufacturered slightly different, have just a slight difference in metallurgy, and could be the reason for them lasting longer, but I'd be willing to bet harmonics comes into play as well. Some motors (even once balanced to the same degree) have different harmonics.
It seems one billet crank failed but it was driving a procharger (along with all the other front accessories), but has any other billet crank failed under normal configuration (i.e. not driving a procharger)? If so where did it fail?
On a platform different than the Duramax, poor tuning (such as detonation) can cause issues with a crank at MUCH lower HP than the crank will hold with proper tuning so HP is not the best calculator to use for measurement, and shows tuning plays a part, but the failures were not this close in nature (same spot, similar beach marks, etc).
although I can't prove any difinitive number of broken billet cranks, I am very confident from just talking to pullers at scheids and some people at the DPC that there have been a few broken even with girdles, awesome tuning, block fill, etc. None, of the builders that I know personally have ever recommened one, sImply because stock cranks have been working fine for the majority. Their failure rate is still relatively low. I'll be honest, this crank May have been doomed from the beginning. I bought it as a used motor, out of Tony's truck. To my knowledge it wasnt mag'd as part of the r&r before it was reassembled for me. It May have had a fracture then and is why it failed so soon. Also, it could have been tuning related at first that caused the stress, since it took so long to figure out how to make it run without doing something really weird. Who knows.
i have a question.
Guy showed me how the front main areas on these motors (where the bearing would go) were bigger than most of the other main bearing areas yet we still run the same size bearing throughout the motor. Is it possible that if we had a wider bearing made to go in on the front main area and machined in the block the little tangs to hold the bearing, it would support the crank enough and help reduce people breaking cranks? Or is this not as easy as im thinkin?
Guy showed me how the front main areas on these motors (where the bearing would go) were bigger than most of the other main bearing areas yet we still run the same size bearing throughout the motor. Is it possible that if we had a wider bearing made to go in on the front main area and machined in the block the little tangs to hold the bearing, it would support the crank enough and help reduce people breaking cranks? Or is this not as easy as im thinkin?
X2... Biggest thing Ive thought about.
Does anyone know how heavy the stock oem balancer is compared to aftermarket?
I'll have to check that out when I get mine apart this weekend. if this has been the case, then why haven't new bearings been brought to the market? why market the overpriced girdles, billet cranks, internal balancing, etc etc when they aren't really fixing the problem?
X2, we went to girdling them becuase the main bearings were getting the outside edges eaten off from block/main cap flex. We had to rebearing every season. JonJon was the first girdled motor we built back in the winter of 07-08 and is still going today in the 2.6 class at 900rwhp since the day it was built. He has the oil analyzed everytime and still no bearing wear todate. Truck started life as a 2.8 truck so it has not taken it easy. I girdle everything that we plan to run over 750hp for piece of mind. I feel that some are pure and simple weak part failures but some are definitely combination/harmonics induced premature failures.
i dont know, id really like to know if there is a big reason why. in a stock truck through the MFG process i can understand but in an aftermarket application, id like to see them come out or understand why it cant be done.
Im no genius, but my crack ended at the rod journal, started at the counter weight, which tell me its a leverage issue, not a balance or support issue because of narrow bearings.
Anyone know if the lml crank works in the lly block? Is it any stouter? My current crank is pitted and has runout, wanting a stouter option before I put this thing back together.