Whats Involved In Fitting An Rb26 Head/inlet To An R33 Gts25t ?

[discopotato03]

Righto , it seems that RB26 heads and inlet manifold systems are the best available from the factory so assuming R33 GTST owners like myself can get them what would be involved in applying them to the single turbo R33 and its RB25DET . Actually I'll go one further and say that most would have either a PFC or some other tunable computer to start with .

The problems I can forsee are :

1) Dfferent coolant/oil passages at the front of the block/head .

2) different sized stud holes (larger) in RB26 heads .

3) Fitting issues ie will the 26 IAC stuff fitt in with the 25DET water/oil cooler .

4) If required fitting the RB25DETs single turbo exhaust manifold .

5) Wiring loom mods to connect sensors in places foreign to an R33 GTST .

6) Sensor compatibility .

7) Injectors - all high/low impedance and top feed rather than side feed issues .

8) Water plumbing issues ?

Anyone done this conversion or nutted out the fixes , cheers A .

[sam5709]

i to would also like to know this

[Roy]

Question has to be asked why not then ust throw a complete RB26 in with harness. Less engineering involved and you get the extra 100cc. LOL where do you draw the line with the spend ? hehe thats why i still run a std RB20

[shanef]

roy pose's a very good point.

IMO this is the line where u say its too expensive for the gains. sure putting on the 26 plenum and throttle setup to the 25head is quite expensive, but i reckon the extra work required (as stated in the first post) would be the killer and make it far too expensive, even for the 'backyarders'.

[Adriano]

1-Pretty sure there will be minimal water passage dramas, you may need to tap and grubscrew the oil feed to the VCT. Dont forget to fit oil restrictors.

2-Simple, use rb25 head bolts, the head is located by the dowels

3-The rb26 also uses a water/oil heat exchanger. I would say both the 25 and 26 IAC would be pulse width modulated, so there shouldn't be too many dramas there.

4-Two options here, aftermarket single turbo rb26 manifold, or an adapter plate. I would avoid modding the head. Cheap rb26 staino manifold would be my choice, just brace it and the exhaust. Or a good aftermarket one-your choice

5-TPS isnt too far from the original, IAC will need lengthening, CAS, water temp and injectors are in the same spot. May wish to add wiring for the Air temp sensor. Will need to change injector plugs, and add a resister pack if you want to use the rb26 injectors.

6-You may have to fit rb25 water sensor, as i said not 100% sure about IAC though

7-As said above

8-Water plumbing for the turbo will be very similar betweent the two, a few hoses to nut out, but nothing too complex

[TiTAN]

Roy, except that you only get 70cc more with the RB26 as it has a capacity of 2568cc and the RB25 has a capacity of 2498cc

[NYTSKY]

Righto , it seems that RB26 heads and inlet manifold systems are the best available from the factory so assuming R33 GTST owners like myself can get them what would be involved in applying them to the single turbo R33 and its RB25DET . Actually I'll go one further and say that most would have either a PFC or some other tunable computer to start with .

The problems I can forsee are :

1) Dfferent coolant/oil passages at the front of the block/head .

2) different sized stud holes (larger) in RB26 heads .

3) Fitting issues ie will the 26 IAC stuff fitt in with the 25DET water/oil cooler .

4) If required fitting the RB25DETs single turbo exhaust manifold .

5) Wiring loom mods to connect sensors in places foreign to an R33 GTST .

6) Sensor compatibility .

7) Injectors - all high/low impedance and top feed rather than side feed issues .

8) Water plumbing issues ?

Anyone done this conversion or nutted out the fixes , cheers A .

I think Adz here on the forums has on on his 25,shoot him a PM.