Turbo too laggy - GT3076R on 3S-GTE

[Cuts]

he bought it as a kit already, someone else made the error. I suppose they first used internal gate and found it didnt control boost well enough so they chucked the external on.

Ide do what woggin said and try to wire it one way, if there is improvement then the issue could be there.

Also the issue could be with the internal gate flap itself, prehaps its out of shape/got a nick in it stopping it closing properly etc.

[mr2mark]

Can you work out if it is a 'real' gt3076r as per http://www.turbobygarrett.com/turbob..._700382_12.htm
or if it is some custom setup?
Internally gated gt30 series turbos Ive heard of can be gt30 turbine wheels modified to fit t25 style housings. They seem to turn up as bolt on turbos in stock t25 flange cars like sr20's. Unfortunately they lack turbine efficiency and if you had one of these it would explain some laggyness.

[MWP]

There is no need to weld it shut.
Wireing it shut securely is enough, and doesnt ruin its resale value if it doesnt fix the problem and you do want to downgrade.

I imagine you are running an aftermarket ECU of some sort?
Are you sure the tune is good?
Having a bad tune will effect turbo lag.

[TRDcelica90]

Ok update..

took the turbo off and had a look. i was mistaken when i said that the internal wastegate was still in there. it had been removed and the outlet was pointing to the external wastegate.

also checked the part number and the A/R of the exhaust housing is indeed a .84 trim.

MWP no aftermarket ECU yet, got an E-manage waiting to be installed with 540cc, thats why im running low boost atm..

so my question now is. when should i start seeing boost and when should i get full boost with the .84??

i may have found an air leak before the turbo so im sorting that out atm.

also gonna try changing the port the vacuum comes from with the external gate. it was blocked off, maybe toyota did that for a good reason?

[jonathan yee]

pics?

i'm confused as to how the "internal wastegate was removed and the outlet is pointing towards the external waste gate"

you can't remove the internal waste gate and direct it anywhere. you just remove it and then block it off/weld in a core plug or something to that effect.

[Cuts]

im going to assume the extrernal gate gets its flow from the internal gate port???

.84 ask 71MEH, he had a .84 on his 3076, i seem to remember he didnt have 20 psi till like 5000rpm or something.

by comparison my larger turbo (larger compressor) but smaller (.63) zaust housing gets 20+psi by 4000rpm.

[mr2mark]

The 'real' gt3076r only comes in .63 .82 and 1.06 as you can see here http://www.turbobygarrett.com/turbob..._700382_12.htm

I suspect you have some sort of hybrid/custom turbo and/or one of the t25 based ones? If so, the mismatched wheels are a likely culprit of worse than expected lag.

[mattysshop]

i think you should fit the external gate directly to the manifold where it is ment to be.. and weld/bung up the internal gate setup...

or piss the external gate off.. and get the internal gate functioning properly..

either way the setup needs to be correct internal or external..

[Shifty]

Hi mate

Firstly, the 3SGTE and GT3076R is a formidable combo, capable of 300kwatw any day of the week. However, it looks like you need to understand more about turbos and more specifically your turbo setup. That said, there are no critical flaws with your system as long as the internal wastegate can't open (either wired hard shut, or welded shut).

Secondly, you need to understand that this turbo is not EVER going to be responsive on a two litre. Don't EVER expect positive boost at 2200rpm. This is a BIG turbo and it's designed to make BIG power on BIG boost. You will NEVER be happy with this turbo on 10psi. Even at 17psi that you mentioned, this turbo still isn't really working hard. I haven't had a look at the compressor maps but generally I'd expect this turbo to operate best at 20-22psi. If you're running it at less than this, you need to (a) get it tuned for more boost, or (b) change to a smaller turbo that suits your power goals more appropriately.

The figures you've mentioned, while they can use some improvement (through changing exhaust housing, manifold design) probably aren't far from real world results you can expect with this turbocharger. Here is a dyno sheet of a GT3076R on a 1.8lt engine. I know you have a 2.0lt engine but in the real world your sheet shouldn't be more than a couple of hundred rpm different to this. As you can see it makes literally nothing down low. Also, this is only running 13psi. At 10psi you mentioned I wouldn't expect too much more than 200rwhp and at that 17psi you mentioned I'd expect you to be in the low 300rwhp range. This turbo is completely oversided and utterly wasted at this power level. Those power levels are achievable on something like my turbo, a GT28R.

I have over 250rwhp+ at ~15psi but am well and truly making positive pressure by 2500rpm.

the turbo builds boost very slowly up till 3.8ish RPM.. then by about 4.2 will pull hard the whole way to redline with little effort.. im only running 10psi but takes WAY too long for the boost.

This is about right, in my opinion. This turbo is designed to hit hard in the midrange and pull all the way into the top end.

Im looking for as much response as possible with this kind of set up. My thoughts are changing to a small exhaust housing. what is the cost and effort involved with this though??

I would look at a twin-scroll T3 housing. You can get one that will bolt onto your turbo and manifold, but you may need to change the plate on your dump pipe. If you need to buy one new you could be looking at an easy $400 + labour but if you gegt one second hand off a forum and can do it yourself you may only pay $100 and DIY obviously no labour.

i dont plan on putting more the 17psi through it for a fair while.

You have the wrong turbo if you are only running 10psi, or even 17psi. Any mid-to-large late model turbo is wasted at anything less than 18-20psi.

Also there is a lot we don't know about your setup.

What cams are you running?
What is done to the engine & what condition is it in?
Have you got a dyno sheet?
What is the tune like & was it done by a professional?
What did they have to say about your setup?
What boost controller are you running?

[mattysshop]

as shifty said there are plenty of turbo's that are better sutied that would make good power and response..

my mates built 3sgte is only running a small GT28R.. at 15psi makes 252fwhp, and a broad muscular torque band right from about 2200rpm (boost is about 3-4psi) which is what you would want for such a heavy car like the 185..

granted that little gt28r is almost at it's limit with a little more boost (the rear housing is quite small for top end).. but the GT28RS is slightly bigger and you can get a few different front and rear covers.. for the T2 /T28 platform...

all of this though would require a new manifold, and dump pipe..

[Joshstix]

I suspect he actually has a manifold with a T2 flange on it if he has an external gate that is plumbed into the turbine housing via the normal internal gate passage.

[Cuts]

he is still running the stock cams,ecu, internals afaik.

[Shifty]

well for a start, this turbo needs cams

[SillyCarS]

shifty is the fuckin man

[mr2mark]

I would look at a twin-scroll T3 housing. You can get one that will bolt onto your turbo and manifold, but you may need to change the plate on your dump pipe. If you need to buy one new you could be looking at an easy $400 + labour but if you gegt one second hand off a forum and can do it yourself you may only pay $100 and DIY obviously no labour.

The pictures he posted above show a custom exhaust manifold and it looks like there isnt any split pulse to me. To run a true twin scroll with a external wastegate you need 2 wastegates (1 for each pulse) anyway. Even if the split is extended all the way to the diaphragm of a single wastegate, the effect is much diminished.
IMO, twin scroll (with external wastegates) should be included in the design of a custom exhaust manifold from the start.
Ive been looking on and off for twin scroll t3 housings for ages so I can one day (time and money permitting) make a new manifold and downpipe setup for my gt3076.