Rb30/25 Using All Rb20 Sensors Etc

[wads66]

hey guys i have a r32 with an rb20 and i want to built an rb30det to put into it i have done a fair bit of research and cant remember seeing anything about doing it this way and was wondering if some one can confirm if this way will or wont work?

What i was thinking was to use an rb25det head on the rb30 block and not run vct then transfer all rb20 sensors over to the rb25/30. I know about the injectors issue but i was planning on getting a manifold to suit the rb25 but use top feed injectors. It was years ago i had both cas side by side but from memory there the same. the air flow metre would be rb20 for start up only then switch to a z32 if everything is running. Will the rb20 ecu run the rb30 just for start up?

anyway its an idea and if any one can inform me of why it will/wont work it would be awsome.

cheers

Edited May 16, 2012 by wads66

[R32Abuser]

Firstly, always do a search...All the information you require has been covered before. If you want to be smart, search more specifically in the "R33 Rb30 Conversion" thread. Read the RB30DOHC guide which is attached to the VERY FIRST POST in the previously mentioned thread. It runs through the basics, and once again, answers your questions in one way or another.

Secondly, decide on what RB25 head you wish to run. If I had my time again, I would run with an RB25 Neo or RB26 head. Both of these run solid lifters and if I remember correctly, will allow you to choose aftermarket cams which have significantly more lift than R32/R33 RB25 DOHC heads. Depending on the cam profile choice, higher lift can (and in most cases will) yield a higher engine power output.

Thirdly, run VCT. Theres no real excuse for not running it other than being lazy. You can even run the RB20 ECU and use a third party boost controller to activate VCT. There's no such thing as too much torque ...even with an RB30DET.

As you said, injector type will depend on the manifold you wish to run. What manifold you use will depend on what head you run. So first things first, decide on your basics then worry about the specifics. Similarly, your CAS item and wiring will depend on the head you choose.

The RB20 ECU unmapped with the RB20 AFM will run the motor for startup and "limping" around purposes only. Since the RB30 is breathing in a significant amount more air for the same RPM (all things being equal), the RB30 will max out the AFM and you will most likely hit "Rich and Retard" very early. Up to you, but for the sake of some dollars, I'd chuck it on the back of a tow truck and let the tuner run it up on the dyno and remap the ECU of your choice (PFC, NIStune, Link, Vipec etc.).

Do some reading of the above thread. You will learn ALOT!

Edited May 16, 2012 by R32Abuser

[wads66]

I have read that thread a heap of times and other on the subject but could never get the answer i was after. I know you have to use the rb25 or rb26 head (weather r32/r33/r34) the issue was can all the rb20 sensors fit/run on the rb25 head and rb30 block.

[R32Abuser]

I have read that thread a heap of times and other on the subject but could never get the answer i was after. I know you have to use the rb25 or rb26 head (weather r32/r33/r34) the issue was can all the rb20 sensors fit/run on the rb25 head and rb30 block.

If you actually read all 350 or so pages, I would be surprised. You obviously missed this post then which took me all of a minute to find after searching...

http://www.skylinesaustralia.com/forums/topic/15420-r33-rb30-conversion/page__st__700__p__685858#entry685858

Hi guys, whilst GTR- Ben is almost right, it is actually the sensors you use on the engine that determine which ECU and loom you use. As an example we have an RB31DET (RB30 at 3.1 litres with an RB26DETT head) that uses an RB20DET Power FC and the original R32 GST loom . What I have done is use all of the sensors off the old RB20DET on the RB31DET. I swapped over the water temp sensors, knock sensors, throttle position sensor, CAS, boost sensor, oil pressure sensor, AFM (we used a Q45 AFM) etc. Plus I used the 565 cc injectors that were in the RB20DET, which were top feed and high impedance to match the Power FC.

I did it this way, rather than use an RB26DETT ECU and loom, because I already had an RB20DET loom and Power FC in the car. So it seemed simpler to swap the sensors and injectors over while both engines were out of the car. Plus I am not very good with looms, I never seem to be able to get them to fit back in the way they should.

If I had an R33GTST I would have done what GTR-BEN suggested and used all the original stuff with the RB30 bottom end.

Hope all that makes sense.

What Sydneykid is saying there is that the car your installing the motor into and the sensors you use will dictate the ECU you need to run.

Where it gets tricky is if you start mixing and matching intakes with different heads, fuel rails etc etc. Things begin to get messy and I've only heard of a specific few which are compatible with one another (e.g. R33 RB25 intake with R34 Neo head). IMHO keep it simple and use the intake from the head you are using and leave it at that.

Also bear in mind, there are exceptions for sensor compatibility. From my understanding, R32 CAS will not work with R34 NEO head (and some R33 later production) for below reasons.

Hey man! Nice to hear from you too. Re OP's question - he asks about R32. According to my info source, R32 uses CAS disk with four standard size slots and two unique width slots for sync purposes. R34 CAS has all unique slots, i.e. no two slots are of the similar width, so rewiring won't help. AFAIK, R33 has their CAS changed at some point of their production period, hence possibility for R33 ECU to work with CAS

(taken of NIStune forums)