Rb25 Gt3076R Turbine Housing Size

[gts-t 32]

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

[Mitcho_7]

.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 June 27, 2012 by Mitcho_7

[wolverine]

There is an issue with your current setup.

[Mitcho_7]

You haven't listed any injectors or fuel pump in your mod list, have you upgraded them?

If not, do it before you think about a high mount etc...

[34GeeTeeTee]

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!

[gts-t 32]

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 June 27, 2012 by gts-t 32

[34GeeTeeTee]

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

[Mitcho_7]

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!

[DVS JEZ]

Wat boost controller?

Have u tried preloading the wastegate more

Pic of dyno sheet?

[R31Nismoid]

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.

[GTScotT]

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.

[R31Nismoid]

Yeah or that - I forgot about the possibility of using a butchered housing

[ECR-033]

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.

[Mitcho_7]

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

[GTScotT]

Yeap Sonic is the one, those pieces of shit.

Originally they were sold by ATP but now places like MTQ sell them as a Sonic branded thing.

[wolverine]

That turbine housing isn't going to cause shitty boost response but it will cap power output.

The poor boost response will be an intake leak, exhaust restriction or actuator setup issues IMO.

[Dajae]

Still cant get my head around those low power figures..

Edited June 27, 2012 by Dajae

[gts-t 32]

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/

[gts-t 32]

photos

[GotsWapan]

I have one of these rear housings in the .82 tuned on low boost at the moment.

Am I doomed for life?