Jump to content
SAU Community

Rb25 Rod Bolt Replacement

PM-R33

By PM-R33,
in Engines & Forced Induction

 Share

Recommended Posts

PM-R33 Grand Master

PM-R33

Posted
Posted

Hey just to clear something up. With the main weakpoint of a RB25 appearing to be the factory rod bolts failing when pushed into high power (compared to RB26 factory internals), it is not possible to put a set of aftermarket rod bolts in with the engine in the car through the sump is it? I mean it is possible to do, however it can not be done correctly right?

Had a quick search but didn't find any threads about it.

Cheers

Link to comment
https://www.sau.com.au/forums/topic/293345-rb25-rod-bolt-replacement/
Share on other sites
Cjmartz2k Proficient

Cjmartz2k

Posted
Posted

Answering the question you asked, no, you'll need to pull the motor. Well, at least pull the head when it's time to put the piston/rod assemble back in.

And for the record, while I agree the ringlands are the weak spot on an RB25, I've seen people bend connecting rods with out hurting the piston from simply making to much hp.

PM-R33 Grand Master

PM-R33

Posted
  • Author
Posted

Ahh f**k forgot about the ringlands, very true. So you guys don't think the factory rod bolts in 25's are a weakpoint? What is the most common failure on a RB25 when pushed towards the 500+HP mark? Ringlands and rod bolts no?

Mr. Untouchable Experienced

Mr. Untouchable

Posted
Posted

before I start, i'm am not a engine builder, and this is not straight from the horses mouth, but i know of someone who was seeking advice from racepace about a 25 build and the comment was , stock 25 rods will support up to 400rwkw's, just need to bugger off the stock bolts in favour of arp gear.

but when my my tuner last tuned my car he said he stopped it at 7000 rpm, 17.6 psi (made 318rwkw) due to "rb25 rods being the weakest of rb's"

as for the weekest point in the 25, I doubt you'll get a solid answer. I have personal heard a few different answers.

The way I see it, Don't push it that hard unless your prepared to rebuild it (whenever that time comes) people laugh at me when i tell them i have made 350kw's on my stock 25. but i'm not bloody pulling the motor out unless its dead lol.

PM-R33 Grand Master

PM-R33

Posted
  • Author
Posted

Well im the same, i dont really want to build it unless it goes bang. And if i did build one, id probably do a 3L. I have heard similar things, that RB25 rods aren't that bad. They aren't as good as GTR rods, but aren't usually the main cause to engine failure unless revved hard. I also heard that replacing the stock rod bolts with ARP items helps keep them together and this was a discussion that came up regarding whether you could do it by taking the sump off as it would be a relitively cheap upgrade to aid in keeping it all together. But yeah, i didn't think it could be done. However at the time i forgot about the ringland issues with RB's and if something was going to fail that would probably be it.

How long has your stock bottom end being pushing that power for?

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

    • Kapr
      Boost cut after swap(RB25DET NEO) R34

      By Kapr · Posted

      So stock ECU does not like anything above 10 psi?  That Nistune one is just for "try" if it will be any different, I know it need to be tune for that. I know but YOU may know about these problem but i/we dont. They few little Skylines here let alone people who know anything about tham so that is why iam asking here  
    • Duncan
      V37 Radiator removal

      By Duncan · Posted

      So now we have a radiator with no attachments whatsoever. It lifts up with a particularly tight spot between the drivers side air box mount and the lower radiator outlet, but if you've got this far you will sort that too. This is the lower mounts with the rad out so you can see where the rubber bushes go, it is a straight shot upwards Done! Assembly is the reverse of disassembly, with blood less likely to be shed.
    • Duncan
      V37 Radiator removal

      By Duncan · Posted

      Right, onto the second last trick. The Air Con condenser is mounted to the front of the radiator and stays in the car when the radiator is removed. There are 2x 10mm headed self tappers holding the top of the condenser to the radiator, remove those The bottom of the condenser is attached to the radiator with clips. You need to lift the condenser out of those clips and clear (up, then forward). f**ked if  could work out how to do that last bit with the front bumper on. I hope you can, and you share the trick.  Bumper removal probably deserves its own thread one day once I've recovered the will to live, but basically you need to remove the wheels, front inner guard liners (clips and 10mm headed bolts), the self tapper between the guard and the bumper at the rearmost point of the bumper (same as an R32 that bit), any remaining clips at the top/front of the grill, an absolute bastard design with a plate that holds the top of the bumper above the headlight each side (only 1 bolt which is tricky to get to, but the plate catches 2 places on the bumper and must be removed....carefully!) and push clips between the bumper and guard under the headlight. If you've done all that you will be faced with wiring for the fog lights on both sides and in ADM Q50 RS at least, 4 nasty tight plugs on the driver's side for the ADAS stuff. So, the clips at the bottom look like this on drivers side (looking from the front) And on the passenger side (also from the front), you can see this one is already out Clearance on both of these are super tight; the condenser needs to move up but the upper rad support mount prevents that, and the radiator can't move down far because it is (rubber) mounted. Once you achieve the impossible and drop the condenser off those mounts so it does not stop the rad moving, you are good to go
    • Duncan
      V37 Radiator removal

      By Duncan · Posted

      OK, next the shroud needs to come off and there are a couple of tricks. Firstly, there is a loom from near the passenger side headlight to the fans, coolant temp sensor etc and there is no plug to undo.  In my case I was OK to leave the shroud on top of the engine so I just undid the passenger side fan plug and about 10 of the clips which gave enough free wire to put it aside. The fan plugs were super tight, the trick I used was a small falt screwdriver to push down on the release tab, then a larger flat screwdriver to lever the plug out of the fan unit....be careful with how much force you apply! If you need to remove the shroud altogether for some reason you will have to deal with all the plugs (tight) and clips (brittle)....good luck. I removed all of the clips and replaced them with cable ties that I will just cut next time. Also, in the Red Sport / 400R at least, the intake heat exchanger reservoir hose is bolted to the shroud in 2 places with 10mm headed bolts; so remove them (the hose stays in the car; no need to undo it at the t fittings down at the radiator lower mount. Once you've dealt with the HX hose and the wiring loom, there are 3x 10mm headed self tappers holding the top of the shroud to the radiator; remove those.   The shroud then lifts out of the bottom mounts where it sits on the radiator, up and onto the engine out of the way. Simples
    • Watermouse
      Unpeeling the Orange

      By Watermouse · Posted

      Ok, disregard my “rate them” comment, sorry for my unrealistic input
×
×
  • Create New...