Jump to content
SAU Community

Recommended Posts

Hey guys,

After many hours scouring the interweb on everything for a R32 into RB25 conversion I have found a site with some very useful information.

As most of us know the RB20 and RB25 ecu pinouts is the same except for the Injector 4 and 6 pins. This site is saying that all you need to do is use the RB20 Engine Loom, swap the two injector wires over, and the plugs for the injectors and then you pretty much just plug the RB25 ECU in and your pretty much good to go.

All that would be left is the VCT which by the looks of the wiring schematic for the RB25 would just need the plug from a RB25 loom and wire the 2 wires in.

Can anyone confirm if this would work? I have been thinking about it long and hard and cant find any reason it wouldnt seeings the pinouts are basically the same.

If it does then it would make one hell of an easy conversion, as there would be no need to splice looms and everything would plug straight in.

I have heard of people using the RB20 loom and ECU, but not the RB20 Loom and Rb25 ECU...

Any input appreciated :)

Here is the site:

http://bc240.com/ind...hp?showtopic=12

And heres the DIY from the site:

Well, there seems to be a certain amount of confusing regarding wiring when doing the RB20 -> RB25 swap.

I read quite a few conflicting things in my search for accurate information, and at the end of the day i just looked over the wiring diagrams, and plugs on the harness, and used little bits of information i read.

So with that, i'm going to post everything you need to do (which is really not much at all). swapping from rb20 to 25 is about the easiest wiring swap you could possibly do. This makes swapping a SR20 into a 240sx look like rocket science.

We will be using the RB20 harness, as its 100x easier, and has no downsides.

You will need:

-Complete RB20 harness including injector sub harness

-RB25 injector sub harness.

- (optional) a plug that will fit onto the VVT solenoid, and some wire.

1) Take the injector sub harness off the RB25. This is the one with the plugs for the sidefeed injectors.

2) Cut all the plugs off, leaving enough wire to solder them onto the rb20 harness.

3) cut off all the top feed plugs on the RB20 harness. 3 are on the sub harness, and 3 are on the main harness.

4) Solder the sidefeed injector plugs onto the RB20 harness and sub harness.

5) You must swap the wires for injectors 4 & 6. Doing this at the ECU is the easiest Just cut pin 112 & 114 and cross them and resolder.

If you have an afermarket ecu (such as in the case of this install), and you can configure your outputs, you can do this in software. In our case we used an AEM EMS... its nice because it supports the RB20, 25, and 26 with one unit.

6) If you want your VVT to work, you must get a hold of the right connector for the VVT solenoid. If you have an rb25 harness, thats easy just take it from there, if not take a trip up to the wreakers and snag one off some random nissan that will work.

Then just solder 2 wires to it, plug it into the solenoid, and wire it up into the ecu. We didnt hook it up, so i'm not sure on the exact wiring. I do know pin 113 is a trigger for the VVT. It would be easy to figure out with a wiring schematic. If you need help with this, post a schematic that includes the VVT solenoid on it, and i'll tell you how to wire it.

7) Your done. Make sure you use an RB25 ecu or calibration.

Yeh there are a lot of people running rb25s with rb20 looms and ecus as the rb20 ecus are easy to reprogram.

I'm interested to hear if people can think running the rb25 with the rb20 loom but the rb25 ecu would work as the wiring looms are basically the same. Which would mean no need to splice the looms

Use rb20 computer and loom with a nistune and it is even easier.

this. you just lose a little bit of low to mid range power from not having the VCT. if you use a z32 ecu though you can keep the VCT. just need to do a little bit of splicing.

Then it's not really any easier. I was just thinking If someone was to do a conversion it would be easy if you only had to swap over a couple wires and your running. Then you could do the nistune on the rb20 later down the track. I think a lot of people find the hardest part of this conversion the wiring

um how is that not easier you don't change ANYTHING on the ecu side, you don't even change a 'couple of wires' they ALL stay the same lol.

The msd switch or eboost is seperate, you just run 2 wires to the relay, 2 to power and 1 to RPM input off the ECU.

It doesn't get any easier than that haha

  • 3 years later...
  • 4 years later...

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now


  • Similar Content

  • Latest Posts

    • Yeah I suspect even if you hold airmass per cycle/cylinder constant if you get too far away from stock you're still going to have problems running the factory tune within the bounds of the factory load scale. Cams, different displacement/rod ratio, etc. I'm just lucky that the GTIII-SS with wastegate boost + CA compliance cats is pretty much equivalent to stock turbos. When I have actual space I can finally get it tuned and modify the fuel system for flex fuel to 100% handle any detonation concerns when cranking the boost to whatever those dinky turbos can put out.
    • I would say no, why, because my daughter, who also lives in Goulburn, hasn't recommended us going there Pity, as we miss all the German joints around in Sydney, actually, the restaurants are the only thing I really miss about Sydney, and a special mention to Ishibanboshi at Bondi Junction, their Kara-age Don is heart cloggingly deliciousness (always added a special boiled egg...or 2) 😋 
    • Does that German restaurant still exist in the old place out the NW end of Goulburn? When I say "out the NW end of"...I am really being vague. It was 1997 when I was last there, and the only point of reference I can recall is that it was on the opposite side of the main drag from the big merino. And when I say "opposite side of the main drag", I don't mean "on the main drag". It was either a couple of streets back from there, or might have even been out in the sticks a bit further. Was an old farm building or mill or somesuch. And when I say "the big merino" I might actually be thinking of a completely different part of town, because I just looked on maps and the big bugger is not where I remembered him to be! The food was good, consisting largely of various German mystery-meat sausage/loaf things and kartofflen.
    • So while the second sentence is completely correct and the whole point of the conversation, the first sentence bears consideration. If this bloke is just hoping to throw big turbos on and drive it around, because there are no helpful facilities at all in his tropical paradise** then he likely has zero chance of even knowing what the TP is on the last column in the stock maps, let alone know whether the ECU is operating anywhere near it or past it. So the point is very very moot. And, per what I said before, at stock boost on those turbos, you may well be off the end of the map. **I'm just back from Vanuatu, so I know exactly what small Pacific nations can be like wrt paradise without requisite facilities. But it's not even that simple. I put a high flow on my car and had to drive it around with a proper tune because of the lack of opportunity*** to put the bigger AFM and injectors into it to allow it to be tuned. I had to turn the boost down to less than I had before, and back off the boost controller's ramp, because it was exploring parts of the map that it didn't drive in before, and really couldn't access for tuning on the dyno either, and so was pinging. It was still well within the last column, because when I first**** set up the Nistune on the Neo I rescaled all axes of the maps to give some more space to explore. ***Family dyno was broken ****This was 13 years ago, and the TIM thing wasn't a thing then and so TP would definitely grow when pushing past the stock tune's limits.
    • Yep, this bit another local owner. I caught it before putting the transmission back into the car, what I noticed was the pressure plate fingers weren't flat and even. It's more obvious with the pull style clutch because the throwout bearing ring was visibly not flat once everything is put together. Nismo should really update their instructions to call out this specific detail. I'm not even sure the clutch as-shipped orients everything properly.
×
×
  • Create New...