No Choice, Have To Change Engines, Rb20 To 25 Please Help

[Ryno]

I did the RB25DET conversion on my R32 about 6 years ago...

If I were to go back in time and do it all again, I'd put a RB26DETT in instead. Heaps easier option with respect to the wiring, and a better platform to start with.

Although the engine is initially more expensive, it will already come with a front mount, front facing plenum etc. So that will be money you don't need to spend later down the track.

With the R33 engine, you will lose the HICAS (no problem for me as I'd already removed it all) but I still don't have the aircon step-up or speed variable power steering working. I've just learned to live without it.

By the way I'm still using the RB20DET gear box, and it has been holding up fine with 250 rwkw. So work out how much power you will be after, before deciding on replacing the gearbox.

[Rolls]

With the R33 engine, you will lose the HICAS (no problem for me as I'd already removed it all) but I still don't have the aircon step-up or speed variable power steering working. I've just learned to live without it.

All good points except this one, if you use the rb20 ecu then you get to keep all of this stuff.

[Ryno]

All good points except this one, if you use the rb20 ecu then you get to keep all of this stuff.

True, however I wanted to replace the computer with a Power FC and I also didn't want to loose the variable valve timing. I realise there once was the AP Engineering Power FC for the RB20DET, but this was big bucks at the time.

[335]

I did the RB25DET conversion on my R32 about 6 years ago...

If I were to go back in time and do it all again, I'd put a RB26DETT in instead. Heaps easier option with respect to the wiring, and a better platform to start with.

Although the engine is initially more expensive, it will already come with a front mount, front facing plenum etc. So that will be money you don't need to spend later down the track.

With the R33 engine, you will lose the HICAS (no problem for me as I'd already removed it all) but I still don't have the aircon step-up or speed variable power steering working. I've just learned to live without it.

By the way I'm still using the RB20DET gear box, and it has been holding up fine with 250 rwkw. So work out how much power you will be after, before deciding on replacing the gearbox.

Would the RB26 be too much power for the GTS-T to handle? What would I have to do to make sure the car performs well with it?

The wiring matches up?

[Rolls]

Would the RB26 be too much power for the GTS-T to handle? What would I have to do to make sure the car performs well with it?

The wiring matches up?

Same as any powerful engine, suspension, good grippy tyres etc.

[Ryno]

Would the RB26 be too much power for the GTS-T to handle? What would I have to do to make sure the car performs well with it?

The wiring matches up?

The wiring is much easier, as the engine loom will all plug in to your existing looms. Then later on down the track when you are chasing more power, there are plenty of aftermarket ECU options.

Are you worried about having too much power?? There's no such thing! But in any case, a standard RB26 will work well in a GTSt, then depending on what power level you are after later on down the track (ie. greater than 250 rwkw) would dictate whether you need to replace the gearbox.

[335]

The wiring is much easier, as the engine loom will all plug in to your existing looms. Then later on down the track when you are chasing more power, there are plenty of aftermarket ECU options.

Are you worried about having too much power?? There's no such thing! But in any case, a standard RB26 will work well in a GTSt, then depending on what power level you are after later on down the track (ie. greater than 250 rwkw) would dictate whether you need to replace the gearbox.

So that easy to put in a 26? What about the slump? I was told that you have to cut it. What is the slump exactly?

[Rolls]

So that easy to put in a 26? What about the slump? I was told that you have to cut it. What is the slump exactly?

lol it is a sump, eg where the oil is stored.

[335]

lol it is a sump, eg where the oil is stored.

Is this hard to do? Is this the only thing that needs to be done to fit a RB 26 into a R32 GTS-T?

[Ryno]

Is this hard to do? Is this the only thing that needs to be done to fit a RB 26 into a R32 GTS-T?

Not as hard as sorting out the wiring drama with the RB25...

The drama with the sump is because of the AWD system, so you have two options:

Remove the front wheel drive system from the RB26 sump, and then weld up the holes, or:

Replace the RB26 sump, with one from a RB25, though I believe you will also have to modify the oil pickups, as they are not the same as the RB25.

[335]

Not as hard as sorting out the wiring drama with the RB25...

The drama with the sump is because of the AWD system, so you have two options:

Remove the front wheel drive system from the RB26 sump, and then weld up the holes, or:

Replace the RB26 sump, with one from a RB25, though I believe you will also have to modify the oil pickups, as they are not the same as the RB25.

Ok

So if I can find a decent price RB26, than it will be easier to connect everything.

With the RB 20 wiring with the 25 engine, besides having to have a switch for the VCT, is there anything else that will have to be rewired differently?

Can I use the RB20 computer and use a EManage　instead of the Nistune?

[XRATED]

So it sounds like the rb 20 loom is the better way to go. Only the engine, and transmission will change? So Hicas wont work after the engine change?

How much does Nistune cost?

If I go the 25 computer and loom, I will need what other sensors and parts?

If you go that way you will need all the engine sensors a full loom and ecu, then you will have to patch that loom into the chassis.

Would the RB26 be too much power for the GTS-T to handle? What would I have to do to make sure the car performs well with it?

The wiring matches up?

A 26 in a 32gts-t is one of my favorite combo's.... it's not easy to achieve though. Especially in jap land where labour/fabrication is expensive.

Ok

So if I can find a decent price RB26, than it will be easier to connect everything.

With the RB 20 wiring with the 25 engine, besides having to have a switch for the VCT, is there anything else that will have to be rewired differently?

