Gt3076r Not Holding Boost

[limpus]

Hey guys,

I'm having a problem with holding boost properly with my garrett 3076r...its ramping up to 21psi but then tapering off to 18psi above 5000rpm...i'd ideally like to have it hold 21psi across the rev range...

Setup is a little different though...

Toyota Supra

2JZ-GTE

Custom low mount manifold

Garrett 3076R 56T 0.82 IW with Garrett big can 18psi actuator (preload is set right and its achieving 17-18psi with the boost controller off)

4" intake pipe

Sard 280LPH fuel pump

FMIC

3" exhaust

PFC

AVCR

I've had the car on the dyno twice trying to get proper boost control but i can't stop the boost from falling off...the rb30det boys suggested using the 18psi actuator which i've got and its still not doing it...the boost curve looks almost idetical with the old smaller 14psi actuator and the bigger 18psi one...its still ramping up very well and 20psi is achieved by about 3300rpm...but then it justs falls off by 5000+rpm...i've tried tweaking the AVCR with numerous different settings and all it does is cause boost to ramp higher (23-25psi) before falling back to 18psi again...

Does anyone have any input on this...note that external wastegate is not a valid response...

[Trozzle]

Why do I want to derail this thread SO BADLY?

Looks like your Genuine Garrett item is no better than the Hypergear item you spent so much time badmouthing.

Although to add a relevant response, since I haven't seen results of this turbo at that boost on a 3L....what are the chances it's either running out of puff, or that the exhaust flow from 3L engine against the wastegate on top of the boost pressure against the actuator are causing it to not hold closed as much as desired? I know that last situation isn't likely, but perhaps it just can't flow what your engine wants to swallow.

[Lithium]

Looks like your Genuine Garrett item is a lot better than the Hypergear item you spent so much time badmouthing.

Fixed. We know the GT3076Rs spool faster than a 300+kw Hypergear turbo, and here it is holding similar boost on a 2JZGTE as what the Hypergear does on an RB25... its clearly able to pump some air to do that.

I'd say however that at that boost level its a good chance that its just maxing out, its not that large a turbo for a decent flowing 3litre - how much power are you getting out of it at that boost level?

[Rolls]

Sounds like the gate is blowing open, is it internally gated or externally?

[Trozzle]

Fixed. We know the GT3076Rs spool faster than a 300+kw Hypergear turbo, and here it is holding similar boost on a 2JZGTE as what the Hypergear does on an RB25... its clearly able to pump some air to do that.

I'd say however that at that boost level its a good chance that its just maxing out, its not that large a turbo for a decent flowing 3litre - how much power are you getting out of it at that boost level?

I fail to see how that's any more correct than my obvious troll post, given his above posted results.

[R.3.2.G.T.R]

try a better boost controller

[Crans]

Nothing wrong with the AVCR its actually one of the better boost controllers on the market. You just need to know how to set it up properly.

[SimonR32]

Fixed. We know the GT3076Rs spool faster than a 300+kw Hypergear turbo, and here it is holding similar boost on a 2JZGTE as what the Hypergear does on an RB25... its clearly able to pump some air to do that.

STATUS posted a Hypergear vs 3071R graph a few days ago which would say different. They were for all intensive purposes identical spool... Unless you are going to claim a 3076R will spool faster than a 3071R?

Edited October 28, 2010 by SimonR32

[hypergear]

I give you some advise either way.

I've managed to hold 22psi on a RB30det VL, of a customer's car. Needs custom made twin spring actuator with gate controller. If you really want to stick with Garrett Actuators try: 446131-23 .

If that doesn't work, send in your turbine housing for modifications. Which I will charge you a million dollars .

[Lithium]

Trozzle - I added 2c in regards to why it COULD be boost dropping... when I chose a GT3076R for my RB25 I was aiming for a setup which could flow efficiently enough to push around 22psi of boost into a 2.5litre up to 7000rpm without being silly about it. To do the same on a 3litre I'd personally be looking at using something more like a GT3582R, so really I'd expect the required solenoid duty cycle to maintain 22psi or so in the higher revs to go WAY up when used on a 3litre in higher revs as IMHO the turbo will start hitting its flow limits.

Other obvious things to check would be if there are any leaks, either exhaust or intake side. Also, I am not convinced on AVC-Rs at all... when I had the softer actuator on mine I couldn't convince it to bring it anywhere near strong enough onto full boost, I had to upgrade to an 18psi big can unit.

