GTR inlet/throttles on RB25 NEO

[Goddard]

Guys,

This question has been asked before and I have found various answers. I have been looking at a front entry plenum to go with an FMIC to shorten pipework and neaten things up a bit. GTR throttles/inlets seems to go for cheap money compared to a GReddy inlet for example. I have seen pictures of them fitted to various RB20/25 engines but nothing specific to the NEO engine.

Best info I have found is here,

rb26dett intake manifold and itb's on a rb20 head: RB20 / RB25 / RB26 Forum: Nissan Forums / Infiniti Forums - NICOclub

From what I can see the manifold has the same stud arrangement but not the port arrangement on an RB20. I can easily make up an adaptor plate, and more than likely a fuel rail to run the side feed GTT injectors. If anyone has already done this I would be massively grateful for information or pictures. I know a Greddy inlet would be easier, and cutting off and welding the throttle flange onto the side of the standard inlet cheaper. But the Greddy inlet doesn't work very well with the GTT (and is EXPENSIVE), and a modified standard plenum looks like it will give horrendus flow to cylinder 1 and 2. Plus the standard GTT throttle is stupidly big for both arrangements. GTR inlet solves both problems, plus throttle bodies sound ******* sweat.

If anyone has any info at all it would be great. If anyone is interested in an adaptor plate and fuel rail for their own R33 or R34 I'm sure I could work out a group buy.

Cheers!

[Goddard]

Ok so I took the plunge and have bought a spare NEO inlet manifold and a full set of GTR inlet throttles, inlet manifold, air/water cross over pipe, fuel rail, plenum..

I have found a picture of what I'm trying to achieve,





That is an RB25 engine with RB26 covers and RB26 inlet. I'll be getting some covers to go with the inlet too, oh and a top mount eventually

I have found out some interesting things which have convinced me keeping the NEO head is worth it.

1. NEO engine has solid lifters (ala RB26)
2. NEO engine has more aggressive cam profile than RB26
3. NEO engine has the variable cam timing
4. NEO engine has larger valves than RB26
5. NEO engine has top feed injectors (but high impedeance rather than the low impeadance top feed in RB26).

Now I'll await the arrival of the inlets and begin designing/machining ASAP. Without having looked closely it's hard to say, but I'm still in favour of altering the bottom of the NEO inlet to mate the RB26 throttles onto it. This means the VCT solanoid will clear and the inlet will be a perfect match to the head. From what I can see on my engine there is enough of a straight section on the NEO inlet to chop off and weld some flanges too. This does leave me with the issue of getting the GTR air/water balance pipe fitted to give take offs for vaccum. I need to see the internal detail of the NEO "cast in" pipe before I make a choice here. My initial thought is to chop off the NEO balancer and weld in some alu "turrets" where they are on the GTR item, then machine in the O-ring detail.

I'll try to take lots of pictures and put up information on what I find. I want to keep this as simple and stock looking as possible. Wish me luck!

[Squeak]

NEO engine has GTR con rods too

[Goddard]

Yeah forgot that off my list

I'm pretty interested to see the results of this. I'm hoping it will sound bloody awesome. The GTT/GTsT never sound as good as the GTRs, just a bit "fuzzy" or dulled down. I'm hoping the throttle bodies will crispen the sound up and help that RB howl that I love.

Incidently if anyone knows a safe rev limit for a NEO engine on stock internals I would be interesed to know. Standard is 7000rpm, and I have heard that people use 8000rpm fairly regularly. Do GTR's run past 8000, and is it safe to? Obviously without a bigger turbo it's not worth it, but I'm just curious.

[TriniGT]

Hmmmm ............ Subscribed!!!

[Goddard]

I'm glad someones interested!

I'm about to try and do a massive GTT ICE installation guide with lots of pictures and info, feeling like you're talking to yourself isn't exactly good motivation.

[Mendoza]

I'm glad someones interested!

