Using An Rb26dett Power Fc On An Rb20det

[paulr33]

I have done the reverse, using an RB20DET PowerFC to run an RB30/26.

Use one AFM and parrallel up the ECU inputs. The PFC will see 2 X AFMs both reading exactly the same.

Do the same for the lambda sensors.

Use a standard RB26 air temp sensor mounted in the intercooler pipework before the throttle body.

The speedo readings via the commander/datalogit will be inaccurate due to the different diff ratios.

From memory all of the other sensors are the same.

If you use RB26 standard injectors it will start and run straight up.

cheers

Hi Gary,

I'm a little confused. Here you have said use the RB20 PowerFC on an RB26 head which has two airflow meters. The RB20 ECU only has AFM input on its wiring loom/plug (at least off the diagrams anyway). Also on the Hand Controller you would only see AF1 under SENSOR SW / CHECK. So I am confused as to how you would parrallel hook up a pair of airflow meters. Where does the other AFM go?

Or is the RB20 PFC basically the RB26 ECU hacked up to work on the RB20, so under SENSOR SW it has two afm's, two 02 sensors despite on only of each working and returning a value? And the wiring plug on the ECU has the pin for the 2nd airflow meter and if you hook another up, it works and begins reporting a value?

Also confused how it would work out of the box with rb26 injectors, aren't these different impedance to the stocker RB20 ones (which the RB20 PFC would be expecting?)

I am sure there are perfectly good explanations for each, I just don't see see the complete picture, hopefully you can elaborate.

[MattSR]

From what I know, SK is running a single turbo with a single Q45 AFM and single lambda sensor on his engine.

You can use the GT-R injectors as long as you have the GT-R resistor pack installed with them too.

Im sure SK can correct this/elaborate more.

Cheers,

Matt

[Sydneykid]

Hi Gary,

I'm a little confused. Here you have said use the RB20 PowerFC on an RB26 head which has two airflow meters. The RB20 ECU only has AFM input on its wiring loom/plug (at least off the diagrams anyway). Also on the Hand Controller you would only see AF1 under SENSOR SW / CHECK. So I am confused as to how you would parrallel hook up a pair of airflow meters. Where does the other AFM go?

Or is the RB20 PFC basically the RB26 ECU hacked up to work on the RB20, so under SENSOR SW it has two afm's, two 02 sensors despite on only of each working and returning a value? And the wiring plug on the ECU has the pin for the 2nd airflow meter and if you hook another up, it works and begins reporting a value?

Also confused how it would work out of the box with rb26 injectors, aren't these different impedance to the stocker RB20 ones (which the RB20 PFC would be expecting?)

I am sure there are perfectly good explanations for each, I just don't see see the complete picture, hopefully you can elaborate.

MattSR covered it pretty well.

Single turbo

Single Q45 AFM

Single slow and narrow lambda sensor

Plus a fast and wide lambda sensor for tuning via the TechEdge Af ratio meter and Datalogit

Plus an GReddy exhaust gas temperature sensor and gauge also connected to the Datalogit

(The exhaust from the turbine looks like a porcupine)

RB26 injectors with resistor pack = high impedance

(I am actually using high impedance injectors, so no need for resister pack)

Hope that answered the questions

cheers

[paulr33]

thanks for that, it did help. what if you want to run two afm's?

[MattSR]

you can run a rb25pfc on a rb20 IF you swap injector triggers for clys 5 and 6 and run larger than stock (rb20 stock) injectors.

tested it out on a buddies car and will prove difinitvely when i get my car back together.

Ahh ok

Edited March 15, 2006 by MattSR

[Denver]

can also go the way of the rb20 loom on a 26, or in my case, an rb25 loom running the 26 with an rb20 ecu with a rom board in it...

depending on application/car etc

[predator]

I thought the whole reason you couldn't run the rb25 powerfc on an rb20 was the different ignition system more than anything else?

If you used the rb25 ignitor, cas and the rb25 ecu then i'd imagine you'd be pretty close.

[Sydneykid]

thanks for that, it did help. what if you want to run two afm's?

Simply parrallel them up, the ECU will only see one voltage signal. It's just like the RB26 ECU, which internally averages the 2 X AFM voltages and maps fuel and ignition accordingly.

cheers

[AD4M]

how about using a D Jetro version from a gtr on a 20?

predator i believe the series 1 33 gtst runs the same ignition setup as the 32 does??

[predator]

predator i believe the series 1 33 gtst runs the same ignition setup as the 32 does??