Can I use the RB20 computer and use a EManage　instead of the Nistune?

I wouldn't bother with a 26 in your situation, you don't have the knowledge or skills to do it yourself and it's going to be very expensive to get somone to do it for you.

The rb25 swap can be all but plug and play... Get yourself a low km series 1 rb25. Swap over the rb20 sensors to the rb25, drop the 25 in and plug the loom in. You can do the rest with the e-manage (not a great option) or other ecu.

Remove the CAS, AFM, TPS, temp sensors, pressure sensors/switches, ignitor module/coil packs/coil pack loom, etc from the rb20 and install it all onto the rb25. Remove the injector loom from the rb20, cut the injector plugs off and solder on the rb25 injector plugs onto the rb25 loom. The rb20 AC pump, alternator and power steering pump should all bolt up to the rb25 too.... so the wiring stays the same for tem too.

Just do what you would do if you were going to replace the rb20 with another 'undressed' rb20 long block. The ecu won't know you magically added 500cc.

As for the hicas, remove the hicas ecu/pump/lines etc and install a hicas lock bar.... hicas was a bad idea from the start, so ditch it.

[Rolls]

The coilpacks and afm from a series 1 rb25 are the same as the rb20 items as far as I know.

[335]

If you go that way you will need all the engine sensors a full loom and ecu, then you will have to patch that loom into the chassis.

A 26 in a 32gts-t is one of my favorite combo's.... it's not easy to achieve though. Especially in jap land where labour/fabrication is expensive.

I wouldn't bother with a 26 in your situation, you don't have the knowledge or skills to do it yourself and it's going to be very expensive to get somone to do it for you.

The rb25 swap can be all but plug and play... Get yourself a low km series 1 rb25. Swap over the rb20 sensors to the rb25, drop the 25 in and plug the loom in. You can do the rest with the e-manage (not a great option) or other ecu.

Remove the CAS, AFM, TPS, temp sensors, pressure sensors/switches, ignitor module/coil packs/coil pack loom, etc from the rb20 and install it all onto the rb25. Remove the injector loom from the rb20, cut the injector plugs off and solder on the rb25 injector plugs onto the rb25 loom. The rb20 AC pump, alternator and power steering pump should all bolt up to the rb25 too.... so the wiring stays the same for tem too.

Just do what you would do if you were going to replace the rb20 with another 'undressed' rb20 long block. The ecu won't know you magically added 500cc.

As for the hicas, remove the hicas ecu/pump/lines etc and install a hicas lock bar.... hicas was a bad idea from the start, so ditch it.

What is the CAS and TPS? So the engine will operate fine with the stock computer? What is suggested to use the VCT with? To control it?

What about the fuel pump, should I change that to a bigger one?

[Rolls]

No the computer will need to be remapped to suit the rb25 engine, a nistune is the best option but an epprom remap with the standard rb25 map will do if you haven't done any modifications.

VCT can be controlled via a MSD switch, an eboost street boost controller or any other auxiliary window output controller.

[335]

No the computer will need to be remapped to suit the rb25 engine, a nistune is the best option but an epprom remap with the standard rb25 map will do if you haven't done any modifications.

VCT can be controlled via a MSD switch, an eboost street boost controller or any other auxiliary window output controller.

So what is a MSD switch? An eboost street boost controller is any boost controller? Auxiliary window output controller is what?

I am sorry, I am learning here.

[Rolls]

MSD make a window switch, eg it enables an output during a window of revs. The standard rb25 computer enables the VCT between 1500 and 4500 rpm I think, so the switch takes the RPM input and when the rpm is between that window it turns on the output, the output then enables the VCT solenoid.

An eboost street is a boost controller but it also has a window output controller built into it which can be used for this purpose, there however are various other solutions out there, you will have to do some research and talk to whoever you are planning this conversion with as it doesn't sound like you will be the one wiring it all up anyway.

[XRATED]

What is the CAS and TPS? So the engine will operate fine with the stock computer? What is suggested to use the VCT with? To control it?

What about the fuel pump, should I change that to a bigger one?

CAS is Crank Angle Sensor and TPS is Throttle Position Sensor.

The engine won't operate correctly with the stock ecu... you will need to re-tune the stock ecu or use a piggy back etc.

I use a simple rpm window switch sold by JEGS in the US to controll the VCT.

Change the fuel pump.... by now it's at least 15 years old if it's the origional. You should be able to find a suitable drop in replacment from nismo etc... or even a low km GTR pump.

If you do go ahead with the swap, double whatever budget you work out... trust me. Also, before you install the new engine get it checked (you don't want to go through all this just to find out it's a dud) and replace ALL the service items- belts, timing belt/idler bearing, clutch etc... I'd also advise replacing the water pump and oil pump for a N1 pump with a crank collar if your going to modify the new engine.

The rb20 gearbox won't put up with alot of torque and abuse... go with the rb25 box.

Cheers

Justin

[Rolls]

Walbro GS342 (I think that is the model) is drop in, quiet and fairly cheap replacement. Doesn't flow as much as a bosch 044 but is far quieter and fine for stock power levels.

[335]

Walbro GS342 (I think that is the model) is drop in, quiet and fairly cheap replacement. Doesn't flow as much as a bosch 044 but is far quieter and fine for stock power levels.

You are supposed to replace the clutch too?

How is the Nismo fuel pump?