I'm about to try and do a massive GTT ICE installation guide with lots of pictures and info, feeling like you're talking to yourself isn't exactly good motivation.

If you have a nose on my project thread I've got some boot install pics - not a major installation, and not a DIY job - but may gove you some ideas

About to have a protective case fitted over the amp though - to protect from all that camping gear!

[Goddard]

Cheers Mendoza. I did mine around 2 years ago. But my brother has had the pictures on his computer in Edinburgh and I haven't had a chance to get them off him. I was talking about a guide of what to remove from where, where I ran the power wires, which RCA's to use etc etc.

[Big Mark]

It'll certainly look a lot cleaner under bonnet with that conversion.
Will be interesting to see how it comes along

[Goddard]

OK,

I have got the NEO bottom half of the inlet and the GTR inlet now. (thanks to GTMike and DaveW).

On first glance it seems that my original idea of using the neo inlet chopped about with flanges on to fit the throttles onto will not work. As you can see in the pictures, the runners don't come out straight. This is done to keep the inlet runners the same length.

So the plan now is to get both flanges CMM'd to get the hole positions and the port designs on the computer. At first glance the ports look the same, or close enough, which is handy and makes the adaptor plate a lot easier to make. As for the injectors moving further back, looking at the angle it seems this really will make feck all difference to how they spray. From this information I will get an adaptor water cut out of 2014Alu, machine in the bolt holes myself, and finish off the port matching be hand.

The last thing then would be to modify the inlet manifold so it clears the VCT solanoid. I think it is just the bolt that will catch as there really isn't that much difference between the two, and I was expecting there to be a lot.

I'm not sure if anyone can help me with a few questions that I have, but I need to know where all the gubbins should go underneath the plenum. I have the workshop manual to plow through, but if anyone has a quick reference I would appreciate that. Also, where does the BOV go on GTR's? I want to keep the standard recirc (GTT or GTR), but I'm not sure where it goes on the GTR. And finally, do the GTR injectors have the same fitment as GTT ones? I know people have used GTR rails on GTT's but I can't tell at first glance if the manifold side the the same. I can cope with different lengths, but it might be easier to use GTR injectors, which then I would need to know if the GTT Power FC can be set to run low impeadance injectors?

Any help is greatly recieved and most appreciated!!

The standard NEO inlet showing runner differences. At no point are they the same height bar at the start!


The difference between the NEO inlet and the GTR manifold. Stud holes are in the wrong place, but the ports look identical.


Closer view of the GTR port showing the individual throttle behind


Finger test on NEO port and GTR port


Comparison of the water elbow on GTR and GTT




The GTR manifold



The individual throttles


The plenum chamber



The under side of manifold with IACV - (pipe madness)


internal plenum chamber showing the blend from wall to runner


The layout

[Goddard]

The whole chibang




Thanks for looking!

[Squeak]

Good luck with it all, hopefully comes together nicely ..if not easily

[Goddard]

Cheers squeak, I don't expect this to be that easy, but I think the benefit will be worth it. Plus it's pretty rare, and might be a UK first?

[simon]

You can buy an adaptor plate that lets the GTR throttle body mate up to the RB25 head, it was one of the options that I looked into for my engine but discard bfor acouple of reasons, one being cost, it was cheaper to buy a greddy/RIPS manifold and a single TB is easier to map that a multi TB.

Interesting work though

Simon

[Goddard]

Cost so far is £245. I anticipate being able to get an adaptor plate made very cheaply. Mainly because I can do the CAD and machining myself, and getting a profile water jet from flat plate is cheap too (as long as you have done the CAD). I would have thought further costs being about £50 in total, maybe up to £100.

£345 - You can't buy a Greddy inlet for twice that usually. Plus they're not really made for a GTT and don't work properly. Multi throttles are no harder to map than a single throttle either. If anything they're easier.

I just like being a little different, so if no one else does this so be it