Jump to content
SAU Community

Help Understand GTT Boost Setup

DraftySquash

By DraftySquash,
in General Maintenance

 Share

Recommended Posts

DraftySquash Enthusiast

DraftySquash

Posted
Posted

Hi everyone,

Apologies in advance if this feels like a topic covered multiple times. I'm only asking because some of the old topics I found are missing images now.

I'm in the process of getting a manual boost controller (BC). Nothing fancy, just getting a manual one for now as I don't plan to go crazy with it and would not go over 10 PSI. My car is not jacked up on boost steroids to do crazy numbers.


I want to understand the OEM setup of the boost solenoid and vacuum lines on the R34 GTT so I know what needs to be changed when I do install the BC. I sketched the current setup to the best I could see and it's on the diagram attached.
Frame1776.thumb.png.06235d67f369c9b6d57ea7b0f0e72801.png


If the boost controller 'Wastegate Arrow' goes from nipple 1 to 2. My understanding is that the red vacuum line's "F" connector-end should be connected to BC nipple #2?
Nipple #1 is meant to have the "pressure source" so what vacuum line would that be? Is it the green vacuum line? 

From what I have read here, the OEM boost solenoid is not used at this point. So that can come out and then I can just plug the nipple that usually connects to the blue vacuum line? 

So would the final setup look something like this?

final.thumb.png.b0673874c665c990a21a463465b3ec13.png

 

Thanks in advance. I don't want to already be knee-deep into pulling out vacuum lines before understanding this. I'm a noob when it comes to boost setups so trying to learn as I go.

Link to comment
https://www.sau.com.au/forums/topic/486110-help-understand-gtt-boost-setup/
Share on other sites
GTSBoy Grand Master

GTSBoy

Posted
Posted

The stock boost solenoid is just a valve. Power it and it is open. Unpowered, it is closed.

When it is closed, there is no boost bleed out through the solenoid back to the inlet. The wastegate sees all the boost pressure, thus you get the wastegate's spring pressure as your boost pressure. 5 psi.

When it is open, it lets some boost escape. This causes the static (boost) pressure in the line to the wastegate to be lower than the pressure in the intercooler pipe. There is probably a small restrictor in the solenoid or one of its lines to limit the flow rate of the escaping air, which limits how far the static pressure can fall, which limits the extra boost. The boost has to climb above the original/wastegate setpoint until the wastegate sees 5 psi. You get 7 psi in the intercooler pipework.

A manual boost controller is exactly the same setup, just without the ability to change it on-off. It's always set to whatever you set it to. There is a small leak from the boost controller. The more you screw the adjuster in, the more it leaks, the lower the pressure seen at the wastegate and the higher the boost will be.

So, yes, your diagrams are correct.

  • Thanks 1
DraftySquash Enthusiast

DraftySquash

Posted
  • Author
Posted

@GTSBoy that’s good information and thanks for sharing that. 
I’ve read the GTT has 2 stages of boost? 5psi or so at lower RPMs and then 7psi. 
So I assume, with a boost controller it will be one standard pressure. I got no issue with that until I invest in an electronic boost controller.

With the setup after the boost controller, should I still keep the solenoid plugged in to power? Just so the ECU is happy? Or does unplugging it and completely removing it cause no issues? 


I’ve got myself booked in for a Nistune install and tune next Monday so pretty excited 😝 

GTSBoy Grand Master

GTSBoy

Posted
Posted

The ECU doesn't care if the solenoid isn't there. There's no sensing/feedback from the solenoid. The ECU just gives it power, or not.

Make sure that you Nistune tuner knows damn well how to tune a Neo. They suck. You have to take a lot of care to override bullshit to do with the boost sensor and a few other things to stop them being a dick.

DraftySquash Enthusiast

DraftySquash

Posted
  • Author
Posted (edited)
On 11/2/2025 at 9:51 PM, Milkmun said:

Who's doing your Nistune install and tune? 

Could always ask them to install the MBC.

It’s Shane at CMS performance doing the tune. 
 

CMS performance was the only place in VIC I could find that would supply, install and tune (and had good feedback)

Yeah that might be a good idea 😂

Less chances of fkn it up 

Edited by DraftySquash
Milkmun Collaborator

Milkmun

Posted
Posted
On 11/02/2025 at 10:04 PM, DraftySquash said:

It’s Shane at CMS performance doing the tune. 
 

CMS performance was the only place in VIC I could find that would supply, install and tune (and had good feedback)

Yeah that might be a good idea 😂

Less chances of fkn it up 

Big drive from the west to Seaford. Good luck man, let us know how it all goes.

