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Help- Whats Best Brand Main And Bigend Bearings?

sky30

By sky30,
in Engines & Forced Induction

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sky30 Mentor

sky30

Posted
Posted

Hi
Looking for some advice from people who have built high horsepower rb engines, what is best wearing and consistent engine bearings Acl, king, ndc, or any others?

Ive heard acl can be inconsistent, meaning one set is good another set is out of spec, any truth to this?

Cheers

GTRPSI Mentor

GTRPSI

Posted
Posted

Best wearing....

Bearings seperate the crank and rod journals with a coat of oil, if theres contact, dont blame the bearings.

Maybe you meant best to support loads on them.

Ive never had a issue with ACL, talk of specs, well you measure everything twice and again another time to be sure and ive never had a issue with ACL bearings being wrong or out of spec.

They even have a extra mains thrust face oil slot to lube the thrust face for heavy clutch pressure plates and good crush on them too.

Half sized oversized shells that you can mix with stock sized shells to bring clearances exactly where you need them when chasing a littler extra clearance in a performance engine running thicker oil....

Its not just the brand of bearing, its also the clearance your targeting, oil pump you will be using, viscosity of oil and intended use of the engine.

If your building something for 600Kw and running 30 weight of oil through a N1 pump on loose clearances, bye bye whatever bearing your running.......

sky30 Mentor

sky30

Posted
  • Author
Posted

Best wearing....

Bearings seperate the crank and rod journals with a coat of oil, if theres contact, dont blame the bearings.

Maybe you meant best to support loads on them.

Ive never had a issue with ACL, talk of specs, well you measure everything twice and again another time to be sure and ive never had a issue with ACL bearings being wrong or out of spec.

They even have a extra mains thrust face oil slot to lube the thrust face for heavy clutch pressure plates and good crush on them too.

Half sized oversized shells that you can mix with stock sized shells to bring clearances exactly where you need them when chasing a littler extra clearance in a performance engine running thicker oil....

Its not just the brand of bearing, its also the clearance your targeting, oil pump you will be using, viscosity of oil and intended use of the engine.

If your building something for 600Kw and running 30 weight of oil through a N1 pump on loose clearances, bye bye whatever bearing your running.......

Yea, as you put it, best supporting high load.

How many thou do you condsider loose clearance? And what weight oil at that clearance?

GTRPSI Mentor

GTRPSI

Posted
Posted (edited)

Thats a personal question, like asking a stranger what color of underwear they are wearing. :)

I wouldnt go over .0027" on mains and .0025" on big ends with a straight 50 weight of heated oil and engine for a drag spec RB30 engine around up to 900kw at the flywheel.

Yes its been tested, 1200hp RB30 engine pulled down twice on the dyno, no ACL bearing issues.....

There is a formula that ive used from the late 70's to calculate bearing clearances based on jounal diameters, its still being used today, its all over the web now.

0.001" clearance per 1" of shaft diameter to get a base figure which is the maximum for a stock build or the Minimum for a race build.

deduct 0.0005" to give minimum clearance stock build.

Add 0.0005" to give maximum race build.

Edited by GTRPSI
Scott Black Rising Star

Scott Black

Posted
Posted

ive used acl bearings countless times in engines that ive build threw work, never had an issue, only times ive had issues with bearings have been when im trying to get away with stuff i shouldnt, like keep a mates motor running for a bit longer after they have picked up the big ends, by just swapping them out with ones the right size and no maching. yet anyone who does something like that and has issues then blames the bearings are just stupid

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