Jump to content
SAU Community

Rb25det Swapped R32 Low Rpm = Low Boost Problem

GTSTLOVE
 Share

Recommended Posts

GTSTLOVE Apprentice

GTSTLOVE

Posted
Posted

Ill cut right to it.

My R32 gts-t came with a S1 rb25det swap already done. it seems like they used the rb20 loom. I know with the rb25 wiring harness the 2 stage boost can be disabled by the solenoid ground wire attached to the body. how can i bypass the rb20's restricted boost (as the 20's didnt have a boost solenoid) and let the rb25det keep 7 psi at low rpms rather than 5 psi from 2500~4500 and then 7-8 psi through the higher powerband?

shorter story

I have a hallman MBC, but when i open up the spring, it doesn't give me any extra boost at all. am i limited until i get a haltech ecu? or can the rb20s boost limiter be disabled to allow more than 5 psi at low rpms?

Sinista32 Grand Master

Sinista32

Posted
Posted (edited)

bought it off carsales very recently?

You'll need an SBC (electronic) if using oem ecu's.

Edit: If you use just the MBC your A/F mixtures will be off. In itself not a biggie but not the best way to go about things.

P.S. You should have had a look at the R32 4 Door - Just saying :P (its mine :D)

Edited by Anonymouse
GTSTLOVE Apprentice

GTSTLOVE

Posted
  • Author
Posted (edited)

When i purchased the car it had a direct line from the I/C to the wastegate. So if i put a MBC between the I/C and wastegate, i will run rich or lean? but it still won't increase boost at low RPM's?

and how can i run a SBC if its a rb20 loom. theres no plug because the rb20s didnt have a boost solenoid

also the ECU is supposedly a mines tuned refurbished rb25/20 ecu. i can't confirm this though. other than the 2 stage boost the car runs smooth and i haven't had any problems at all

Edited by GTSTLOVE
Sinista32 Grand Master

Sinista32

Posted
Posted

my stuff up mate. Don't know what I was thinking. :/

SAFC II for the air fuel if your not considering replacing the stock ECU.

T-boost controller (Manual)

What is the internal wastegate used? and it's PSI rate?

GTSTLOVE Apprentice

GTSTLOVE

Posted
  • Author
Posted

i must have a vaccum leak or boost leak somewhere. I'm running a large FMIC without a BPV/BOV. I get damn near instant spool, but it stays 3-5 psi until 4500 rpm which leads me to believe the 2 stage is still active. This is with either a direct line to wastegate or mbc. im not sure if the wastegate is off a rb20 or 25. id have to research the differences between the 20/25 turbo before i can tell you which im running

KiwiRS4T Grand Master

KiwiRS4T

Posted
Posted

The RB20 has a direct line to the actuator which opens at about 10psi so no 2 stage boost. If you are using the stock RB25 actuator with a direct line also no 2 stage boost. If your manual boost controller is working and correctly plumbed you should be able to raise the boost to better than 10 psi.

Has your new RB25 got an internally wastegated turbo (stock) or has it had an external wastegate fitted?

blind_elk Grand Master

blind_elk

Posted
Posted

If you use the wastegate controller for an RB20DET, then you will get around 10psi available right through the rev range. Then "open up" the dump pipe and you can get a couple more psi.

(this is how my RB25DET in R32GTS4 is set up. I also run the wastegate actuator from the fpr line, so I get full 12psi at the manifold, rather than at the compressor wheel)

KiwiRS4T Grand Master

KiwiRS4T

Posted
Posted

I also run the wastegate actuator from the fpr line, so I get full 12psi at the manifold, rather than at the compressor wheel)

You shouldn't run anything from the fpr line . Boost for actuator ideally comes from compressor or as near as.

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
 Share
Go to topic listing


  • Similar Content

  • Latest Posts

    • Turbodoc
      Noobie Stagea owner..

      By Turbodoc · Posted

      Hey Dave, welcome aboard! Good to see another soon-to-be Stagea owner here. The wagons are awesome — plenty of space, still got that Skyline DNA, and loads of potential if you’re into mods. Definitely post up pics when you get it, everyone here loves seeing new builds. What model/year are you looking at?
    • GTSBoy
      Duncan's V37.......race car?

      By GTSBoy · Posted

      See if you can thermal epoxy a heatsink or two onto it?
    • Duncan
      Duncan's V37.......race car?

