Garrett Gt3071r Discussion & Results

[Dragonforce]

Ahh man, seeing your fun and games with this is making me want to use a high mount manifold and external gate..

Less headache would so be worth the extra cash for the manifold/gate.

Hope u can get it working how you want it...

[Dale FZ1]

This creeping boost saga is a mind-bender, and I don’t know that there is a clear cut answer. The tendency to rise and fall regardless of whether running straight off the actuator or EBC gives a few clues, and yeah it is clearly a balancing act to get everything working together properly with this 0.63 A/R spec IW housing. Possibly a large diameter wastegate actuator can is part of the solution, as suggested? Given the actuator will have a limited range of travel, is there any evidence of flex/bend in the actuator mounting bracket? That might be a telltale of backpressure trying to force it further open.

Observed boost levels are falling back to the targeted level as rpm (and mass-flow of gases) rise. That could be due to skyrocketing turbine inlet pressure; or alternatively massive venting through the wastegate causing turbine speed to fall away.

If the backpressure rose out of proportion to boost pressure, then measured boost will drop because backpressure works against the boosted inlet charge. Monitoring turbine inlet pressure would tell virtually all you would need from a turbine efficiency / flow / wastegate capacity perspective. The HKS Pro S housing actually has a threaded hole right below the turbine inlet flange - just the ticket for screwing in a pressure fitting.

Tracking turbine speeds is achieveable with the kit now offered by Garrett, but IMO it’s a bit of overkill for a one-off use unless there are the $$ available. Still, it is great that the gear is available to data acquisition nutters at reasonable prices.

Getting to a solution without spending big $$ or investing/wasting lots of time, first thing I would do is look for bend/flex in that actuator bracket. Secondly, check for any evidence during dyno running, or your road testing, of knock? (presuming you've got a PFC and Datalogit access). A cluey tuner will have a good idea whether backpressure + scavenging issues are inhibiting the tune and inducing knock.

You could go on searching for the cause/s, but the key is whether it is boosting predictably and not just running away when you really want 100% reliability at the track. Apart from the fact that it is overboosting then dropping back, does it run the way you want it to? One thing is clear: sub 4000rpm the 3071 punches hard and really fills out total area under the curve.

After all that, if/when you have car down-time, the drilling/tapping operation into manifold or housing is quick and relatively easy. Use an NPT fitting and length of coiled bundy tube to dissipate heat, and a temporary pressure gauge will tell all.

Edited May 18, 2008 by Dale FZ1

[BHDave]

At this stage i don't mind working around the midrange hump. It seems to be something i will be stuck with until i go either a larger housing or external gate, neither option i can really afford for now. Boost can be held under 1.4bar now so I'm happy about that atleast, even though it means running less than 1 bar at the bottom end. The gate blowing open is an issue that only a tighter actuator can resolve, the concern then is whether that will push the midrange creep up beyond the 1.3-4bar it sits at now.

It's not falling back to the set pressure, it is generally falling to about 1 bar, whether it's set at that or higher.

Sub 4k it is making a lot more power than the old setup. I did a bodgy overlay last night, as all my dynos are plotted on the same scale so very easy to trace, and 4k is about where the cross over occurs. I'm about 20-25rwkw down for the rest of the run, though on road it doesn't seem to lack anything. The peak AFM reading is also about .25V down on where it used to be. I would like to get atleast 10 more kw up top to make this whole exercise worthwhile.

So who has a supplier for actuators? GCG seem to be a bit limited in that field. And who can give me some advice on a pfc boost control kit and how well it will handle this issue/what sort of tunability is there? I read the faq, it seems to be very basic (you set a target boost, but still have to muck about with a duty to get it to hold it?). Anyone have some thoughts or experience?

[Dragonforce]

Keep us updated how you go BHDave,

Following intently

goodluck!

["EN4CER"]

Do all gt3071 have boost trouble or just the unlucky few on different car setups?

[KISIN]

holy thread ressurection

rather then starting a new thread, ill stick it here.....

Still trying to decide what to get for an RB25. A real 3071r in .63 or .82 ??? IF anyone has a dyno graph of the .82 that they can post up, that would be awsome ! Seen the .63 earlier in this thread. When can i expect full boost in 2nd gear with .82 ?

Thanks.

Edited September 24, 2008 by KISIN

[BHDave]

have a look in the dyno results thread near the end for skylinecouple's results.

He's also posted in one of the other 3071 threads floating around

[KISIN]

have a look in the dyno results thread near the end for skylinecouple's results.

He's also posted in one of the other 3071 threads floating around

Thanks champ, just had a look...still not helping me decide lol. I basicly just want to be 100% sure i can can crack 250rwkw without much problems at all and have room for more (porbably a safe-ish 270)... .63 or .82 ?

Thanks.

[BHDave]

don't get a .63 internal gate housing. If you get ex gate .63 with a 44mm gate it will be an animal on an rb25. the .63 will just scrape in 270.

if you want to keep the stock manifold stick with a .82