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Is Rb26 Internals Compatible With Rb25

humz

By humz,
in R Series (R30, R31, R32, R33, R34)

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humz Proficient

humz

Posted
Posted

hi im in the process of rebuilding my engine and am undecided as to what path to go down. ive heard differant information about this (25+26internals) but i want some concrete info!

QUESTION: can you put a rb26 crank, rb26, rods and rb26 pistions into a standard rb25 block? and increase the capacity???

PROBLEM: this longer stroke will obviously smash the valves with a standard head gasket, BUT how big of a gasket or spacer plate do you need to prevent this???

PROBLEM: whats teh diff between the rb26 pistons and 25 pistons?

OVERALL: is it worth it??

thanx peeps

MR331307 Experienced

MR331307

Posted
Posted

Should of asked this is Performance section

anyways

You can run the Crank Rods and pistons.

There is no Stroke difference only Piston sizing by .5m from what i remember.The RB26 top and Rb25 tops are different and i would say if your rebuilding it you miles well stick with

Rb26 crank

Rb26 Rods (they are Stronger)

Rb25 pistons (just oversized 20-40 thou)

What are you using the motor for and what are your future plans

humz Proficient

humz

Posted
  • Author
Posted

thnx for quick reply.

i might start another thread in performance section aswell.

engine is for some responsive street work, looking at 400rwhp reliable, definately forged set up with pistons and maybe rods.

the reason why i ask this, my first plan was to build my 3.0litre with twin cam, but theres some good priced pistions and rods for sale ere and im thining of gettin em.

will doing the 25/26internals increase capacity?

will using 26 pistons not work with the 25 head?

MR331307 Experienced

MR331307

Posted
Posted
thnx for quick reply.

i might start another thread in performance section aswell.

engine is for some responsive street work, looking at 400rwhp reliable, definately forged set up with pistons and maybe rods.

the reason why i ask this, my first plan was to build my 3.0litre with twin cam, but theres some good priced pistions and rods for sale ere and im thining of gettin em.

will doing the 25/26internals increase capacity?

will using 26 pistons not work with the 25 head?

I have a couple of questions for you

1) what were you useing the car for exactly (Road + Drift,Drag,Circuit)

2) what sort of money you want to spend

3) who is doing the work

4) where you from

humz Proficient

humz

Posted
  • Author
Posted

1) hard road use

2) ive got 3grand to spend on engine parts, (already got 2vvt r33 heads, 2 rb25blocks, 1rb30 s2 block n loads other parts) so dont need to buy that, already got huge T04e, ecu, ect... engine parts which will include, pistons, bottom end rebuilt kit, head gasket, head work(if money allows then bigger valves n Hbeam rods)

3) ill be doin a bit of work to save labor cost, and my mate diesel fitter is gona do most of it.

4)im in perth, was gona get maybe applied engineering to fit the head, after doing minor port polish and re-con with new valve spring (and bigger valves if money allows)

B0oStEr Mentor

B0oStEr

Posted
Posted

Rb26 internals are a straight swap into an rb25 motor.

The bores are identical.

The rods are the same dimensions but rb26 rods are stronger.

The piston pins are closer to the top of the rb26 piston to compensate for the longer stroke so there is no problem with valve clearance and the resulting compression ratio of about 8.5:1 is ideal for most mild applications.

By the time you buy good rod bolts and prep the stock rb26 rods you may as well buy eagle rods.

To do this rebuild justice you will need a lot more than $3000

humz Proficient

humz

Posted
  • Author
Posted (edited)

is it worth it tho? has anyone done it and what have they found, pros and cons? or do u know of anyone whose done it?

or shall i just do the 25/30.?

so you guys r saying there is absolutely no clearance issues with these internals?

i dont see how 3gee will get me half way??? theres a few sets of used forged pistons on sau for bout $700, rods $800 new, gasket $500, bearings, seals ect $400... so far thats about 2.4? and what eva it cost for honing n acid bath ect, ill just need a bit more for head work i think. and labour is a favour from a mate. its obviously not a 10grand rebuild coz thats not realistic for ME just yet and probably not necessary for MY 100% street use, just a bit better than standard, strong an reliable.

what cost have i missed?

cheerz guys

Edited by humz
R31Nismoid Grand Master

R31Nismoid

Posted
Posted

The crank will need machining + collar etc... if you dont have the R33 crank already

Realistiaclly you wanna be putting then N1 pump

It almost works out cheaper to just get a new crank if you have the R32 crank ... so $110, but nissan dont have any at the moment :D

R31Nismoid Grand Master

R31Nismoid

Posted
Posted

Basically yeah, by the time you fart around with the R32 GTR one, the R33 one comes in cost-wise very close, and its new :D

Depends what you want, a 25/30 could be better, it might not.

I havent done the conversion myself, but i've had old RB25 & recently my RB26 built...

And i've pondered/gone over these details myself many many times :no:

For me, i was thinking about a 25/30 and a 26/30 aswell, but i ended up opting for the displacement i had to begin with based on what i want, and the characteristics i wanted the car to have

  • 4 years later...
boz_soljah Mentor

boz_soljah

Posted
Posted

what type of machining will the 32 gtr crank need, is there a particular measurment or anything.... ive got one that i wana use in my 25, also got 26 h-beam rods and getin a set of 26 forged pistons...

iplen Mentor

iplen

Posted
Posted

what type of machining will the 32 gtr crank need, is there a particular measurment or anything.... ive got one that i wana use in my 25, also got 26 h-beam rods and getin a set of 26 forged pistons...

Sure hope it's enough to reach 88mph

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