To Go Itb's Or Not Worth It? Read On

[Simon-S14]

so anyway my neo 25 is pretty well spot on in terms of power, response and torque. I did want to change the stock over the top of the motor style manifold for the sake of tidying up the engine bay and so forth. i DONT want to go with a cheap shit copy manifold. I would get a greddy manifold but at around 700 odd for a new one i was thinking why not go with GTR ITB's and plenumn. whats needed to make them fit and would it be a total waste of time and money?

looking at changing the diff back to a 4.1 so will need a tad more midrange torque and power to make up for the ratio change from 4.3. this might be one way of doing it?

fwiw a plazmaman manifold is out the question.. they are HUGE and IMO overpriced.

[The Dan]

Ask Rhinorebel what he thinks of his setup.

[R31Nismoid]

You need an adaptor plate made up to have the ITB/plenum go on i believe.

Not the simplest job, but certainly possible.

Blitz used to make an adaptor... I believe they stopped doing it

The adaptor was overpriced too lol, but then it was a one-of-a-kind make

[wlspn]

Am looking at going this setup myself, although on R33 RB25, not Neo.

Rather than a Blitz style adaptor I am leaning more toward welding a plate to the standard RB25 runners which the GTR throttle-bodies can then be bolted to. This way original injectors, idle control, etc can all be kept.

Also the injectors are kept exactly where they were designed to be, etc.

RIPS NZ can do the whole job for somewhere around $600 or look at designing/doing it yourself (I am)

[Simon-S14]

yeah most likely will look at designing my own set up either making an adaptor plate or something you mentioned. pics and more info are welcome!

[R31Nismoid]

If its only 600NZD currently, you'd be hard pressed to beat locally with time/effort it given how poor their dollar is at the moment

[wlspn]

Sorry, think its closer to $900NZD. Was referring to $AUD at the time I converted the price (3-4 months ago)...

[Kaido_RR]

so anyway my neo 25 is pretty well spot on in terms of power, response and torque. I did want to change the stock over the top of the motor style manifold for the sake of tidying up the engine bay and so forth. i DONT want to go with a cheap shit copy manifold. I would get a greddy manifold but at around 700 odd for a new one i was thinking why not go with GTR ITB's and plenumn. whats needed to make them fit and would it be a total waste of time and money?

looking at changing the diff back to a 4.1 so will need a tad more midrange torque and power to make up for the ratio change from 4.3. this might be one way of doing it?

fwiw a plazmaman manifold is out the question.. they are HUGE and IMO overpriced.

Ran Rb26 plenum with blitz adaptor kit on my rb25 (non-neo) and recommend it. Its not a easy job and my advice would be to take the engine out as it makes the job 100x easier.

What needs to be done to make it fit:

1: Adaptor Plates

2: Remove Radiator water outlet on Rb26 Plenum and weld on the rb25 plenum radiator water outlet

3: R33 S1 throttle positioning sensors will bolt onto the rb26 plenum

4: GTR throttle cable (gts-t throttle cable is too long, i just loop mine inside the cabin but its easier to just get a gtr cable)

5: Make a bracket to hold the throttle cable

6: There is a big air box on the underside of the gtr plenum

What we did was remove the box and made up a pipe section which allow all the vacuum lines to be connected.

This is needed as the std rb25 filter will hit the gtr plenum

7: You will need to use the gtr fuel rail, which means you need to wire in the plugs for the GTR injectors and also wire in the gtr resistor pack for the injectors

I think that is about it, if i remember anything else i post up and if you have any question just ask

Edit: Also the gains, i pick up around 200-300rpm, before the swap i had full boost around 3300rpm after plenum install was getting full boost around 3000-3100rpm.

Will try and find some photos of the conversation

Edited April 12, 2011 by Kaido_RR

[XRATED]

I've been looking at this for a while and all the people I've talked to everyones been happy with the results, no one has gone back or changed to a greddy/style.

At the end of the day it's not a huge gain for the work involved- but it is a gain.

Some guys have used 10mm alloy plate to make up the adapter- I was going to use something alot thicker to create a longer distance between the tb and ports for slightly better low end torque.. it all depends on the clearance to the strut tower too.

I say go for it and post up the results as a pure, before-after.

Cheers

Justin

[rob82]

If your hoping to gain actual transient response within the usable rpm range of that turbo(4000-7000rpm) then it will help. However I wouldn't jeopardize runner length unless you dont mind loosing mid range power (1000-55000rpm) and mid rpm spool rate.

