what causes bearings to spin on ls/vtecs?

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Dark93DX

New Member
I see this has happened to quite a few setups, is it just from overreving or ppl not using ARP rod bolts and the stock rod bolts stretching? lack of oil, ie improper (non-vtec) oil pump used?
 
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Sounds like an expensive way to rebuild a motor;)


Since we're on the subject.....Can LS/b20 rods withstand 8000RPM and last reliably? obviously I know that the rod bolts are weak and their getting replaced with ARP's, but what about the rods themselves?


Thanks,
 
heres the thing ls b18b are one of the strongest blocks madeout of a honda/acura yes man the bolts are weak/ the rods are sturdy but honestly if your gonna build the motor "hardcore" to say i would do the block and put a gsr head with type r internals unless you got parts. ? YES THEY CAN HANDLE UP TO 8500 I WOULDNT PUSH IT THAT FAR ALL THE TIME THOUGH JUST ever once in a while but the reason you cant beat on them is plain and simple there really not made to be together your fabricating 2 motors to work that werent made 2.. unless you put some mucho money down ....

i would go b20 block type r head and k pull bitchs. lolol
 
If the b20 block is legal where I live (still trying to find out) then thats the one I'm building b/c I can get one for $400. Since I'm going with forged pistons anyway I'm thinking I might just put up the cash and get some Eagle rods as well since they come with 3/8" rod bolts anyway. I may get the crank balanced at a local machine shop as well, but not sure if thats really necessary.
 
i hope i get this right!!!!
in the words of BLANCO-the crank is balanced from the manufacturer
 
Interesting, didnt know that. Well thats one less thing to worry about.



on a side note my d15b is approaching 350k and still going:D


Cheers,
 
another interesting tidbit, as soon as a "newly balanced" crank gets covered in oil, spinning around in a fog of oil, it's right back out of balance. unless the crank in question wasn't in an engine when i obtained it, i wont have it balanced either. on the converse however, if a crank was not in a motor (meaning it was stored in someone's garage for xx amount of time) i'd have it checked for straightness and balance. if the journals are scored/galled in any way, i wont even bother trying to have it micropolished. cranks aren't difficult to come across, and not worth buying sub-par.
 
another interesting tidbit, as soon as a "newly balanced" crank gets covered in oil, spinning around in a fog of oil, it's right back out of balance. unless the crank in question wasn't in an engine when i obtained it, i wont have it balanced either. on the converse however, if a crank was not in a motor (meaning it was stored in someone's garage for xx amount of time) i'd have it checked for straightness and balance. if the journals are scored/galled in any way, i wont even bother trying to have it micropolished. cranks aren't difficult to come across, and not worth buying sub-par.
i had my LS crank Micropolished / HEAVILY knife edged. following that i had it balanced. i rev it to 8500 tuned, never
had an issue.
and its in a 85mm 12.2 comp
 
ok, that doesn't mean it was worth the money however. knife edging a crank will make the engine rev faster, just like getting a lighter flywheel. for a street driven car however, removing mass from the counterweights can cause more stress on the engine, due to increased harmonics. you probably had a nice setup, but unless i was building an all out race motor (something that i'm not interested in, i need to maintain some level of civility in my engines) i wouldn't knife-edge or balance. i'd just properly blueprint all clearances in the block, then move on to the head to make power. reliability is easily produced in the block, power easily in the head. in my opinion it's not worth it to try it the other way around, small gains for large compromises.
 
I see this has happened to quite a few setups, is it just from overreving or ppl not using ARP rod bolts and the stock rod bolts stretching? lack of oil, ie improper (non-vtec) oil pump used?

Lack of oil consumption/flow, incorrect torque specs on the rod bolts, incorrect bearing clearances, out-of-balance crankshaft (not so often) and ofcourse... over-revving. I don't care how built your engine is, what valvetrain components your using, IF you retain the rod stroke ratio of the b18a/b, than that engine will be safe to rev to 8k rpm max. I dont care what your friends cousins brother had in his ls/vtec, facts are facts... Long rod stroke, no high rpm. Short rod stroke, high rpm.
 
ok, that doesn't mean it was worth the money however. knife edging a crank will make the engine rev faster, just like getting a lighter flywheel. for a street driven car however, removing mass from the counterweights can cause more stress on the engine, due to increased harmonics. you probably had a nice setup, but unless i was building an all out race motor (something that i'm not interested in, i need to maintain some level of civility in my engines) i wouldn't knife-edge or balance. i'd just properly blueprint all clearances in the block, then move on to the head to make power. reliability is easily produced in the block, power easily in the head. in my opinion it's not worth it to try it the other way around, small gains for large compromises.

I agree with you 100%. Knife edging a crankshaft is for race purpose engines. Doing this, either way will shorten the life span of the engine drastically. Knife edged crankshafts are only good for 1 season.
 
thats why i did it! :D race engine, length of life isnt a concern to me
 
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