Jump to content
SAU Community

Recommended Posts

Hi all,

I'm new to this forum and I've been on CalaisTurbo and R31skylineclub forums for a while and have had RB30E and RB30ET setups on my R31's I owned. I have now recently purchased an R31 with an RB25DET NEO motor, RB20 box with Extreme racing button clutch, R31 silhouette 3.9 LSD, 3 inch turbo back exhaust, AM front mount cooler, and dual stage boost controller (8psi on low and 13 psi on high). Currently the power I'm getting is 187rwkw @ 8psi and 212kwrw @ 13 psi with the stock R34 GTt ECU, stock injectors and bosch 040 pump

with my current setup my questions are:

*What turbo does the RB25DET Neo have and how much boost can it be wound to?

*How much boost (safely) can I run on the stock internals of an RB25DET Neo with stock ECU & A/M ECU?

*What is the limit on the stock injectors (power/boost)?

*What is the best aftermarket injectors with my setup without changing the fuel rail?

*What is a good suggestion for an aftermarket ECU to run higher boost?

*How much power can my drive line possibly take (RB20 box/extreme racing clutch [rated at 1600 kg's..so I've been told by previous owner], and R31 silhouette 3.9 LSD)?

*I've heard of KKR turbo's being a decent/cheap upgrade; are they reliable and substantial in comparison to power output/price wise on other turbo types?

Sorry I'm still pretty noob with all this :laugh:

What I'm basically after is a high power output....maybe somewhere between 250-300rwkw without having to change internals (if that's even possible) and most of the current setup; yet at the same time be on the safe side. Maybe looking towards upgrading ECU, injectors and Turbo, most likely ECU if anything.

The usage of this car is basically a mixture of street/drag/weekend use. Trying to keep costs at minimum (if that's even possible LOL) and to increase a power output on my setup safely. Any suggestions?

Link to comment
https://www.sau.com.au/forums/topic/251431-rb25det-neo-in-my-r31-questions/
Share on other sites

stock silo lsd's are crap, if it spins double now it wont for much longer once you start using it, a few rings and it'll spinning single, the diff itself will handle the power no worries

I have an R31 with an RB25 Neo.

In no way do I claim to know everything, so - to my knowledge...

*What turbo does the RB25DET Neo have and how much boost can it be wound to?

The turbo has a VG30 style exhaust housing and the compressor wheel is made of a nylon composite material, making it more fragile. Most people say that 10psi is the safe limit.

*How much boost (safely) can I run on the stock internals of an RB25DET Neo with stock ECU & A/M ECU?

The R34 internals are probably a little stronger overall then the R33. They are known to have GT-R RB26 style conrods (mine did when it was pulled apart) which are good for the power level you want. Also has GT-R style shim & bucket solid lifters instead of hydraulics.

The stock ECU has an overboost protection which I think comes in at 12 or 14psi(?), I think it basically richens the hell out of the mixture and retards the timing all the way.

Aftermarket ECU I'm not sure, because I don't know if the R34 motors have the same issue with R33 RB25s where they break piston ringlands. I guess if you're not worried about rebuilding it then wind the boost up and tell us how much psi you had in it when something breaks :P

*What is the limit on the stock injectors (power/boost)?

215rwkw? Don't really know for sure. They're smaller than R33 injectors (R34 are 340cc vs R33 370cc or something like that)

*What is the best aftermarket injectors with my setup without changing the fuel rail?

Nismo 440cc?

*What is a good suggestion for an aftermarket ECU to run higher boost?

Apexi PowerFC is very popular, also the new Vipec range.

*How much power can my drive line possibly take (RB20 box/extreme racing clutch [rated at 1600 kg's..so I've been told by previous owner], and R31 silhouette 3.9 LSD)?

RB20 gearboxes are very similar to series 3 R31 RB30 boxes. With the power you want you'd be better off with an R33 or R34 gearbox. If you did that you'd have to get a custom tailshaft made. Mine is a single piece using a Z32 300ZX twin turbo gearbox yoke and bigger universal joints.

Australian R31 diffs are pretty weak. I drove on mine for about a year with the Neo and the gears inside the diff centre pretty much collapsed. Had that rebuilt to stock Silhouette LSD specs with a Pintara 4.11 crownwheel & pinion and now 2 years later it's groaning and whining like it's the original diff. I don't drift the car, do burnouts or drive like an idiot, it's just weak. The fix is a Kaaz LSD centre. $1500 last time I heard. Have fun trying to break it after that :)

I suppose if you drive like an idiot then fairly quickly you'll have to replace the diff, then either the gearbox or the universal joints.

*I've heard of KKR turbo's being a decent/cheap upgrade; are they reliable and substantial in comparison to power output/price wise on other turbo types?

Have no experience with KKRs. You get what you pay for I guess?

Edited by Bluprint
is yours an rb25?

yer?

the diff's start making lots of noise but they dont break easily, just whine louder and louder.

gearbox all depends on how you drive, can kill it 100kw if your an idiot, but probably a good idea to get a 33 turbo box, 34 is pull type clutch which makes it harder

as for the tailshaft with a 25 box, easiest way is to get a shop to put a vlt/33 yoke on your standard tailshaft, or if you wanna spend a bit more get a custom single piece made up

rb20 box wont last

i killed a perfectly good RB20 box with 270rwkw/RB25, i did about 15 passes, on 225 tyres so it wasnt as if i was launching on sticky rubber.

if you plan to use the power, plan to change the box and you might as well do it while the motor is out

As for Nissan live rear axles I can add a bit .

