Jump to content
SAU Community

Recommended Posts

So I have an RB25 S2 with a GT3076r low mount at the moment. I’m looking at changing it to high mount setup. Was look to get some feedback on what exhaust housing size I should go eg: .73 or .82

Current setup made 18psi at 4000rpm making a max HP of 330 when it was first tune. Now the internal gate is giving me the shits and doesn’t make 18psi until 5500. I’m not wanting too much lag and will be happy if I get 18psi at 4000rpm once again on the high mount setup.

Supporting mods will be:

Greedy intake man

Front mount

Split fires

Power fc

3.5 inch exhaust

38mm external gate

I have looked through the Forms to try and find this information but no luck

Link to comment
https://www.sau.com.au/forums/topic/403526-rb25-gt3076r-turbine-housing-size/
Share on other sites

  • Replies 57
  • Created
  • Last Reply

Top Posters In This Topic

.82

Smaller than that will restrict flow up top and with .82 on ext gate you should see full boost by 4000rpm

You should have made more than 330hp with a 3076r with a low mount though...

Edited by Mitcho_7

Be prepared to put in the money if you want to go a proper high mount setup with FFP, i was shocked when i realised how much my car cost to do.

Is saying that its a 3076/3037 and see's 21psi @ 3900 rpm easily and makes 485hp

You should be able to get a nice responsive 400hp in the low mount setup, there must be something wrong with the way you have it setup!

The tune was done at pits

The intake man was put on after the tune but had boost issues before that

First turbo setup was with an apexi AX53B70 made 292HP hit 18 psi at 3500rpm then droped back to 14psi at 8000rpm so when the GT3076r when on and made about 40hp more i thought i was doing ok

and yes 550cc injectiors fuel reg and fuel pump done with a Z32 AFM

Edited by gts-t 32

My last setup was just a high flow turbo, nothing special and it made 330-340hp at only 13psi so a 3076 can do better if its setup right, the turbo is a small piece of the puzzle :)

My highflow makes 240rwkw on a safe tune, so I definently think you should sort out what's holding things back at the moment before you go dropping $$$ on a high mount.

Who knows, you might end up being happy with the result, as is, when you get the issues sorted!

There is an issue with your current setup.

+1

And going to highmount wont magically fix it.

There is no reason an internal gate GT3076 on 18psi cannot make 260-270rwkw without issue. No-one else has problems with correctly sorted setups, so fix the current one before changing as the issue is clearly not turbo related.

You havent mentioned what rear housing you have at the moment.

I bet you have one of the following:

- 'skyline style' 6 bolt outlet for GT30s, by ATP or someone similar (bolts to the stock style dymp)

- Garret .63 5 bolt rear housing

Please clarify which one you have. If you have EITHER of those housings, that is your problem.

Change to a genuine garrett 5 bolt .82 rear housing and you will get the response AND get closer to 400whp.

The tune was done at pits

The intake man was put on after the tune but had boost issues before that

First turbo setup was with an apexi AX53B70 made 292HP hit 18 psi at 3500rpm then droped back to 14psi at 8000rpm so when the GT3076r when on and made about 40hp more i thought i was doing ok

and yes 550cc injectiors fuel reg and fuel pump done with a Z32 AFM

That is low power even for the Apexi turbo, i have an ax53b70 and made 340hp on 16psi, 555cc, z32 and the usual other mods.

You havent mentioned what rear housing you have at the moment.

I bet you have one of the following:

- 'skyline style' 6 bolt outlet for GT30s, by ATP or someone similar (bolts to the stock style dymp)

I think it might be sonic or something that makes those

Yes you guys are right, its a Sonic. The first week it was on it was great then I had to take it off and sent it back to sonic as the sleeve for the gate had come lose and wouldn't allow the internal gate to close. I still don’t think it is right and that’s why I want to get rid of it

The only other thing that could be letting it down is the monster performance intercooler brought of a mate a long time ago I’ve been meaning to upgrade it.

Yes I have tried preloading the wastegate more.

All other parts are good quality

Sard 550 injectors

Genuine greddy intake manifold

AVCR

nismo fuel pressure regulator

splitfire coil packs

z32 AMF with steel intake to turbo

Power FC

And a walbro fuel pump

Pits dyno is known for low HP readings but he is very good with Power FC

http://www.skylinesaustralia.com/forums/topic/127439-pitsmatty-spry-dyno/

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

    • Look for broken wire or bad connector at the motor. Might not be it, but is worth starting there, as it is easy.
    • Hi everyone, I’m having an issue with my R32 GT-R. Sometimes, when the car goes over a bump or experiences some vibration, the 4WD warning light comes on the dashboard. When I check the code from the control unit in the trunk, it shows Code 19 – ETS Motor. However, everything seems to be working fine — if I turn off the engine and restart the car, the light goes away and everything functions normally. Has anyone experienced this before? Where should I start troubleshooting this issue? Thanks in advance!
    • I'm back from the dyno - again! I went looking for someone who knew LS's and had a roller dyno, to see how it shaped up compared to everything else and confirm the powerband really is peaking where Mr Mamo says it should. TLDR: The dyno result I got this time definitely had the shape of how it feels on the road and finally 'makes sense'. Also we had a bit more time to play with timing on the dyno, it turns out the common practice in LS is to lower the timing around peak torque and restore it to max after. So given a car was on the dyno and mostly dialled in already, it was time for tweaking. Luis at APS is definitely knowledgable when it came to this and had overlays ready to go and was happy to share. If you map out your cylinder airmass you start seeing graphs that look a LOT like the engine's torque curve. The good thing also is if you map out your timing curve when you're avoiding knock... this curve very much looks like the inverse of the airmass curve. The result? Well it's another 10.7kw/14hp kw from where I drove it in at. Pretty much everywhere, too. As to how much this car actually makes in Hub Dyno numbers, American Dyno numbers, or Mainline dyno numbers, I say I don't know and it's gone up ~25kw since I started tinkering lol. It IS interesting how the shorter ratio gears I have aren't scaled right on this dyno - 6840RPM is 199KMH, not 175KMH. I have also seen other printouts here with cars with less mods at much higher "kmh" for their RPM due Commodores having 3.45's or longer (!) rear diff ratios maxing out 4th gear which is the 1:1 gear on the T56. Does this matter? No, not really. The real answer is go to the strip and see what it traps, but: I guess I should have gone last Sunday...
    • 310mm rotors will be avilable from Australia, Japan, and probably a few other places. Nothing for the front can be put on the back.
    • The filter only filters down to a specific size. Add to that, the filter is AFTER the pump. So it means everything starts breaking your pump even if its being filtered out.
×
×
  • Create New...