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Alright, this will be my next projec tonce I get my S15 RB26DETT up and running but as for now I am already acquiring some parts, namely the damaged RB26DETT engine. I have done a bit of searching and people are saying that you need to machine the headstud holes and retap, some others also said you can use the RB25DE headstuds and they work proper, can someone clarify. What else needs to be done, was thinking about a new headgasket and a baffle and the usual RB26 headwork for oiling problems. Can anyone advise me who has done it as I am thinking along this direction. If the damaged engine has a good block and crank then my swap will be an RB26 but not sure until it is scrapped, guy just told me it was a spun bearing and the crank needs polishing but no one can know unless it is scrapped. Let me know what is needed as I am thinking along these lines.

Good question that , non VVT head on VVT block - if the 26 block is RS .

I suppose you could look for an R32 RB25DE block and fit it with piston oil squirters and good internals .

I think American mobs can sell you non metric threaded fasteners but you have to get the block drilled/threaded and not sure about the heads bolt holes .

Ask SK , cheers A .

  • 3 weeks later...

What exactly do you want to know? The head will bolt on using rb25 head bolts, but as i said the compression ratio will be low due to the difference in cylinder volume. You really aren't gaining anything by using a neo bottom end, as a non-neo bottom end will end up with a more appropriate comp ratio. You could get a set of non-neo forged pistons and fit them to the neo bottom end, that will fix the comp issue.

Okay are you sure that using the RB25 headbolts I can bolt on the head? The reason I am using the Neo bottom end is because the RB26 engine that I am getting has bottom end damage and that I already have an RB25DET Neo engine in my GTT. Maybe the RB25 forged pistons may be an option I can look at, thanks. I just want to confirm that the headstuds from the RB25 can work on the RB26 head without worries, can you confirm firsthand?

I wanted the individual throttles and also the intake mani run on the side for shorter coldside piping, and also maybe do a twin turbo setup all at the same time, oh and the wow factor :/. Actually I am getting the RB26 for a good price and getting aftermarket intake manis for the RB25DET Neo is harder and expensive along with the harder to get injectors and then the exhaust manifold. Okay so RB25DE or is it RB25DET headstuds or are they the same, gonna do a search now?

Yes I know but I am getting the entire head for a good price and having the individual throttles is an added bonus as well as the twin turbo setup. Let's not harp on the topic I just want to make sure you can use RB25 headstuds and if so is the RB25DE and DET headstuds the same, I am thinking so. Thanks to all for the input BTW.

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