From memory one of the larger so called luxo barges like 260C or 280C had a Japanese H190 differential and those are reasonably durable - compared to a Borg warner 8. something "Ford Diff" . Damn local content in Nissans of that era .

LSDs are a bit exy though some JDM Nissans had a production plate LSD in them .

If you can find one and are keen enough to fit it the JDM semi trailing arm IRS gets you into a long nose R200 and is a step up from a live rear end but not as good as multi link IRS like R32/33/34s have .

You are at a cross roads here where you can spend a lot and risk painting yourself into a corner with an R31 .

Their limitations are 4 stud hubs (limited bolt on brake options) , macpherson front struts and at best semi trailing arm IRS . They are also heavy cars . The Aus spec interior is a bit plasticy in some peoples opinions .

Now your call but you get a quantam leap (quote SK) in technology going from R30/31 to R32 and beyond and I'd think you could probably find a clean R32 GTST for not too much money in the scheme of things .

You could plonk the RB25 in an R32 which already has 5 stud hubs , far better suspension/brakes/std R200 and is wired and plumbed for an RB twin cam . Add the R33/34 turbo RWD gearbox and have a pretty good package .

I built a Bluebird with the whole DR30 driveline and was not happy with it , I then had a DR30 and was not happy with that either - just added dinosaur steering into a longer better trimed package .

Your call , cheers A .

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

    • Hi, is the HKS  Tower Bar still available ? negotiable ? 🤔
    • From there, it is really just test and assemble. Plug the adapter cables from the unit into the back of the screen, then the other side to the car harness. Don't forget all the other plugs too! Run the cables behind the unit and screw it back into place (4 screws) and you should now have 3 cables to run from the top screen to the android unit. I ran them along the DS of the other AV units in the gap between their backets and the console, and used some corrugated tubing on the sharp edges of the bracket so the wires were safe. Plug the centre console and lower screen in temporarily and turn the car to ACC, the AV should fire up as normal. Hold the back button for 3 sec and Android should appear on the top screen. You need to set the input to Aux for audio (more on that later). I put the unit under the AC duct in the centre console, with the wifi antenna on top of the AC duct near the shifter, the bluetooth antenna on the AC duct under the centre console The GPS unit on top of the DS to AC duct; they all seem to work OK there are are out of the way. Neat cable routing is a pain. For the drive recorder I mounted it near the rear view mirror and run the cable in the headlining, across the a pillar and then down the inside of the a pillar seal to the DS lower dash. From there it goes across and to one USB input for the unit. The second USB input is attached to the ECUtec OBD dongle and the 3rd goes to the USB bulkhead connected I added in the centre console. This is how the centre console looks "tidied" up Note I didn't install the provided speaker, didn't use the 2.5mm IPod in line or the piggyback loom for the Ipod or change any DIP switches; they seem to only be required if you need to use the Ipod input rather than the AUX input. That's it, install done, I'll follow up with a separate post on how the unit works, but in summary it retains all factory functions and inputs (so I still use my phone to the car for calls), reverse still works like factory etc.
    • Place the new daughterboard in the case and mount it using the 3 small black rivets provided, and reconnect the 3 factory ribbon cables to the new board Then, use the 3 piggyback cables from the daughterboard into the factory board on top (there are stand offs in the case to keep them apart. and remember to reconnect the antenna and rear cover fan wires. 1 screw to hold the motherboard in place. Before closing the case, make a hole in the sticker covering a hole in the case and run the cable for the android unit into the plug there. The video forgot this step, so did I, so will you probably. Then redo the 4 screws on back, 2 each top and bottom, 3 each side and put the 2 brackets back on.....all ready to go and not that tricky really.      
    • Onto the android unit. You need to remove the top screen because there is a daughterboard to put inside the case. Each side vent pops out from clips; start at the bottom and carefully remove upwards (use a trim remover tool to avoid breaking anything). Then the lower screen and controls come out, 4 screws, a couple of clips (including 3 flimsy ones at the top) and 3 plugs on the rear. Then the upper screen, 4 screws and a bunch of plugs and she is out. From there, remove the mounting brackets (2 screws each), 4 screws on the rear, 2 screws top and bottom and 3 screws holding in the small plates on each side. When you remove the back cover (tight fit), watch out for the power cable for the fan, I removed it so I could put the back aside. The mainboard is held in by 1 screw in the middle, 1 aerial at the top and 3 ribbon cables. If you've ever done any laptop stuff the ribbon cables are OK to work with, just pop up the retainer and they slide out. If you are not familiar just grab a 12 year old from an iphone factory, they will know how it works The case should now look like this:
    • Switching the console was tricky. First there were 6 screws to remove, and also the little adapter loom and its screws had to come out. Also don't forget to remove the 2 screws holding the central locking receiver. Then there are 4 clips on either side....these were very tight in this case and needed careful persuading with a long flat screw driver....some force required but not enough to break them...this was probably the fiddliest part of the whole job. In my case I needed both the wiring loom and the central locking receiver module to swap across to the new one. That was it for the console, so "assembly is the reverse of disassembly"
×
×
  • Create New...