r32gts-t with rb20 maybe to be rb25

[mickb]

Hey fellas,

I'm seriously thinking of buying my mates rb25 with lots of work done to it and removing my rb20 out of r32 manual gts-t and has anyone done this before and was it a prick of a thing to do or was it straight in? Apparently if i keep my r32 gearbox in my car with a rb25 it wont work cause of some shaft that is too big on my gearbox but if i use his gearbox which is series 2 r33 box it will be fine? What do u ppl reckon all comments and tips needed,

Thanks Mike

[R31Nismoid]

i had an R32/HR31 gearbox bolted to the back of my RB25.

only recently put an RB25 box in behind the RB25 motor.

[CerealKiller]

RB25's in R32 GTS-t's have been done over and over again. Searching would be good.

But yes it's pretty much a straight bolt in. Only real issue is the wiring loom.

[Memph]

i had an R32/HR31 gearbox bolted to the back of my RB25.

only recently put an RB25 box in behind the RB25 motor.

notice much difference with the rb25 box?

im still running the rb20 box behind the rb25 in my r32

with the price of gearboxes these days i was thinking i will probably just replace it with another rb20 box if this one dies.

seems to be going strong though...

i figured as long as i dont put some comp slicks or something on the back then it shouldnt be too bad... dunno

hows yours?

[Tizzle]

I did the conversion but i never had the 20 box behind the rb25 so i cant really say what the diff is however on the whole i strongly recommend conversion. Mod plates in qld are cheap as chips to get to. One question i have that i dont feel has been answered in previous discussions, of all the people that have done this conversion what have you done with your diff? eg. keep 20, replace with 25, strengthen rebuild of 20??? After about 3 months of solid driving and a night out at willowbank 1/4 mile mine is starting to slowly slip which my heavy duty clutch isnt a huge fan of and i want to get it sorted. Should I get strong rebuild of 20 (ive heard good things) or go the 25 swap?? keep in mind it was originally non turbo (4 stud)

[R31Nismoid]

notice much difference with the rb25 box?

im still running the rb20 box behind the rb25 in my r32

the gearstick sits about 5cm higher.

thats the only difference.

My RB20 box wasnt stuffed. It just got the death whine about it.

So i upgraded before it died rather than afterwards.

[blind_elk]

I did this conversion on a GTS4. The RB25DET drops straight in and the gearbox bolts straight up onto the engine.

Next step is to fit a 4.08 diff set to replace the stock 4.375 - RB25DET just has too much torque for the current ratios.

[predator]

Should I get strong rebuild of 20 (ive heard good things) or go the 25 swap?? keep in mind it was originally non turbo (4 stud)

diff stength I've heard is quite similar.. in fact the R32 clutch based diff one may be stronger than the viscous diff on the later R33 (edit: ok, maybe thats not correct). If you have an LSD, it should be the same as the one fitted to the turbo model. Depending on the cost, vs finding another one, I'd get your existing one rebuilt.

[BHDave]

I thought only the32 GTR had a clutch type, gtst still has a viscous

On a side note, i've also done the swap and it is great. Same turbo and i now have full boost at 2800 rather than 4200 Also have an extra 25 kw at the same boost with a shitty home tune on the emanage, though i now have a pfc in it and it feels alot stronger with even more midrange punch.

Retained the rb20 box, retained the rb20 diff (but that was already dying). It's next on the list of replacements.

[mickb]

Sounds like a fullyworked rb25 will most likely going into my r32 ...

thanks fellas for the feedback helped me out heeps!!!

Still will be running the rb20 gearbox for a while though till more cash comes in or it blows.

[MerlinTheHapyPig]

r32 gts-t has a viscous lsd

[Cubes]

RB20 box is still going strong behind the rb30det.

Even though its only making 176rwkw its torque that kills box's not so much outright power.

It does whine and make funny noises though.

First and second are rather loud.

[R31Nismoid]

mine was so loud after 2 months (and 2 drag days) that i could still hear it over my stereo on as high as it goes lol

[[HOTNXR]]

how much are we talking for labour to do the conversion? not including rb25 front cut?

[Waldo]

i was wondering wat is involved with the wiring harness, as i was thinking of doing this soon, i run an ap engineering power fc on my rb20det, will this work on the rb25det, and can you use the same loom.

[Cubes]

What final plans have you got for the rb25det?

If its to head upwards of 300rwkw why not simply grab a R32 RB25DE, slap a set of forged pistons in it and be done with it.

The PowerFC will run fine on the r32 rb25de, afterall, thats exactly what I have done with the only difference being I slapped a rb30 block underneath the rb25 head.

The reason I say to go forged pistons is the N/A blocks don't run piston oil squirters.

The only issue that may exist is the emissions side of things as you will be obviously using an aftermarket ecu, that obviously doesn't bother you though.

It will still run on the rb20det ecu, simply throw an R33 wastegate actuator to limit boost to 6-7psi. 6-7psi is on the limit of the rb20det's ecu fuel cut once you are running the much better flowing rb25 head.

Edited September 4, 2005 by Cubes

[predator]

you rb30 pusher you..

or slap in a perfectly good rb25 bolted together.. loom, etc. Nothing to worry about drilling blocks, speaking to engine builders, etc. Good for a nice 230-250rwkw with revability. If it blows, you have all the required parts ready to go for rb30 later on..

i run an ap engineering power fc on my rb20det, will this work on the rb25det, and can you use the same loom.

rb20det doesnt run VCT, rb25det runs VCT (edit: oops).. you would have to disable the VCT via playing with the engine and dick around... spoils the point of the drop in approach.

I can think of quite a few parts also that are different between rb25 and rb20 looms that would cause you problems with rb20 loom: cas, ignitor, injectors. But maybe its possible.

Edited September 4, 2005 by predator

[Cubes]

heheh

I said to run a R32 RB25DE and slap a set of forged pistons in it.

No wiring mods, it really is a simple drop in bolt turbo manifold up, connect up inlet piping start and drive away on the stock ecu, providing you don't dial in more than 6-7psi.

Its static compression is an issue at 10:1 or there abouts, another reason for the forged pistons or any aftermarket piston.

No pushing rb30 here

Edited September 4, 2005 by Cubes

[blind_elk]

rb20det doesnt run VVT, rb25det runs vvt.. you would have to disable the vvt via playing with the engine and dick around... spoils the point of the drop in approach.

I can think of quite a few parts also that are different between rb25 and rb20 looms that would cause you problems with rb20 loom: cas, ignitor, injectors. But maybe its possible.

<{POST_SNAPBACK}>

Only later model RB25DETs run VVT. You can simply add in the wiring for the VVT solenoid. This is the advice I was given AFTER I had wired a whole new loom into my RB25DET -> (R32) GTS4 conversion.

I think there are other threads that suggest you simply swap over the RB20 sensors into the RB25, and everything works OK. Although I was running a RB25 CAS on my RB20, and it seemed to run OK.

[Cubes]

Its only the rb25de's from the R32's that don't run the vct. All R33 motors (apart from rb26) run the VCT.

You can't simply add the VCT wiring and be done with it as the r33 rb25det ecu pin out is different. It has a few extra little bits plus a different arrangement. Allthough not a major drama, its easy enough to swap a few pins around.

I've checked out ecu pin outs in the engine manuals. If only it was so easy.

Edited September 4, 2005 by Cubes