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Rb25/26

tommyb

By tommyb,
in Engines & Forced Induction

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tommyb Collaborator

tommyb

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hi guys just wondering iam wanting to rebuild my rb25 just wondering if this will work and what will need to be done to the block.

i want to use rb26 crank to stroke it

then do i need to use 26 pistons and rods or can i use 25 ones

thanks for any help

iam wanting to run a to4z turbo

i was think of using jun internals

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tommyb Collaborator

tommyb

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Whats your budget dude?

If you use the RB26 crank, rods i think the RB25 pistons.

Someone will confirm as a lot have done it.

I just used the RB25 crank/26 rod/25 piston

it is going into a stagea so i want about 300kw

so i can just use a forged 26 crank rods and pistons

what the deck height will the pistons go to high

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tommyb Collaborator

tommyb

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26 rods and crank and pistons will do it. Same deck height and rod length remember.

25 pistons on 26 rod and crank would be sitting proud of the block at TDC

so BD Dave i can just 26 crank and rods and pistons and i wont have to do anything to the block or

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Stronzo Collaborator

Stronzo

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26 crank has longer stroke, rods are equal (in size, but 26`s are stronger), pistons are different. block height is the same, head cc is almoust th same (25 a bit smaller)

26 or aftermarket rods is a must as 25 rods are weak.

26 crank + 25 pistons will have CR too high or what BHDave said.

The best option is 26 crank+rods+pistons in 25 block. i do the same thing for myself now.

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BHDave Grand Master

BHDave

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You have to check that there's sufficient clearance in the block for the longer throw crank and the big ends of the rods, so maybe a bit of machining there (some one will have to confirm as i haven't dummied one up to check). As you'd probably put in new pistons anyway it's just a matter of machining the bore to suit the new pistons (assuming .5 oversize).

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