Jump to content
SAU Community

Rb26 Rod Bearing Clearances

Blue32

By Blue32,
in Engines & Forced Induction

 Share

Recommended Posts

Blue32 Experienced

Blue32

Posted
Posted

After rebuilding my RB26 with the following specs I have spun a bearing on no 2 after 2000kms. All of the other bearings are also hammered - and I believe it may be due to a clearance issue.

Here are the specs:

Aries Pistons and rings (86.5mm)

std rods with ARP bolts

ACL Race series bearings

STD oil pump (start the flaming....) oil pressure = 20psi hot at idle up to 80psi odd at high revs (ie good oil pressure)

Trust baffled sump (insert type, not weld on)

Castrol 10W60 edge syn oil

2xoil coolers

external filter block

Tomei head oil restrictor

The engine ran strongly and made good power (high 300rwkws), the knock recorded (pwr fc) was always <35, AFR always logged and spot on via laptop and wideband.

They should be the related specs required - please ask if you require more info.

My engine was built with around 2.5 thou clearance on the rod bearings, although the factory spec as per the manual is 0.8 - 1.5 thou. I am wondering if the greater clearance of 2.5 thou has killed the bearings and what clearances people are using in similar built motors of the same horsepower.

I am looking for ideas from people with EXPERIENCE / and or ENGINE BUILDERS of 400rwkw RB26 engines here - please don't post if you don't know what you are on about!!

Any help is greatly appreciated, I really don't want this to happen again!!!!

Cheers,

Andrew

Blue32

Link to comment
https://www.sau.com.au/forums/topic/232242-rb26-rod-bearing-clearances/
Share on other sites
MYRB30 Rising Star

MYRB30

Posted
Posted

Mines no fire breather, but my big ends were set around 1-1.5 thou and the mains I set at 1 thou. I was bit worried that the mains could have been tight, but it was with in spec. I have since completed 30,000km plus.

My Vl turbo done some 100,000km and I set the mains closer to 2 thou and the mains similar I think.....

My first imression was that 2.5 thou sounds rather loose for an RB engine. Remember that NIZPRO run what are considered to be tight clearences, like 1-1.5 for both mains and big ends...

Other than contaminated oil (or surge), detonation and clearence issues bearings are generally issue free.

I totally sympathsize with you.

9krpm Mentor

9krpm

Posted
Posted (edited)

Andrew, you are fairly fast at Mallala and your engine failed at the track. Have you consider other causes especially oil surge with your setup?

What oil pump and oil cooler have you been using? What was your oil temperature when the engine failed?

With the amount of g force you are doing around Mallalla, the Trust baffle insert may not be enough if you have a high flow pump. I think a Trust sump extension kit will help your oil surge

Edited by 9krpm
unique1 Mentor

unique1

Posted
Posted (edited)

i run 2 thou on a 420rwkw rb26, has made over 450rwkw on dyno and no dramas with bearings. Im using acl race series if that matters. Has been running for 8 months with no problems. I got this clearance reccomended to me by a well known rb26 specialist workshop so i trust them 100%

Edited by unique1
Blue32 Experienced

Blue32

Posted
  • Author
Posted
i run 2 thou on a 420rwkw rb26, has made over 450rwkw on dyno and no dramas with bearings. Im using acl race series if that matters. Has been running for 8 months with no problems. I got this clearance reccomended to me by a well known rb26 specialist workshop so i trust them 100%

What oil pump are you running? I am starting to believe I may have had an oil delivery problem.......as well as the large clearances

BezerkR32 Veteran

BezerkR32

Posted
Posted

your clearances are not the problem, but your machine shop should have advised you on what to run. usually run larger clearance when revving engine harder, i agree that you might have starved it. also Castrol WTF. how did you measure these bearing clearances?

What oil pump are you running? I am starting to believe I may have had an oil delivery problem.......as well as the large clearances
unique1 Mentor

unique1

Posted
Posted (edited)
What oil pump are you running? I am starting to believe I may have had an oil delivery problem.......as well as the large clearances

jun high volume oil pump, gets around 27psi at idle and 80psi or so at full rpm when warm, i rev to 8500rpm usually. I also run the same oil as well (castrol edge 10w60)

Edited by unique1

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share
Go to topic listing


  • Similar Content

  • Latest Posts

    • Haggerty
      RB25DE NEO with Haltech ECU

      By Haggerty · Posted

      As far as I can tell I have everything properly set in the Haltech software for engine size, injector data, all sensors seem to be reporting proper numbers.  If I change any injector details it doesnt run right.    Changing the base map is having the biggest change in response, im not sure how people are saying it doesnt really matter.  I'm guessing under normal conditions the ECU is able to self adjust and keep everything smooth.   Right now my best performance is happening by lowering the base map just enough to where the ECU us doing short term cut of about 45% to reach the target Lambda of 14.7.  That way when I start putting load on it still has high enough fuel map to not be so lean.  After 2500 rpm I raised the base map to what would be really rich at no load, but still helps with the lean spots on load.  I figure I don't have much reason to be above 2500rpm with no load.  When watching other videos it seems their target is reached much faster than mine.  Mine takes forever to adjust and reach the target. My next few days will be spent making sure timing is good, it was running fine before doing the ECU and DBW swap, but want to verify.  I'll also probably swap in the new injectors I bought as well as a walbro 255 pump.  
    • AnimalGarage
      spot the stagea

      By AnimalGarage · Posted

      It would be different if the sealant hadn't started to peel up with gaps in the glue about ~6cm and bigger in some areas. I would much prefer not having to do the work take them off the car . However, the filler the owner put in the roof rack mount cavities has shrunk and begun to crack on the rail delete panels. I cant trust that to hold off moisture ingress especially where I live. Not only that but I have faded paint on as well as on either side of these panels, so they would need to come off to give the roofline a proper respray. My goal is to get in there and put a healthy amount of epoxy instead of panel filler/bog and potentially skin with carbon fiber. I have 2 spare rolls from an old motorcycle fairing project from a few years back and I think it'd be a nice touch on a black stag.  I've seen some threads where people replace their roof rack delete with a welded in sheet metal part. But has anyone re-worked the roof rails themselves? It seems like there is a lot of volume there to add in some threads and maybe a keyway for a quick(er) release roof rack system. Not afraid to mill something out if I have to. It would be cool to have a cross bar only setup. That way I can keep the sleek roofline that would accept a couple bolts to gain back that extra utility  3D print some snazzy covers to hide the threaded section to be thorough and keep things covered when not using the rack. 
    • GTSBoy
      R34 Handbrake light saying ON and intermittently flashing

      By GTSBoy · Posted

      Probably not. A workshop grade scantool is my go to for proper Consult interrogation. Any workshop grade tool should do it. Just go to a workshop.
    • GabsReDeal
      R32 GTS (RB20DE) Injectors Replacement

      By GabsReDeal · Posted

      In my head it does make sense to be a fuel problem since that is what I touched when cleaning the system. When I was testing with the fuel pressure gauge, the pressure was constantly 2.5 bar with the FPR vacuum removed. When stalling, the pressure was going up to 3.0 bar (which is how it should be on ignition).
    • Duncan
      R34 Handbrake light saying ON and intermittently flashing

      By Duncan · Posted

      ECUtalk pages don't mention they support the ABS computer (consult port has more than one CAN), so you might just need a different scan tool. But, I would expect ABS is a different light to the brake warning/handbrake light, do you see an ABS light come on for a few seconds when you turn the key from ACC to IGN? But since you said: I'd have a look at the ABS sensors in the rear hubs to make sure they are not damaged, disconnected etc.
×
×
  • Create New...