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RB26 rods in RB25?

DETurbine

By DETurbine,
in Engines & Forced Induction

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DETurbine Enthusiast

DETurbine

Posted
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I am in the process of rebuilding my RB25DET motor and just wanted to make sure before I purchase these rods. Can you use RB26 rods with the in a RB25DET with the stock RB25 crank and RB25 forged pistons?. Should I get RB25 or RB26 forged pistons?.....also what conrod bearings should I use?....RB25 or RB26's?

I almost 90% sure that there will be no problem with this, just wanted to double check perfore I do it.

Help would be greatly appreachated,

Zach

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GTRgeoff Grand Master

GTRgeoff

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Big ends use SR20, Mains from RB30 for the ACL (I used Race heat treated @ 140 AUD for the lot) but they are narrower than standard. Still a decent bearing though.

Cameron, did the RB26 pistons give a noticeable reduction in compression? The rods are the same length (I use them in my 25) but I understand they have a significantly shorter pin to deck distance. Is the crank a different length? Too early in the morning to think....

DETurbine Enthusiast

DETurbine

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Big ends use SR20, Mains from RB30 for the ACL (I used Race heat treated @ 140 AUD for the lot) but they are narrower than standard. Still a decent bearing though.

 

Cameron, did the RB26 pistons give a noticeable reduction in compression? The rods are the same length (I use them in my 25) but I understand they have a significantly shorter pin to deck distance. Is the crank a different length? Too early in the morning to think....

I see that ACL has the mains for the RB25DET, just the rods that they do not have. So you can use the SR's conrod bearings for the RB25?

GTRgeoff Grand Master

GTRgeoff

Posted
Posted
I see that ACL has the mains for the RB25DET, just the rods that they do not have. So you can use the SR's conrod bearings for the RB25?
That's great news. Might be that extra width for RB25/26 that is the only thing lacking in RB30.

Ash, do you mean bearings or rods?

Duncan Grand Master

Duncan

Posted
Posted

hang on....I just did a heap of reseach on this one and....like Geoff said....

SR20/RB25/RB26 big end bearings are all identical. ACL have always made SR20 ones but they now packaged in 6s for RBs.

RB30 main bearings are the same size as the 26 main bearings (and presumably 25 as well)...except that they are slightly narrower. Will report back in 100,000klm if they were OK lol

I paid under $50 for all the bearings, so Nissan can shove the extra $250 they wanted for them....I did get a special price but I'm sure even full retail would be under $100 for the 2 sets.

*edit* sorry DETturbine I didn't realise you were from USA.....There was a problem with the ACL catalogue, the mains were listed incorrectly. ACL only make RB30 bearings which I used but are not identical to RB26. I understand all RB26 and RB25 bearings are the same.

cameron Mentor

cameron

Posted
Posted
Cameron, did the RB26 pistons give a noticeable reduction in compression? The rods are the same length (I use them in my 25) but I understand they have a significantly shorter pin to deck distance. Is the crank a different length? Too early in the morning to think....

I spose you could say so, it runs high boost fine (25psi) so its deffienlty been lowered also its harder to tell what the exact compression is because of the 1.8mm tomei head gasket. - lower compression again. Another thing that come's into play is the head was warped a bit so they shaved a couple of mm off. These piston's are arias, same top as the standard cast piston's so their not slugs and they idle fine the the morning after cold start. When the engine finished being put together the reconditioner said it had shit loads of compression ? - So i'm a bit :confused:

It's got really good drivability, response wise, for such a large turbo - 780hp Garrett on it, So the compression can't be that low other wise it would be turbo lag central.

It is deffiently lower than standard.

If you looking for a forged piston i'd recommend arias. - Tryed and proven :)

:(

Jun

Duncan Grand Master

Duncan

Posted
Posted
Thanks allot guys for the research and information. So for my RB25DET with RB26 rods I should use the RB30E main bearings and SR rod bearings?

Also I am guessing that when you guys say "big end" you mean rod bearings right?

Yes yes and yes.

But remember as I said before Rb30 bearings fit fine but are slighty narrower.

Main reason I went for them is they are 10% of nissan price :D

DETurbine Enthusiast

DETurbine

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Yes yes and yes.

But remember as I said before Rb30 bearings fit fine but are slighty narrower.  

Main reason I went for them is they are 10% of nissan price :(

I am going to be putting some power to this motor and don't want to risk anything. Do you think that these RB30 mains will be fine?....last thing I would want to do is spin a bearing. Which should I get...ACL RB30 or Nissan OEM RB25DET bearings for my RB25?

Also I just looked up in ACL's catalogue and they have the RB30E and the RB30ET....I am guessing that the main bearing are the exact same on the two...did I guess right?

Thanks for the help.

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