DraftySquash Enthusiast

DraftySquash

Posted
  • Author
Posted
On 11/2/2025 at 10:15 PM, Milkmun said:

Big drive from the west to Seaford. Good luck man, let us know how it all goes.

lol I know!!

I’m actually staying over at a mate’s place in SE the night before. 
not because I don’t like the long drive. I just don’t want to drive from West to Seaford around 8am on a Monday 😂

traffic would be wild. 
 

The Skyline actually does the West to SE trip without issues. My family is on that side. 

DraftySquash Enthusiast

DraftySquash

Posted
  • Author
Posted

I think a 60-90 mins drive is worth it, if the mechanic is good and has experience. 
that’s what I’ve heard about CMS, so I’ll let you know how I go after Monday 

Kinkstaah Grand Master

Kinkstaah

Posted
Posted

I have a friend who has used Chequered Tuning and CMS. Went to CMS when Chequered had a long wait time which is kind of the norm (for good reason).

Was very happy - I'm pretty sure the very simple thing you're asking will be simple.

  • Like 1
DraftySquash Enthusiast

DraftySquash

Posted
  • Author
Posted
On 12/02/2025 at 9:31 AM, Kinkstaah said:

I have a friend who has used Chequered Tuning and CMS. Went to CMS when Chequered had a long wait time which is kind of the norm (for good reason).

Was very happy - I'm pretty sure the very simple thing you're asking will be simple.

@Kinkstaah yeah I initially checked with Chequered as I've used them with a previous car. But they have stopped sourcing and installing Nistune chips. They only do tuning now.

I did not want to pull out my ECU and send it away somewhere to have the chip installed. That would mean no driving the Skyline :D 

Kinkstaah Grand Master

Kinkstaah

Posted
Posted

Just putting it out there, that's a decent list.

You would be better off *not* doing *any* of that and buying someone else's modded car. Like mine. Or anybody else's. Yes it's lotto dependent and all this and that but that 70K (remember, double your guesses) could go elsewhere. Keep it stock, save your money, go lowball @Dose Pipe Sutututu :p

  • Haha 1

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

    • GTSBoy
      WTB noltec r32 front upper (camber) arms

      By GTSBoy · Posted

      I'm firmly on the "zero compliance is good compliance" for FUCAs. I'd be looking to solid metal joints even if the primary reason for having them is because they facilitate the twist in the arm. I have never been more happy with the way the front suspension behaves than I have since I got rid of the FUCA bushes. Even the thin little (short lived) poly bushes in the Whiteline adjustables have too much compliance for my liking. It probably won't be long before I have sphericals nearly everywhere, probably including both top and bottom arms in the rear, and I'll start complaining about the increased costs for dental work. But I will be enjoying the driving more, I'm sure.
    • GTSBoy
      Brake pad Compound suggestion

      By GTSBoy · Posted

      Plus, you'll get great experience in bedding in pads!
    • Matvei27
      WTB noltec r32 front upper (camber) arms

      By Matvei27 · Posted

      I have offset Nismo brackets so the fact the gktechs can pivot is less important to me. I have 170mm JIC arms with bushings - but they provide no adjustment and I'm not sure whiteline eccentric bushings will fit them (I don't want to ruin the bushings currently in them to find out). Ideally I want something with bushings + adjustment; hence why I'd like to find a pair of these. Unfortunately they aren't easy to find.
    • Murray_Calavera
      Brake pad Compound suggestion

      By Murray_Calavera · Posted

      @Vee37 How much do you really care about finding these pads again? If your pads are quiet, work well and produce minimal dust, really isn't that enough? If you are set on finding the exact pads again, I suppose I'd do something like this -  Visit your local Jax, find out what brand of pads they carry. If the Jax workshop you previously went to had the pads on the shelf, then you can almost guarantee it will be of said brand.   I'm guessing you don't have the receipt for the previous work and pads. Can you visit a Jax workshop and see if they can look up your previous job to see what pads were fitted?  Still no luck? Put your stalker hat on, find the staff that used to work at the Jax store and ask them. Talk to local workshops, try to find out where the mechanics went to. Talk to Jax workshops, maybe they relocated to another workshop. When it comes to mechanics, its a small world. You'd be surprised how easy it is to track someone down. If these ideas don't work, shit will start getting crazy very quickly.... You could find out every brand and model of pad that fits that car... and try them individually ticking each off the list if it wasn't the one you were looking for.... If you go down this path your going to want to learn how to swap pads yourself, it is very easy, takes minimal tools and space. If you have room to park the car you have room to swap the pads. Plus you have the advantage of making sure all the brake hardware goes back in so they won't squeal! 
    • MBS206
      Beers and skylines Fatz style

      By MBS206 · Posted

      You miss spelled bearings...
×
×
  • Create New...