RB25 Head On A RB30 Block, How Hard?

[lkrrepz]

Ive Herd Of People Putting RB25 Heads On RB30 Blocks. How Hard Is This?
I No It Ill Be Better, RB25 Being A DOHC,
Is There Much Cost Invold? Is It Plug And Play?
Anyone Know Cheerz Guyz

 

[Pub247]

you have to change the pistons to fit head on due the the multivalve setup of the twin cam heads but otherwise it bolts up fine

 

[mastadd]

i stole this info, from classicskylinesaustralia

Tap a hole the block for a timing belt tensioner
Gates make a timing belt to suit
RB25 NA pistons, for decent compression
All the usual block prep when building a fresh motor
Shave the head a tad for more compression
RB25DE Head (from R32-No VCT)
May need some oil restrictors in the head, they can flow too much oil and the head fills up with oil.
Remap an RB20 ECU or Nistune/PowerFC/other aftermarket ECU

Can use a later R33/34 head, you will either need to run an external oil line to run the VCT,
or weld the oil galleries in head and block it off - no VCT though - good thing to have particularly for NA application
RB26 head will work too - no VCT to worry about.
If you want VCT the R34/NEO head is best, gonna be pricey though, and I've never heard of anyone doing it. Should be pretty same same though.

 

[Boonz]

sounds like it would be easier to drop a complete RB25 in??

 

[Nzpure]

They do it in NZ heaps to make rb30det & rb30dett which is rb25de head with rb30e bottom end or rb26dett head an rb30e bottom end

Rotorua Import Pro Shop R.I.P.S
those guys make a living off building them heaps of info there

 

[Steery]

It is not uncommon at all for this to be done, popular in Skylines and VL Turbos. They do this instead of dropping a RB25DET in generally because they are looking for big power and the RB30 turned twin cam is the best option for this due to the larger displacement.