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I bought and installed a forged stroker kit 2 years ago (4" on my LS1 bloc)
After a 1/4m run, i had a problem of low oïl pressure
I saw the crankshaft have problem on the two main bearing
I will find a specialist who can be turned .010, and 2 month after, he tell me the crankshaft is too twisted :-(
Now, i'm not not sure to want paid for another expensive forged crank just for continuing to be stroked, as i can have a stock LSA for free...
Also, i'm afraid to buy another, as the first was already forged, and had just 7500 miles...
It's a large cost for a few distance.
Should i have to buy exactly the same ?
I think yes because i have wiseco pistons and forged rods for this stroker
Well bad luck happen...I could talk about it for days since im the perfect example.
What brand if crank did you use ???
You already got everything setup for a 4 inch stroke crankshaft.I would go with another one.You could look at the for sale adds to find a perfect used one too save some $$$
Last edited by always faster; 12-27-2016 at 01:17 PM.
Coming from someone who builds engines, I often see brand new cranks that are bent right out of the box. It happens. From the cheaper ones to even some of the higher end stuff. Every crank I put in an engine gets checked (beyond putting it in v blocks and running a dial indicator over it because that only tells part of the story.)
Coming from someone who builds engines, I often see brand new cranks that are bent right out of the box. It happens. From the cheaper ones to even some of the higher end stuff. Every crank I put in an engine gets checked (beyond putting it in v blocks and running a dial indicator over it because that only tells part of the story.)
I do all the mecanic myself (with presious advice from friend who often done that)
I put only new good parts for not have to check them
If i have to check everything... my vette will not start again before 2050
(the pro who was the only one able to turn my crankshaft 200 miles around take 2 mounth just for check !!!)
Not sure my friend (some are pro) are able to check a crankshaft... and, as i'm in Europe, if it's not good, the return cost will kill me...
After a 1/4m run, i had a problem of low oïl pressure
I saw the crankshaft have problem on the two main**bearing*(tag on the main bearing of the middle and the*next)
I went to a friend who is mecanic for check**the**size*and if just a clean should be ok
Before cleaning, he saw 0.001" of difference**from**the *main bearing number 3 and 4 to the 1, 2 and 5
For him, after cleaning, it will be 0.002"*and*said *me is too much
The specialist i find was thinking he can cut the crank 0.010
After checking, he find the crank was twisted
He tried to "detwisted", without succes
And is it possible this machinist who is telling you this is wrong ?
It's always possible, but it's THE (only) specialist of my area (200 miles around) for engine internal (all engine, not US V8 only)...
And twisted in what respect ?
He tell me he cannot cut 0.010 because the crank himself is twisted... Don't know more
You could post if off to Dave Powell at Performance Unlimited in the UK, or the likes of Peter Knight, John Sleath etc to get a second opinion, unless there is another shop near you to use.
This would still be cheaper than buying a new crankshaft.
If you do source a new crankshaft, it will need to be balanced to suit your rotating assembly so to save that cost as well as the new crank it might be worth getting that second opinion.
No different than me having to post stuff from Northern Ireland. That's life I just have to pay to get stuff done, I get robbed all the time with postage.. Nothing I can do about it.
As hard as it is to find a competant and honest machinist here, I can only imagine what its like over your way.
I have had many lie, and many who were simply wrong.
One of the things I appreciated about the machinist I used for years [who sadly just retired due to failing vision] was he wold happily demonstrate his findings in the shop when he encountered a problem. Im sure he had forrgotten mor than i will ever know about precision engine building.
I would want to see for myself how he determined the crank was "Twisted".'Bent' is more likely.
Did you build the engine yourself? Even quality componants need to be checked, such as bore aliignment an, bearing clearances crankshaft endplay...
I would invest or borrow some tools and check for myself. Assuming the crank is out, mike all the journals for size and at several points to make sure they are round.Then, after checking your mains are aligned with a straight edge, rotate the crank with a dial indicator. If the mains checked round and are now out of round while rotating [and more likely the middle ones] you are bent. The only way I know to check for twist at home is to check the index of the crank. With the short block assembled, use the dial indicator to check TDC on each piston. Each should be excatly 90 degrees apart along the fireing order and the deck height should be consistent.
Someone else may chime in with a better way, but thats what i would do.Keep in mind if you buy new parts, you still need to check them.
I would assume a bent or twisted crank would show something on the bearings. Just how bad were they, any photos ?
I still dont get in what respect or plane it is twisted etc ? These damn cranks are so big and brutal....I just find it difficult to believe one would twist unless subject to very extreme conditions.
Unless somehow there was a manufacturing defect from the factory...again in which case bearing wear would be even more highlighting of a problem.
Also what were the specifics of the oil pressure problem, and how long had it been good for etc ?
A friend of mine will see the specialist today, ask about the twist, and take back my cranckshaft back... I will probably check myself... or find another specialist, but only in the future, and now, i want buy a new one...
As 2 of us send me MP about K1, i choose this.
Someone have a one of the best crankshaft grinders who will inspect and straight it if necessary
That is the destroyest bearing (with like an impact à the right side on the middle...
And this, the worst stuff on the crank
The oïl pressure was only at my second run... and the run was log... so, at the 2nd run, the oïl pressure was ok for the burn, all the 1st gear, all 2nd gear, and fall down whan i put the 3rd gear
i stop the car at the finish line, wait 10/15mn, restart and when i see no oïl pressure, i have stop
The day after, i restart, full pressure for 2 or 3mn, and when oïl begin to be at normal temp (just begin), the oïl pressure fall down
Check http://www.molnartechnologies.com/ Tom Molnar builds an awesome crank (and rods) at very reasonable prices. I use his stuff all the time.
Balancing shouldn't be an issue either. If you have a scale you can weigh everything and have it pre-balanced.You'll just need to rig something up where you can hang either end of the rod to weigh each end separately.
They even have a European distributor listed on their website.
I believe Tom was an engineer for Carillo for many years and really knows his stuff. Helluva nice guy as well.
Good luck!
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Was there any oil in the engine ? Are you sure it has had good oil pressure at all times ?
That isnt damage that has happened suddenly for no reason. Looking at it I guess there is a risk the crank is now badly damaged...but it certainly wouldnt have been the crank that caused the damage.
And as Andy says, whatever crank you buy will need balanced to suit your rods/pistons.
Although if a main journal is that bad....surely some of the rod bearings have spun or suffered damage, which can also render the rod scrap ?
12-27-2016, 12:54 PM
Forged crankshaft twisted, and now ?