[Kaido_RR]

If your hoping to gain actual transient response within the usable rpm range of that turbo(4000-7000rpm) then it will help. However I wouldn't jeopardize runner length unless you dont mind loosing mid range power (1000-55000rpm) and mid rpm spool rate.

i didn't lose anything from doing the swap.

As XRATED mention it is not the easies swap and does cost abit, however i found no negatives to the swap other than the cost/time it takes to do the swap.

Plus it makes the engine bay look so much neater

Edited April 12, 2011 by Kaido_RR

[Simon-S14]

If its only 600NZD currently, you'd be hard pressed to beat locally with time/effort it given how poor their dollar is at the moment

can do a CAD drawing of the adaptor easy enough.. once this is done i have a machinist who can work off the file. shouldnt cost any where near as much as buying a made kit.. there is however trial and error. I would like to see some pics of plates used to get a rough idea what to expect atm.

thanks for the pics posted so far guys... loads of info here already

[rob82]

i didn't lose anything from doing the swap.

As XRATED mention it is not the easies swap and does cost abit, however i found no negatives to the swap other than the cost/time it takes to do the swap.

Plus it makes the engine bay look so much neater

Have you got dyno graphs to prove back to back runs with nothing but the intake manifold change. Talk to some of the RB25 guys that go to the plazman manifold - they all experience some bottom end loss due the runner length halving.

[R31Nismoid]

Oh look if you can play around in CAD then ye - of course. but its a time/effort thing as you are no doubt well aware

[Simon-S14]

well i did some searching and it seems a member did it all on a neo motor with no adaptor plate... sweet as! looks like its pretty straight forward then.

as per here http://www.skylinesaustralia.com/forums/topic/247435-mating-rb26dett-throttle-plenum-on-rb25det-neo-head/page__view__findpost__p__4606691

[R31Nismoid]

Have you got dyno graphs to prove back to back runs with nothing but the intake manifold change. Talk to some of the RB25 guys that go to the plazman manifold - they all experience some bottom end loss due the runner length halving.

Roy saw this issue when he changed to Plazman/6boost manifold combo. (check his RB02 build thread for more detailed info)

Which part was to blame - hard to say of course - either way upgrading was a costly exercise for less...

[Simon-S14]

plazman maniflolds are HUUUGE thats for sure... they really only suit VL's and their large engine bays. i had the misfortune of working on a 34 with one fitted and you couldnt change the oil filter from the top thats for sure. or the sides for that matter.

[PM-R33]

Have you got dyno graphs to prove back to back runs with nothing but the intake manifold change. Talk to some of the RB25 guys that go to the plazman manifold - they all experience some bottom end loss due the runner length halving.

Ummm do you mean a Greddy manifold? Plazmaman doesn't touch the runners.

While getting to the oil filter is harder, it aint that big of a deal. The only thing that made mine harder is the extra braided lines teeing into the fuel lines for the nitrous being in the way.

[XRATED]

Personally I wouldn't be welding onto the head... Tig is a 'hot' process. There are just so many finely machined clearances to be buggered around with by adding that much heat.

An adapter plate can be made as easily as a slice of alloy plate, the two types of head gaskets and some basic hand tools.

And if it all goes tits up you can put it back to stock.

Cheers

Justin

[Kaido_RR]

Have you got dyno graphs to prove back to back runs with nothing but the intake manifold change. Talk to some of the RB25 guys that go to the plazman manifold - they all experience some bottom end loss due the runner length halving.

i will have to check to see if i still have my dyno print outs.

Nothing else was change when i did the plenum swap if i remember right, i think i even ran the same boost on the retune. Interesting that when the retune was done, the whole tune had to be wipe and start again as everything was out with the gtr plenum on.

For me no bottom end loss, the car was more responsive everywhere.

The blitz plate are only 100mm thick maybe less. i had the plate which connects to the head slightly ported to suit the head ports.

The kit is now on a friends car, however it is having turbo issue so has not had a proper retune. Will be interesting to see the result he get as it is running an identical setup to what i had (even has my old hks pro s turbo)

Edit: just for info the photo i posted was with my newer setup which was running a 3037S however the result were not as good as my engine was dieing, very low compression and eating oil

Edited April 12, 2011 by Kaido_RR