Its doing the same things the Hypergear turbos which were used to crack 300kw were doing on RB25s... if you don't quite understand that "boost" isn't a universal thing, what this means is that if you put the 300kw Hypergear turbo onto the larger 2JZGTE and this IS what the problem is - there is a good chance you'd see full boost reached slightly later than the GT3076R, but then boost dropping earlier again and a net result of less hp in the top end.

STATUS posted a Hypergear vs 3071R graph a few days ago which would say different. They were for all intensive purposes identical spool... Unless you are going to claim a 3076R will spool faster than a 3071R?

I gave up following the Hypergear threads after there were "not all being equal" factors used too consistantly which could skew things to make it seem the Hypergear was better in comparison than it really was, so not sure exactly what was shown and as such can't really comment. I'm not one eyed or stupid and also don't try and pull the wool over peoples eyes so don't see why you are implying I would suggest a GT3076R would spool better than a GT3071R, keep that brush on the people who do that kind of thing.

[limpus]

To all the haters...you can say whatever you want regarding this...i've said my piece the other turbos and i stand by it...feel free to keep spouting crap...i've long stood by the motto that you should only dish it out if you can take it...

I chose this turbo because other RB30DET members on here have gotten good results on their cars with this setup...and with the 18psi garrett actuator too...yes the 3076R is a tad small for a 3L...i know that...but i chose it because peak power wasn't the aim...maximum response was the aim with 300rwkw in mind...and it does that...no complaints there...also...i wanted to be the first to do a low mount single setup in victoria just to prove it could be done...and i've proven it...have a look in the RB30 thread for some examples...i'm staying out of comparisons between rb25s here as a 2JZ is a whole different kettle of fish...

[WYTSKY]

STATUS posted a Hypergear vs 3071R graph a few days ago which would say different. They were for all intensive purposes identical spool... Unless you are going to claim a 3076R will spool faster than a 3071R?

Maybe it does? Garrett 3076r: 18psi 3000rpm

[HEKT1K]

If peak power isn't your aim, why are you complaining about boost dropping off in the top end? Honest question.

Always going to happen with that size turbine housing on a 3L.

[zebra]

Would trying a 1.06a/r turbine housing be an option?

[Harey]

Maybe it does? Garrett 3076r: 18psi 3000rpm

LOL u cant compare a 0.63 3076 to a 0.82 3071. Also, not to mention your higher compression.

[kwickr33]

I gave up following the Hypergear threads after there were "not all being equal"

Its also not been equal that you are running on a "NZ dyno" with all the enchantments for better response. This also made you the most responsive 3076R .82 int gate through out Australia. Far better then some with cam gears and external gates. Run that on Status dyno and see what happens.

[limpus]

If that doesn't work, send in your turbine housing for modifications. Which I will charge you a million dollars .

Since we're all joking here...if i had a million dollars...i'd start a turbo highflow service and claim a gazzzillion KW at 1000rpm...

But seriously...if you can find people with 2Js for you to trial your constant R&D and pulling off and replacing turbos on a contant basis and get the results i'm after then i might consider your products...if not...then nah...

[limpus]

If peak power isn't your aim, why are you complaining about boost dropping off in the top end? Honest question.

Always going to happen with that size turbine housing on a 3L.

Well...peak power isn't the aim...area under the curve is the aim...and with consistant boost pressure i'd get more area...

The turbine housing can do it...proven here in this thread...http://www.skylinesaustralia.com/forums/Gt....html&st=20

So the issue is more likely to lie with my setup...and not my turbo...which some people seem to be wishing for...

[hypergear]

Since we're all joking here...if i had a million dollars...i'd start a turbo highflow service and claim a gazzzillion KW at 1000rpm...

But seriously...if you can find people with 2Js for you to trial your constant R&D and pulling off and replacing turbos on a contant basis and get the results i'm after then i might consider your products...if not...then nah...

Seriously I can really make that work and hold it at what ever "high" settings you want it to set it. even at 24psi as long as the turbo it self can take it (assume engine's won't have issues).

[WYTSKY]

LOL u cant compare a 0.63 3076 to a 0.82 3071. Also, not to mention your higher compression.

was just joining in with the joking sarcasm sucks on the net!