garrett 3076r maxed out at 27psi?

[linjy2]

So I tuned my car this past weekend on E85. Good news is I think I am the first person to make this # on this specific turbo and posted about it.

I have:

Garrett 3076r bolt on
uicp
fmic
intake
forge actuator
o2/downpipe
testpipe
catback
synapse synchronic bov
hks evc 6
1000cc
walbro
e85

Made 456whp and 380wtq at 27psi in 70 degree weather

Made 440whp and 386wtq at 28.5psi spike in 78+ degree weather

Now my question is. I really wanted to run 30-33psi this weekend but couldnt boost higher then 27psi. My tuner and everyone else was anticipating some 30+psi action. It seemed like right when I hit 27psi it just stops there.

I did a boost leak test and found the stock bov leaking pass 27psi, it wouldnt hold any more. So i swapped in my buddies synapse bov. holds to the 30psi that i wanted to run and more.

We decided to go out and retune again since the boost leak were fixed. still no go. It basically hits a wall at 27psi. Any idea on what would be causing this? any other way to determine why? i dont think its a faulty ebc cause we swapped to a mbc and it maxed out at full turn to 27psi also..

I'm just starting to think this turbo is at its limit? I was hoping to hit 480whp+

[sne2040]

is there enough fuel? e85 + that much boost on a 30R, possibly the fuel system being maxed out?

[linjy2]

fuel is not maxed out.. was only 70% idc give or take.

alot more to go..

[flyboytb]

congrats on the numbers. post up a graph i wanna see how this beast spools.

[linjy2]

Originally Posted by flyboytb

congrats on the numbers. post up a graph i wanna see how this beast spools.

hopefully my tuner will post a graph soon.

It spool around 4krpm i think, i haven't drove it much yet since it rained after the tune.

there's more power up top, so i definitely need some cams and springs to rev it to 9krpm.

[Hiboost]

Those are nice results! What kind of numbers does a stock Evo X lay down on that particular dyno and what crank HP do you think it's laying down? My spoolup was 20 psi by 3600 in 4th starting at 2000 rpm's and full boost was usually hit around 3800-4000 depending on load.

On the internal wastegate I was able to easily run as low as 17 psi with no creep and had to preload my Forge WGA to 6 turns in order to get a base boost of 24 psi. Once I added in my MBC I could get the car to boost as low as 25 psi holding to around 7200 and then it would drop to about 23 psi @ 8000. With the car set for 27 psi it would be at 26 psi by 7200 and then drop to 24 psi @ 8000.

About a month ago I tested 30 psi on 100 unleaded and it gained about 30-40 ft lbs of torque down low, but then had the same boost falloff to 26 psi at 7200 and drop down to 24 psi @ 8000. I've noticed other stock framed turbos like the FP Red and Dom 2 have a similar boost falloff at higher RPM's. I'm not sure if the engine isn't allowing the flow or if the turbo really is "out of flow". It could also be the internal wastegate being a bit too efficient at higher RPM's and the WGA can't fight all the backpressure to keep the boost at the set point.

Recently my Interal Wastegate flapper decided to break off and go flying down my exhaust so now I'm at about 3 psi boost... since there are no replacement turbos easily obtainable I decided to get an O2 Downpipe that has an integrated Tial 44mm External Wastegate. We'll see if this allows boost to hold better above 7200 rpm and I plan on turning up the boost to 32-35 psi on 116 octane race gas to really test the limits of this turbo. Mods after that will be a modified Intake manifold with larger internal volume (it's done but needs to be tested) and likely Cosworth MX1 cams.

With the turbo off the car I'll likely port the exhaust side for better flow where it counts which should help the top end power with minimal risk of losing spoolup or response. Honestly I was already getting some compressor surge if I went WOT in 5th and tried to boost over 20 psi at 3400 rpm's so trading some response for top end power would be ok.

Hope that gives you another data point on your turbo setup!

[itznoraa]

^^ the thing is, we couldnt get it to spike past 27. That was alot of helpful info.

[linjy2]

actually those are only dll #s, i'm not getting a real dyno till mid nov. waiting on dyno day here.

Maybe I should of turned my wga more to see if i could boost higher. i might try that sometimes this week. But then it would mess up my tune. i think i taper to 24 then 22.

i'm most likely going with that steedspeed ewg manifold once its released, so i will try to push this turbo further sometime next year. i cant wait to see ur results on 32-35psi, thats what i wanted but just couldnt hit it this time around.

