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RB25DET in GTS4 R32 conversion

Jim Boi

By Jim Boi,
in Engines & Forced Induction

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Jim Boi Apprentice

Jim Boi

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RB25DET in GTS4 R32 conversion

Hello all, 

As you can tell I'm new to this forum but have used it as a reference for many years and value the opinion and experience of the posters. 

I have recently purchased an R32 GTS4 and I'd like to swap the engine from a Stagea RB25DET Neo. I have read lots of posts on here and I've saved the pages so I should be able to get over some of the wiring issues. The mechanical side seems long and tedious and messy but as far as I can tell, reasonably straight forward. I have a few questions though:

Which ECU would suit the engine best, I've heard people favouring the RB20 ecu because it can be Nistune'd, Im thinking further down the line I will do this but I'm tempted to just use the ecu that comes with the engine? 

Are there any things to be aware of when doing this conversion, for example different years having different ecu pin outs etc?

Would it be quicker to install an earlier RB25DET (non Neo) to save some headaches later? - Is it an easier/quicker conversion?

I believe (don't quote me) that the full wiring and induction manifold and ecu can be used on the NEO engine, with some minor adjustments to fuel rails and idle control module (IACV) Is this more or less correct? 

 

I have recently restored an american muscle car and carried out a build log, I can start one for this car and upload it once completed as a guide or how to, if that suits or is required. 

Thanks in advance for any guidance. 

 

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Guilt-Toy Grand Master

Guilt-Toy

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You really need to buy a aftermarket ecu for this car.

Adaptronic modular ecu can do the awd and the vct.

I would not bother with the stagea ecu and the hassle you need to get it to run properly.

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KiwiRS4T Grand Master

KiwiRS4T

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Stagea Neo into GTS4 should be fairly straightforward...just have to make sure you use the same diff ratio front and rear. The hard part seems to be finding such an engine.

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jmknights93 Mentor

jmknights93

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1 hour ago, KiwiRS4T said:

Stagea Neo into GTS4 should be fairly straightforward...just have to make sure you use the same diff ratio front and rear. The hard part seems to be finding such an engine.

I have 2 of them at work. S2 RB25 and a RB25 NEO. Both AWD.

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Jim Boi Apprentice

Jim Boi

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Thanks for the replies. I searched about last night and found a guide on putting in the non neo rb25 into an R32 Gtst. Is it similar wiring? 

By the looks of it, it may pay me to keep with the Neo ecu and get that Nistuned later on. 

Ive seen a few front cuts for sale, but in all honesty, I don't want to have to pull and engine out of a front cut - I'd prefer to just get the engine, turbo and loom to the ecu. 

 

 

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jmknights93 Mentor

jmknights93

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29 minutes ago, Jim Boi said:

Ive seen a few front cuts for sale, but in all honesty, I don't want to have to pull and engine out of a front cut - I'd prefer to just get the engine, turbo and loom to the ecu.

As per post above, I have 2 options available. PM me for details.

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GTSBoy Grand Master

GTSBoy

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6 hours ago, Jim Boi said:

By the looks of it, it may pay me to keep with the Neo ecu and get that Nistuned later on. 

 

You will need to Nistune it from the outset.  There are DTC faults that you can't deal with unless you have NIstune.  Missing ABS & TCS are the big ones.  Being able to override the boost sensor errors etc etc, also vital.

Edited by GTSBoy
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GTSBoy Grand Master

GTSBoy

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DTCs are fault codes.  Diagnostic Terminal Codes, or somesuch. The Neo era cars ABS computer talks to the ECU more than the R32 era cars' computers talk to each other, so I'd guess you'd be the same as not having ABS.  Actually making sure that your original ABS keeps working could be a challenge too.

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Jim Boi Apprentice

Jim Boi

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Does the ecu talk to the abs then, I'm guessing there is an abs 'brain' somewhere? I was under the impression that the speed sensors for the abs were tied into the attesa ecu along with the g sensor under the centre console. 

Its look like a bit of a headache to use the neo engine. Perhaps the image of the neo ecu could be copied to the rb20 ecu - is nistune that advanced. 

What about an earlier Rb25det from a stagea, are these suitably strong enough for further tuning. I was biased toward the neo engine as I believed it would be more capable of taking the tuning. 

Again, thanks to all contributors, it's good to hear feedback. 

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GTSBoy Grand Master

GTSBoy

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There's no point in contemplating putting the Neo ECU's image into an RB20 ECU.  For one thing, it's just not possible.  For the another, it's the image/program that is the problem when it comes to expecting communications to/from other CUs in the car (ABS/TCS/ATTESA).  So it's not the type of ECU that matters. If you really wanted to you could run the Neo engine on an RB20 ECU with the RB20 image in there.  All you have to do is sort out the sensor wiring differences and tune it.  But that doesn't gain you anything at all.  You'd only do that if you were running some engine for which you cannot do Nistune into its ECU (like R33 and earlier Stagea engines).  So that also puts paid to your idea of using an earlier Stagea engine.  It wont make it easier, it will actually make it harder, because then you definitely have to use a non-native ECU to run the engine (if you want to tune it).

The Neo ECU is significantly more advanced than the older ECUs and therefore would be the better choice for running the engine.  If you Nistune it, then you obtain the ability to bypass all the DTCs that come up from not having proper communications between the other CUs.  And that's all you need to run the engine properly.

The ATTESA computer and the ABS computer in your car should still run just fine with a different ECU in there.  Look what happens to all the thousands of guys who put aftermarket ECUs into these cars.  The 4WD and brakes don't just suddenly stop working.  A Nistuned R34/Stagea ECU won't be any different.

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KiwiRS4T Grand Master

KiwiRS4T

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On 28/04/2017 at 6:20 PM, Jim Boi said:

 

Its look like a bit of a headache to use the neo engine. Perhaps the image of the neo ecu could be copied to the rb20 ecu - is nistune that advanced. 

 

There is no headache if you use the appropriate ecu - a neo one from a S2 stagea or an R34 one. Try to get the engine, ecu and loom as a set and then  as GTSBoy says Nistune it - it has been done many times before. It doesn't matter whether its out of an auto or manual - it will work fine.

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Jim Boi Apprentice

Jim Boi

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Thanks for the replies. I'll get on it then, neo stagea engine with loom and ecu and then get said ecu nistuned. 

Now I have a starting point, it should be easier to go shopping.. funds depending. 

 

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KiwiRS4T Grand Master

KiwiRS4T

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1 hour ago, dr phil said:

Be wary of the diff ratios - i thought Stagea was 4.08 and gtr/gtst was 4.11. You may want to double check.

Quite right but wear on the tyres can make more difference than .03 in the ratio which is insignifcant.

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