Rb26 Inlet Manifold And Adaptation To Rb25 Heads .

[Swiper the Fox]

So you going with a Greddy? Make sure you put on a decen TB when you do it

these guys make good stuff: http://www.throttlebodies.com.au/

rubbish...

these are more like it.

http://www.hypertune.net/index.php?option=...0&Itemid=83

[dano4127]

so if you order a hypertune TB do they make it to suit the plenum or do you get the same shape to suit a hypertune plenum?

TBA will make it to suit the type of plenum and they are far from rubbish

If I was buying a hypertune plenum the choice is easy but if not I would be going to TBA

[Kaido_RR]

I did get RIPS to E mail me pics of his modified RB25 inner manifold section with the RB26 TB's and plenum bolted to an engine and it looks the part .

Rob mentioned that they don't use the air bypass on their engines and I've asked for details but not gotten a reply . I gather he means the cold start heated extra air bypass valve and I'm not sure why they wouldn't use it .

Can anyone familiar with R33 RB25 and R33 RB26 inlet manifolds add anything about this ?

Also for the 20th time can anyone confirm if an R33 GTR's IAC solenoid is electrically compatible with an R33GTS25T (S2) loom and PFC .

Cheers A .

hey discopotator03 i am running an rb26 plenum on my 25 using the blitz kit. im using gtr fuel rail + injectors. i had to wire in the resistor pack for the injectors. I was able to run the rb25 IAC, the blitz kit came with an adoptor to run it but in the end it wasn't needed.

the AAC value problem was abit of a head f**k in the beginning but what we did was replace the std ACC box with a tube with a number of fitting on it and just connect all the hoses to that.

everything work fine and im running pfc and std loom.

I can tell you that this isn't a easy job, i ended up taking the motor out as there is just not enough room to be able to fit the plenum on once you put the adoptor plate. as its very close to the firewall.

im running the stock rb25 throttle cable but it is longer, so i ended up looping it around in the cabin and making a custom bracket in the engine bay.

I am running an hks oil cooler kit so i don't have an issue with the oil filter as it is on the relocation kit.

The major issue with the blitz kit is that because of the VCT the gtr plenum won't fit the water outlet hit its. so you can remove the VCT or else what they say to do it cut and remove the water outlet from the rb25 plenum and weld it onto the rb26 plenum i did this and it work fine! the std r33 radiator hose still fit (i think it was alittle to long so we ended up cutting abit off)

also if i remember right one of the coolant lines which is used in the rb25 plenum (connects to the throttle body) is not used in the gtr plenum i can't remember what we did with those hoses we might have just loop them together or block them off

Edited October 27, 2009 by Kaido_RR

[Swiper the Fox]

so if you order a hypertune TB do they make it to suit the plenum or do you get the same shape to suit a hypertune plenum?

TBA will make it to suit the type of plenum and they are far from rubbish

If I was buying a hypertune plenum the choice is easy but if not I would be going to TBA

Its based on the bolt hole centres...Hypertune TB's suit most plenums including GReddy (90mm)

TBA TB's are/were garbage...basic low end product...had some bad experiences with them years ago, maybe they have picked up their game.

[dano4127]

[Mr GTS4]

does anyone have any pics of the airbox and aac/iac's all connected??

[Mr GTS4]

anyone?

[Kaido_RR]

does anyone have any pics of the airbox and aac/iac's all connected??

i can get some pics for you 2morrow,

[RBceffy25]

For those running itb's without AAC/IAC where do you get vac for brake booster and MAP sensor?

[Nic19]

Hey guys I'm doing this conversion ATM with rb25 runners cut off. Couple of questions, what's the valve under the plenum that is part of the pipe that bolts to the plenum? Also how Do i go about running idle control. And as above does brake booster get vac from the gtr plenum chamber? Will that smaller fitting give me accurate boost and vac reading for guage?

[Nic19]

I've been reading up about doing this. Seems a lot of the Honda guys run a vacuum manifold running a vacuum line from each runner to a tank then run everything that needs vacuum from this vacuum tank/manifold. Seems like a good way of doing it. Anyone else got ideas on how to run it all properlly.

Just wanna know what else runs on vacuum

Fuel pressure reg

Brake booster

Boost gauge

????

[B-rice]

Thread revival anyone know where the injectors will spray with the adapter plates also without them using the cut and weld method. Im trying to think of what would be the best method to do this conversion

[XRATED]

... honestly it's hardly worth the effort.

[B-rice]

Lol its doesnt seem too hard with the cut and weld method. I keep the same injectors and water hose. Just have to work out how to get the Idle control valve. And from what ive worked out its cheaper than a plazmaman.

[GTSBoy]

And just as useless.

[XRATED]

Lol its doesnt seem too hard with the cut and weld method. I keep the same injectors and water hose. Just have to work out how to get the Idle control valve. And from what ive worked out its cheaper than a plazmaman.

LOL your dreaming if you think it's easy... The runners don't line up correctly, nothing fits nicely.

IAC is the easiest part of it.

Even if you could do it yourself, it's not. Plus it's not a quick solution.

,,, don't let me talk you out of it. I've just been there.

GL

Justin

PS what are you hoping to achieve?

[B-rice]

I had a look at Nokumens results when he did it using the adapter plates. The runners not lining up is because theyre not ported properly. Ive seen a smooth finish however i have not done it am willing to do it.

If i do it like the picture above ive already eliminated the fitting part of the plenum to the head.An adapter plate can be made to fit the TPS sensor. The only thing that i could think of being hard (time consuming) would be probably linking up all the water lines properly. I have an oil cooler and relocation kit so there should be clearance on that side.

Im after throttle response, plus its a cheap OEM method for having a front facing plenum. Then again im not being strong headed and saying its do-able im just trying to gather as much information as i can before I give up.Modifying cars is not always easy.

[XRATED]

... just buy a plazmaman or hyper tune. I know it looks like it's the more expensive option, but it won't be.

Oil cooler relo normally takes up more room then stock set up especially above the mounting block (where you will need the room for rb26 IAC).

As for the picture above, if I took that picture to my fabricator.... $600-800 at minimum just in time and flange. That's plus buying the lower half manifold, tb's, probably a rebuild on the tb's, plenum, throttle brackets, adapting the r34 tb, linkages, joining manifold, ballance manifold (that may well foul on your neo designed fuel rail), IAC block, IAC motor, hose work etc...

Then you have to make up a new throttle cable, depending how long you make the runners you will foul on the VCT solinoid.

New intake/cooler pipe work, BOV mounts etc

List goes on.

[B-rice]

Fair enough.

I should have mentioned that i already have a fuel rail, injectors etc, If i were to change to a plazmaman or hypertune i would still need new cooler pipe, bov. The VCT solenoid will not foul because im cutting the runners of an RB25. Welding them to plates that will be used to bolt on the RB26 plenum.

I can fabricate that myself and port match the inside for a smooth blend. I have seen a few plenum going for around the $200-$600 mark. The only thing that would stop me from doing this is the hose work and IAC as you mentioned. Ive heard some do without IAC if they have a standalone ECU but i havent gathered enough information for it. Throttle cable can be cut to length and crimped with a steel wire crimp. All this can easily be done under $800.

But I guess it comes down to doing it if i could get a mock up plenum (which is impossible) would be definetely keen on trying this.

[Sammit]

not meaning to revive an old thread but if anyone is after an adaptor for doing this Otaku Garage now sell them.
https://www.otakugarage.com.au/product/rb26-intake-manifold-adaptor-rb25-rb20/