I've tried an RB25 ignition module on my rb20 .. wouldn't crank?? Same coil packs, etc but how it fires must be slightly different.

lol.. lots of ?? in here

[carl h]

I've tried an RB25 ignition module on my rb20 .. wouldn't crank?? Same coil packs, etc but how it fires must be slightly different.

lol.. lots of ?? in here

the ignitor modules are the same internaly, but the pinouts are diffrent between a rb20 and a rb25 ignitor.

i run a z32/rb25det ignitor on my rb20 and all that i had to do is a little rewiring but it works a treat.

basicly the inputs and outputs are swapped around on the ignitor, so you have to rewire the plugs, doesnt take much time and can be useful if you cant source out a rb20 one.

heres a pic of mine:

and a link of my writeup and theroy of why it works.

http://forums.nicoclub.com/zerothread?id=116502

[Cubes]

Carl... You said $180ish. Is that in AUD? I'm assuming USD.

My ignitor has began cracking open (looks quite strange) around the little ridge that runs around the edge of the top plastic. .

[carl h]

um they usualy sell for 180$ usd but i get a nice discount at my dealer (cost + 10%) so it was only 150 or so for me.

but yeah it works, and since rb's didnt come stateside gotta get creative.

[d0p3y]

So just to clarify; Which would be more advisable? I've got RB20DET, and I'm PFC shopping:

a) AP Engineering PFC for RB20 = $1450

b) Apexi PFC for R33 RB25 = $950

c) Apexi PFC for RB26 = $950

Which would I be best off buying? Is the AP worth the extra $500, or should I just adapt one of the others to my engine (if so, which is better?)

Regards,

Ryan

[MattSR]

My feeling (I have never done it BTW) is to try a R33 RB25 PFC - it has the same number of airflow and EGO sensors.. from what I can see on the wiring diagrams, just swap the injector triggers around, and run the correct impedance injectors.

[Denver]

My feeling (I have never done it BTW) is to try a R33 RB25 PFC - it has the same number of airflow and EGO sensors.. from what I can see on the wiring diagrams, just swap the injector triggers around, and run the correct impedance injectors.

Injectors you will find are the same impedance <high>, GT-R injectors are low impedance and require a ballast resistor, the rb25 PFC should work without needing to rewire anything, should be able to just plug it in, set the options, and start the car, if i can run an rb26, using a complete rb25 loom inc coils packs and coil loom, from an rb20 ecu, without touching the wiring, it should not be a hassle..

You'll probably need to spec a series 1 rb25 pfc, as i think the series 2 does change some of the wiring, i could be wrong however

Edited March 22, 2006 by Denver

[GTR-Ben]

Simply parrallel them up, the ECU will only see one voltage signal. It's just like the RB26 ECU, which internally averages the 2 X AFM voltages and maps fuel and ignition accordingly.

cheers

So opposite to that.. using my RB26DETT PowerFC, and a single turbo.

Will my single RB20AFM in a 4" pipe with the signal split to the ECU (so it will half what it sees) going to be tunable enough? Or have I got it wrong somewhere..

[kwazza11]

i doubt it would split the signal if you connected them parallel as the AFM signal is just a voltage, so splitting it would mean you effectively get both identical AFM inputs.

so how about the tacho output? is the rb26/rb20 output the same?

this could be an escape from the fcon V i'm locked into with my rb24..

[carl h]

My feeling (I have never done it BTW) is to try a R33 RB25 PFC - it has the same number of airflow and EGO sensors.. from what I can see on the wiring diagrams, just swap the injector triggers around, and run the correct impedance injectors.

the real problem lies within the flow of the injectors not the impedence, since rb25 squirters are 370cc's the pfc expects 370's, not the 270's as standard on a rb20.

if you are planning to upgrade injectors (which on a rb20 should be done anyways) then it doesnt matter, but for those who arnt then its not such a hot idea.

again it will run with the 270's but very poorly due to the pfc expecting larger injectors.

since both the rb25 and rb20 use high imp injectors you may need to use a resistor pack depending on what injectors you end up using, ive got some denso 720's which are low imp so ive a resistor pack to suit.

[GTR-Ben]

i doubt it would split the signal if you connected them parallel as the AFM signal is just a voltage, so splitting it would mean you effectively get both identical AFM inputs.

so how about the tacho output? is the rb26/rb20 output the same?

this could be an escape from the fcon V i'm locked into with my rb24..

With a RB26 ECU it does because it is use to 2 inputs of 1/2 the flow.. It can be complicated to wrap your head around... but a 4" pipe is basically double the stock 3" RB20 AFM surface area..

It runs good.. just hoping it can be tuned ok..

I have seen a single probe post intercooler in a 3" pipe for a GTR.. so may try that one if this is too corse.