[GST Motorsports]

Something is leaking if you can't get past 27psi.

I've run one at 29psi, then it blew up. So YMMV.

It also won't make a ton more power like a proper garrett will with more boost.

- bryan

[spdracerut]

Originally Posted by Hiboost

About a month ago I tested 30 psi on 100 unleaded and it gained about 30-40 ft lbs of torque down low, but then had the same boost falloff to 26 psi at 7200 and drop down to 24 psi @ 8000. I've noticed other stock framed turbos like the FP Red and Dom 2 have a similar boost falloff at higher RPM's. I'm not sure if the engine isn't allowing the flow or if the turbo really is "out of flow". It could also be the internal wastegate being a bit too efficient at higher RPM's and the WGA can't fight all the backpressure to keep the boost at the set point.

Chris, I think there are two factors relating to the drop in boost: 1. you're near the flow limit of the wheel as is 2. All the stock frame turbos are limited by the inlet elbow into the compressor. That becomes more of a choke point the higher the power gets.

I saw that ATP has that 3" inlet for the Garrett turbo which should help flow. I don't know how much it would hurt surge though. You might be able to tune around the surge though by altering your cam timing; or course, tuning 'around' surge just means you're reducing the boost pressure at a given mass flow point.

[linjy2]

Originally Posted by GST Motorsports

Something is leaking if you can't get past 27psi.

I've run one at 29psi, then it blew up. So YMMV.

It also won't make a ton more power like a proper garrett will with more boost.

- bryan

yea.. i think the last thing could be my gasket as i reused every single one. and i took the turbo, o2.downpipe, and manifold off like 4 times and reused.

thanks for ruining my hopes of boosting higher.

i bought this turbo when it first came out and pretty much just had it sitting there for 3 months before installing it. mainly due to poor results and everything. still ended up installing it because i couldnt return it anyways.

[spdracerut]

Originally Posted by itznoraa

^^ the thing is, we couldnt get it to spike past 27. That was alot of helpful info.

The Forge is adjustable isn't it? Add in a half turn of preload and see what it does.

[Hiboost]

6 turns gained me 6-7 psi base so 1/2 turn won't really show up very well.

Something is leaking if you can't get past 27psi.

I've run one at 29psi, then it blew up. So YMMV.

It also won't make a ton more power like a proper garrett will with more boost.

- bryan

Ouch Bryan, I think I read about that blowup sometime before. It does seem like 27 psi on pump gas is about the best case scenario for this turbo although the low end torque was borderline rediculous at 30 psi and 100 unleaded. We will see if the external WG allows boost to be held all the way to 8000.

Chris, I think there are two factors relating to the drop in boost: 1. you're near the flow limit of the wheel as is 2. All the stock frame turbos are limited by the inlet elbow into the compressor. That becomes more of a choke point the higher the power gets.

I saw that ATP has that 3" inlet for the Garrett turbo which should help flow. I don't know how much it would hurt surge though. You might be able to tune around the surge though by altering your cam timing; or course, tuning 'around' surge just means you're reducing the boost pressure at a given mass flow point.

Hmmm so is the intake or exhaust wheel running out of flow first on a GT30? I guess if mine blows apart I'll consider either a full ETS kit or get the turbo rebuilt by Forced Performance and use the latest GT35r wheel combos.

When you say Inlet elbow to the compressor that is the 45* piece leading to the MAF? It does seem that it could be a restriction, I may look into an ATP piece that replaces that part then. I should be able to dial back MIVEC settings in the 3000-3500 area to avoid surge in case it gets any worse. So far it only happens in 5th gear so as long as WOT in 4th never triggers the compressor surge I'm happy.

What are all the people with GT35 turbos doing for intake piping? I would imagine a 3.5" intake pipe would be better, you would just have to tune the MAF compensation tables a bit to get the car running smoothly or the sensor would be pretty far off.

[ETS Michael]

What MAP sensor is on the car? Is it breaking up at 28psi? If I remember correctly, the stock MAP sensor is only a 3 bar map sensor. You might want to switch it out for an OMNI 4 bar map sensor that is plug and play. If it's not breaking up, you might need to check for leaks.

Michael

[GST Motorsports]

Mitsu 3 bar is good to about 32-33 psi