Crankshaft issues
- Thread starter IdahoRob
- Start date
Built motors make more power and are pushed harder. One of the big problems is it's still the same block. I think the block is past its limit.
According to Tony, he says it has some vale to those that are looking for something stronger..
as for the crank, I feel its the same as everything else, we are simply pushing it past its limits. The crank at one time was not really a weak link. It did its job when rods bent and pistons cracked. However now we are coming to the next link in the chain...
Guy, or anyone else, what sort of testing is avail for a crank? short of putting it in a truck and seeing what happens. Is there a bench that can test different types of loads and such?
as for the crank, I feel its the same as everything else, we are simply pushing it past its limits. The crank at one time was not really a weak link. It did its job when rods bent and pistons cracked. However now we are coming to the next link in the chain...
Guy, or anyone else, what sort of testing is avail for a crank? short of putting it in a truck and seeing what happens. Is there a bench that can test different types of loads and such?
To be honest guys I'm totally amazed how strong these things are. We are pushing them what, 3 to 4 times what they were originally intended to do? We will continue to push them and find the next weakest link. That is the name of this crazy game we play and I'd be willing to bet, (although they would never admit it) there are GM engineers who watch our forums and threads to see what is happening in the big power game and we do influence their thinking when it comes to new designs.
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Just like the piston cracking problem... low and behold the LML's have a redesigned piston.
The LS world went through this years ago. Pistons, rods, cranks and then finally blocks were replaced with forged and billet pieces. I think there are 3 or 4 aftermarket blocks; iron and solid billet. Even GM stepped in with the LSX iron block.
Sorry missed your edit. The shop we have working on the engines is a shop near Boise with a long and successful track record building big hp gasser race engines. Also a fair amount of work on diesels but nothing like Max'd Out. Block is fine. They seem to think the girdle will help what ours was doing a lot. Ours was moving side to side and not back and forth. They already had the main caps redone and everything aligned honed so the billet main caps will not go in this engine. The argument as I understand it before with billet main caps is the difficulty of getting them aligned honed perfect due to the difference in hardness of the material and the honing process walking a bit. I'm no machinist so if I'm explaining it wrong please correct me. Again we are at the 1300 hp mark with our engine. The first time we tried it at 100% power is when we broke the weld. The 9.71 pass was the #4 tune and Rob would have to tell you how much less it was than the full fuel tune.
well that's discouraging
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yes, Thanks Ken for sharing here. on Rick's site you said the block was reusable though correct? so it didn't hurt the mains too bad just the bearings? i was digging up some old threads on cap-walk and crank-walk on the DP and there were a few who thought that the girdle wouldn't mitigate the Crank-walk. I hope that it does help you guys, as i was really thinking about using one myself in this build. would a better balancing job ( not the normal zero-balancing) maybe be more beneficial? I know the Kuselicks were trying some new things this year with their motor and as i understood it, they had it internally balanced and not to zero (don't know if i am explaining that right). i don't know if it is feasible for a drag motor or not, as i understand this is usually common practice for pullers.
:hug:
Everyone knows that LB7/LLY rods bend... so us LB7/LLY guys have to address that problem. LBZ/LMM guys have to address their crack prone pistons. The reality is so many things can and do go wrong in engines that cause catastrophic failures. We will never have it all figured out, just look at the Cummins guys their engines have been out a lot longer than ours and they still have large failures.
I think everyone knows now, they ALL bend rods. To whomever still thinks they can put lbz/lmm rods in a 700+ hp motor and think they will be ok, well, it wouldve been cheaper to do it right the first time, cause there will be a second time.
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I thought about a girdle for a long time, didnt end up doing it this year, im afraid when you take the walk/flex out of the crank, you will just start getting more crank breakage, but i could be wrong, i hope theres more testing and it proves that girdles do help out. I think some of the breakage has to do with the gear drive up front.
Wild thing in our #1 engine was the crank held up to that much abuse. The caps were actually seperating away from the block under power. Caps were moving side to side, rocking and being pushed away from the block.
The block and crank were magged and are going back in. The main caps took quite a bit of work to be fixed.
Anything you can do to stiffen up the block will help with longevity, not necessarily HP. We can make the power easy enough, I want it to live for a season. Sure finding the weak links at this power level.
The block and crank were magged and are going back in. The main caps took quite a bit of work to be fixed.
Anything you can do to stiffen up the block will help with longevity, not necessarily HP. We can make the power easy enough, I want it to live for a season. Sure finding the weak links at this power level.
they did have the normal ARP main studs but with a girdle now, i believe they will have custom main studs, at least they will if they use Powermax's kit or any like it
