Jump to content
SAU Community

That Drop !

r34unit

By r34unit,
in Engines & Forced Induction

 Share

Recommended Posts

scotty nm35 Grand Master

scotty nm35

Posted
Posted

I assume you are talking internal gate housings Angelo? Most setups I have seen hold nicely near spring pressure, as you try and bleed them up it can all go to crap due to manifold pressure.

It's not such a bad thing to drop a little boost in the top end, the engine is ingesting a lot of air up there and boost is only a measure of the engines lack of airflow. Why overspin the compressor when most of the time it is just producing hotter air...

A larger turbo and or housing will always help top end flow.

Link to comment
Share on other sites
r34unit Rising Star

r34unit

Posted
  • Author
Posted

I'm running a gt3076 on a rb25 manifold with a 38mm external gate welded off it. It does not spike at all but in the top end it drops from 19psi to 16,15 psi.

I'm using a blitz sbs dual solenoid ebc.

Might need to test for a boost leak !

But if any other ideas come to mind on what it could please let me know !

Link to comment
Share on other sites
Lithium Grand Master

Lithium

Posted
Posted

I don't think there is a housing which will cause that issue - when I had a .63 housing on mine I struggled to keep it UNDER that boost level, it was hitting 20psi by 5700rpm and trying to climb hard. The only reason the turbo itself would not be able to hold boost (assuming it's healthy) is if it is struggling to keep up with the airflow requirements of that engine at that boost level. Even a .63 GT3076R shouldn't have issues, really the compressor and turbine should be able to hold 20+psi "all in" so if it's not holding, it will be something to do with the setup - wastegate/boost controller/boost leak/exhaust leak/something...

Link to comment
Share on other sites
scotty nm35 Grand Master

scotty nm35

Posted
Posted

I'm running a gt3076 on a rb25 manifold with a 38mm external gate welded off it. It does not spike at all but in the top end it drops from 19psi to 16,15 psi.

I'm using a blitz sbs dual solenoid ebc.

Might need to test for a boost leak !

But if any other ideas come to mind on what it could please let me know !

Pressure test the intake by all means.

What spring are you using in the wastegate?

Are you using a MAC valve to hold the gate closed also?

Link to comment
Share on other sites
r34unit Rising Star

r34unit

Posted
  • Author
Posted

My apologies! I've just realized It's a Garrett gt3037s 56t in a .82 rear housing !

I'm using the big black blitz dual solenoid.

Now I'm wondering if the .82 rear is too big ? And I should change to a .74

Link to comment
Share on other sites
scotty nm35 Grand Master

scotty nm35

Posted
Posted

No, you just need to sort out your boost control. Shouldn't be too difficult to work out.

Just slapping an electronic controller won't make a 4psi spring hold 30psi, you need to first match your spring to be close to your desired output, then the controller might have a fighting chance of holding what you set it at.

If that fails, you need to hold the gate shut using pressure to the top port on the gate. You would need to swap to a 4 or 5 port MAC valve to do this properly, simply cut the old solenoid out and solder the MAC in it's place.

Link to comment
Share on other sites
GTScotT Grand Master

GTScotT

Posted
Posted

It sounds like a boost control issue, otherwise you have all the parts to support what you want to do.

Obviously you should still check for leaks, but move to boost control if you cant find any leaks.

Link to comment
Share on other sites

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

    • 180 wanabe
      Thinking of getting a Q50 300hp and just tuning it instead of getting the Q50 Red or 400R

      By 180 wanabe · Posted

      So next year I am looking at upgrading from my VE SS bomadore ute to something more refined.  I wanted to stick with a V8 but not anything German or Australian, either a coupe or a sedan. So if I wanted anything newish that limited my options to either the Lexus RCF which I quite like. But with the price they demand and a kid on the way a 2 door coupe is probably not going to be the best idea. The next best thing would be the ISF but the newest models are 2014 and commanding over 60k and even the older 2008 models in ok condition starting around 35k is kind of bullshit. So I figured if I could not have the noise I could perhaps make do with easy power. Enter the infinity Q50 or Skyline equivalent. The price difference between the 300 and 400hp models seems a bit crazy. Right now there is 300hp Q50 one on carsales from a dealer with 61km for 27k drive away. If I wanted to get a 400hp Red or 400R car the prices seem to start at 43k From my limited research it seems that the only differences are that the 400r/Red Red runs more boost and a more aggressive tune. There are are turbine speed sensors on the turbos. Has 2 pumps for the water to air intercooler. Runs an engine oil cooler. I'm guessing that the exterior trims might look a little more sporty as well. I had a lazy look for upgrades to bridge the gap on z1motorsports They have kits that upgrade the water to air heat exchanger as well as the coolant pump which should give a non Red/400r better intercooling temps than the stock Red/400r. I added an engine oil cooler with a thermostat as well to try and make things as close as possible. Obviously the ECU is going to need a tickle. Having not done much in the way of research they also sell a ECU flashing tool with pre loaded tunes that are supposed to boost the non Red/400R by 100hp which adds 1k USD to the cost. The total cost of the parts @ the current time including shipping and taxes worked out to be $4350 AUD. Personally I would rather get the car tuned on a dyno which would probably add more cost Assuming the worst that you got a workshop to install the new parts I would guess no more than 5 hours would be required in the worst case @ 5 x $150 per hour = $750 So the total cost could be around $5100 So for easy number 5k + 27K = 32k I guess that would leave some change left over to swap out the open diff and fit a LSD Any thoughts?      
    • joshuaho96
      Blow Off Valve Is Causing Car To Stall!

      By joshuaho96 · Posted

      Right, not sure why I thought it to be a lean spike. It might be fixable with modern card-style hot film MAFs which have some design features to avoid counting reversion flow but I've never tried it myself.
    • Leigh_Mack
      Hello, Newbie, anyone know my 32's history?

      By Leigh_Mack · Posted

      I did not realise this, I'll contribute more and earn my stripes and retry later. 
    • GTSBoy
      Hello, Newbie, anyone know my 32's history?

      By GTSBoy · Posted

      I'm only going to hassle you for posting links to images. It's against my policy to click links that could be some nasty payload. Sadly, you need to make 9 more posts before you can just stick the images directly in a post, unless @PranK sees this and bends the rule for you.
    • Leigh_Mack
      Hello, Newbie, anyone know my 32's history?

      By Leigh_Mack · Posted

      Hello,new to the group, I bought a R32 from auction recently, wondering if anyone knows the cars history, seems to have the usual go fast bits on it, plan is to do an engine swap- add 2 extra cylinders and 1 extra turbo. https://www.dropbox.com/scl/fi/i4rjmlzubjbwjtguh6f4s/IMG20241011140744.jpg?rlkey=q0lumm251377vknbqktfwrycq&st=7scvwx4e&dl=0 https://www.dropbox.com/scl/fi/ro24qmwzlczzlfsr4y05x/Screenshot_2024-10-10-10-49-23-90_9a2f5bb2149dae94cd1e190effc09b33.jpg?rlkey=oyguh26ttshlf04ccp48odf4v&st=xloae97b&dl=0   New to forums and posting pics, if links don't work, take it easy on me, 42yrs old and I tune carburettors!!  
×
×
  • Create New...