      By Duncan · Posted

      The other problem was one of those "oh shit we are going to die moments". Basically the high spec Q50s have a full electric steering rack, and the povo ones had a regular hydraulic rack with an electric pump.  So couple of laps into session 5 as I came into turn 2 (big run off now, happily), the dash turned into a christmas tree and the steering became super heavy and I went well off. I assumed it was a tyre failure so limped to the pits, but everything was OK. But....the master warning light was still on so I checked the DTCs and saw – C13E6 “Heat Protection”. Yes, that bloody steering rack computer sitting where the oil cooler should be has its own sensors and error logic, and decided I was using the steering wheel too much. I really appreciated the helpful information in the manual (my bold) POSSIBLE CAUSE • Continuing the overloading steering (Sports driving in the circuit etc,) “DATA MONITOR” >> “C/M TEMPERATURE”. The rise of steering force motor internal temperature caused the protection function to operate. This is not a system malfunction. INSPECTION END So, basically the electric motor in the steering rack got to 150c, and it decided to shut down without warning for my safety. Didn't feel safe. Short term I'll see if I can duct some air to that motor (the engine bay is sealed pretty tight). Long term, depending on how often this happens, I'll look into swapping the povo spec electric/hydraulic rack in. While the rack should be fine the power supply to the pump will be a pain and might be best to deal with it when I add a PDM.
    • Duncan
      Duncan's V37.......race car?

      By Duncan · Posted

      And finally, 2 problems I really need to sort.  Firstly as Matt said the auto trans is not happy as it gets hot - I couldn't log the temps but the gauge showed 90o. On the first day I took it out back in Feb, because the coolant was getting hot I never got to any auto trans issues; but on this day by late session 3 and then really clearly in 4 and 5 as it got hotter it just would not shift up. You can hear the issue really clearly at 12:55 and 16:20 on the vid. So the good news is, literally this week Ecutek finally released tuning for the jatco 7 speed. I'll have a chat to Racebox and see what they can do electrically to keep it cooler and to get the gears, if anything. That will likely take some R&D and can only really happen on track as it never gets even warm with road use. I've also picked up some eye wateringly expensive Redline D6 ATF to try, it had the highest viscosity I could find at 100o so we will see if that helps (just waiting for some oil pan gaskets so I can change it properly). If neither of those work I need to remove the coolant/trans interwarmer and the radiator cooler and go to an external cooler....somewhere.....(goodbye washer reservoir?), and if that fails give up on this mad idea and wait for Nissan to release the manual 400R
    • Duncan
      Duncan's V37.......race car?

      By Duncan · Posted

      So, what else.... Power. I don't know what it is making because I haven't done a post tune dyno run yet; I will when I get a chance. It was 240rwkw dead stock. Conclusion from the day....it does not need a single kw more until I sort some other stuff. It comes on so hard that I could hear the twin N1 turbos on the R32 crying, and I just can't use what it has around a tight track with the current setup. Brakes. They are perfect. Hit them hard all day and they never felt like having an issue; you can see in the video we were making ground on much lighter cars on better tyres under brakes. They are standard (red sport) calipers, standard size discs in DBA5000 2 piece, Winmax pads and Motul RBF600 fluid, all from Matty at Racebrakes Sydney. Keeping in mind the car is more powerful than my R32 and weighs 1780, he clearly knows his shit. Suspension. This is one of the first areas I need to change. It has electronically controlled dampers from factory, but everything is just way too soft for track work even on the hardest setting (it is nice when hustling on country roads though). In particular it rolls into oversteer mid corner and pitches too much under hard braking so it becomes unstable eg in the turn 1 kink I need to brake early, turn through the kink then brake again so I don't pirouette like an AE86. I need to get some decent shocks with matched springs and sway bars ASAP, even if it is just a v1 setup until I work out a proper race/rally setup later. Tyres. I am running Yoko A052 in 235/45/18 all round, because that was what I could get in approximately the right height on wheels I had in the shed (Rays/Nismo 18x8 off the old Leaf actually!). As track tyres they are pretty poor; I note GTSBoy recently posted a porker comparo video including them where they were about the same as AD09.....that is nothing like a top line track tyre. I'll start getting that sorted but realistically I should get proper sized wheels first (likely 9.5 +38 front and 11 +55 at the rear, so a custom order, and I can't rotate them like the R32), then work out what the best tyre option is. BTW on that, Targa Tas had gone to road tyres instead of semi slicks now so that is a whole other world of choices to sort. Diff. This is the other thing that urgently needs to be addressed. It left massive 1s out of the fish hook all day, even when I was trying not too (you can also hear it reving on the video, and see the RPM rising too fast compared to speed in the data). It has an open diff that Infiniti optimistically called a B-LSD for "Brake Limited Slip Diff". It does good straight line standing start 11s but it is woeful on the track. Nismo seem to make a 2 way for it.
×
×
  • Create New...