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Discussion Starter #1
Hi everyone, new to the forums.
I have an R34 GT with an RB25de which I suspect is a NEO.
The way that I'm guessing it's a neo is by the valve on the plenum which opens when the throttle is past half way, and that the throttle body is above the injectors followed by a Y-pipe into the plenum.

I have big plans for this R34 to get it road legal/track ready.

Fisrt off, I got it cheap because it's an auto.
I had a quick look online, and it seems that rb25det gearboxes have skyrocketed in price - around $2500 - $3500.
I am planning to +t the motor, so will a GTR rb26dett gearbox work on a 25de+t? GTR gearboxes seem to be less than $1000 at the moment.
Also, will the NEO affect the gearbox? The most expensive gearbox was a rb25det neo.

Second, if my car is a NEO, and I want to +t, do I have to use a NEO plenum? this seems to be another part that skyrockets in price - add $700 for the neo parts. Can't i jam the neo on and leave it like that?
 

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As you are converting, use the R33 gearbox, clutch and propshaft, will fit and is alot cheaper.

You can use the NA manifold, don't worry about that, won't help to put the turbo manifold on as head is also has smaller channels.

Good luck with the project!
 

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gtr box has transfer box as well and unless you cut it off and weld a plate on the box it cant be used and where do you live that it costs $3000 for a gearbox?? and the truth is you will be cheaper in the long run selling the car and buying one that is a turbo as standard and then you should be able to track it straight away
 

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Until you are 110% certain of your plans don't split the intake plenum off the head...

The gaskets to rebuild R34 GT non turbo plenums are NOT available!
 

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If you fit a GTST gearbox the prop will not fit! I know this from experience.

I had to take the GTST prop and the GT prop to a local prop makers near me for them to make a hybrid out of the both. Cost me £600 about 3 years ago so about $900 in your money.
Waste of money and waste of time, as said sell your GT and buy a GTT
 

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Discussion Starter #7
Just an update:
I got a few parts like coil packs (spark plugs are on the way), turbo exhaust manifold, GT35 turbo, intercooler etc, downpipe, oil feed and return lines. I will be welding a GT35 turbo flange onto a bent pipe (45 degree) to fit onto the downpipe.
Not too sure about the gearbox. I read that you can take the GTR box and cut off the 4WD parts and use a rb25de or rb25et plate to mount it to the motor. Or I could just run a GTT auto ecu and keep it tiptronic, even though tiptoe is worse than auto. But I want to get as much done as possible as soon as possible so that I only end up paying once for LVVC plates (mod certification).

I did a bit of research and I will end up using the factory plenum (just need more piping) because the neo plenum has the valve, and a lot more piping coming off the intake than the non-NEOs.

It was very hard to get a straight answer about whether it's a neo or not. Some have the engine cover that says NEO Straight Six, some don't (or have lost it), but the way I was 100% sure is that the factory injectors are top-feed. I suspect that the valve on the plenum IS part of the neo-vvti system, assuming it's similar to the 13b Renesis in RX8's in that it lets in more air when more boost is needed.
And since neo is vvti, it just affects the intake side of the motor so exhaust and gearbox from older gens should be sweet.
 

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Discussion Starter #8 (Edited)
where do you live that it costs $3000 for a gearbox??
In NZ. There are heaps of 32's, 33's, 34's (and also G35's), so there is a bit of a demand for turbo parts. Plus they like to add "drift-tax" on top of turbo parts. For a while I was planning on swapping the RB for a VH41de, but +t seems the way to go.
 
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