GTR head on GTS-T block

[paul]

I'm contemplating an RB25DET swap into my 240sx. I'm a big fan of the GTR, however, I think that it may be a little too expensive to buy an RB26DETT plus a RB25DET transmission. Not to mention issues w/ relocating the turbo. As we all know, the secret to an engine's power is in the head, which brings me to my question.

Who know's anything about putting a RB26DETT head on a RB25DET block? How much would it cost? How hard is it to do, if it'll even work at all.

[Redline240]

it would probaly cost more, not to mention the down time. Its been done but there's a lot of custom work and it isn't really worth it. The RB25 flows good, the RB26 may flow slightly better but it doesn't warrent all the $$$ and time. Oh and i know that both Dauntt and Night will sell the RB26 with the RB25 transmission. So then it's just a matter of getting a new manifold and a single turbo and it should fit just as easy as the RB25. It is still much more costly than a RB25 swap though...

[FAST-DATSUN]

Why go to all that trouble?? Just put the GReddy or other intake on the RB25.

Mack@McKinney Motorsports

[Siddhartha]

The rb26 and rb25 heads apparently flow the same, the rb26 just has ITBs (Individual Throttle Bodies), so it has better response. Go with Mack's idea.

[paul]

Well I'm not so much worried about the throttle body, that's easy enough to swap. I've heard that the GTR has a special head design, that instead of being simply a concave dome, that it has some sort of hex design, which for some odd reason gives it more power. I don't know why that would be true, nor if its even true.

Does anyone have the facts?

[93RPS13]

where can you get ITB for the RB25?

[McAdam]

If your gonna do that, put the RB26 head on the australian RB30ET block, then youd have a RB30DETT, that'd be pretty toquey. it'd probably shut those supra guys up too! lol I know the 25 head on the 30 block is fiarly common down under.

McAdam

[dreamsOfSkylines]

If your gonna do that, put the RB26 head on the australian RB30ET block, then youd have a RB30DETT, that'd be pretty toquey. it'd probably shut those supra guys up too! lol I know the 25 head on the 30 block is fiarly common down under.

McAdam

Considering how high the the RB25 already sits in the 240 engine bay, its probably not a good idea to use a taller engine (rb30).

[YamaOni]

The RB26 head bolts are larger so you would have to use the 25 bolts but then you are left with A gap around the bolt on the head side. Pay a machine shop to resize the holes in the block and use the 26 bolts. Did this help?

[Nurv]

not a bad idea but why go through the trouble? At a time i was contemplating going that route but changed my mind. For the money why not just get your rb25 head machined? post & polish, cam gears, springs, retainers, cams, etc.. the benfits would be much better.

having a built head would give you some more power versus a stock head. you would be swapping the RB motor for performance upgrades, not STOCK ones. just my .02

[paul]

yeah, I've thought about that, just making the rb25 head better. Would that be as good as the gtr head?