T3/T4 FP3076R 0.63 A/R - Overboosting problem

[zdrux]

I would welcome anybody who either HAS or HAS had a problem of this nature similiar to what I`m experiencing with simliar parts on their car.

The turbo I have is a GT30R from FP *BUT* with the smaller 0.63 A/R turbine housing. The problem started when I first put the turbo on. I had some tubular manifold and a 38mm gate. The boost would hold fine up to about 5.5k rpm at which point it would start rising and eventually end up at 24-25psi by 7k rpm. Since the manifold wasn't the highest quality and the routing to the wastegate wasn't as smooth as should have been I have placed my problems on thinking that it simply wasn't re-routing enough exhaust out the wastegate.

So I went out and bought myself a brand spanking new DNP t3/t4 manifold AND a 44mm Tial gate just to be sure there won't be any future problems. I put it on, but to my dissapointment it turned out to only help the problem a little bit.

The boost will still spike to 22-24psi which is a little lower than the previous setup, and also spikes a bit later 6-7k rpm, but regardless - it's still there which makes me unhappy because it makes it hard to tune properly not knowing what it`ll spike to, and also not being able to run only 17-20psi, thus not allowing me to fully use all the timing up top. I have to take out alot of timing just so it doesn't knock at 24psi.

I have gone throught all the typical stuff, remove MBC alltogether, checks for leaks, stuck wastegate, wastegate diaphram, etc.. so I`ll spare you guys the trouble and let's get down to the real problem. Does anybody here believe the housing is to blame? I have a pretty much full-blown setup with 272's 9:1 pistons, big injectors, etc..

I have a feeling that I`m at a stage where the car is able to outflow the turbine side causing excess back-pressure in the manifold over-spinning the turbine even with a 44mm gate, can someone prove/disprove my theory?!

I have talked to SBR about getting a pricing on a new Garrett 0.82 A/R turbine side, but they said even with a 38mm gate I should be able to control boost, but I`m not so sure they're so right on this, has anyone come across this?

 

[dsm-onster]

I have a feeling that I`m at a stage where the car is able to outflow the turbine side causing excess back-pressure in the manifold over-spinning the turbine even with a 44mm gate, can someone prove/disprove my theory?!

You're talking about "exhaust lock". Guys w/ more have not done this on this hot side.

You have a .63 hot side w/ a higher flowing turbine than a TD06H wheel. Straight from FP:

FP3052
The GT30 turbine wheel is smaller in diameter than the Mitsubishi TD06 and TD06H turbine wheels but flows far more, allowing greater boost pressure without unfavorably high ratios of exhaust to intake pressure. To put it simply, the intake manifold pressure stays higher than the exhaust manifold pressure under a wider range of operating conditions. This is good.​

No way you're out flowing it. There has to be something else wrong...

For what psi is the wastgate rated?
Have you talked to FP about this? They would know more about their turbo than anyone.

 

[95 TsiAWD]

If you're running a full Garrett GT30R and not the FP3052, I think I might have the answer to your problem.

A customer of mine went through the same problem as you have, and I went crazy trying to figure it out. He has a full Garrett GT35R turbocharger with a .63 a/r 5-bolt exhaust housing mounted onto a Turbonetics T3 cast manifold with a Tial38 mounted on the #1runner.

With a Tial 38mm external wastegate (.8bar or 11psi) with no boost controller hooked up, we expected the wastegate to hold 11psi with no problem. BIG MISTAKE. The car wouldn't see anything under 17psi, but spiked to 22-24psi at anything rpm over 5500.

What we did to fix the problem was:

1) bought the tial 38mm wastegate blockoff plate from ATP and put it on
2) bought a new turbine housing for the turbo (.63a/r, 5bolt) setup for an internal gate.
3) bought a Tial 46mm wastegate
4) ported the wastegate hole on the new turbine housing as best I could to match the Tial 46mm flange.
5) made a custom 2.5" tubular 02 housing so I could mount the 46mm Tial on it.

After all of this was done, the car could hold as little as 11psi and as much as 24psi (so far) with no creeping whatsoever.

What the problem was... was that the wastegate was mounted on the #1 runner on the Turbonetics manifold and was not pulling air from all 4 cylinders evenly. Mounting the wastegate on the 02 housing was the only way that I thought would work and it did. Forced Performance's turbine housings is what inspired me, their housings have v-band outlet so you could throw on a 44mm Tial with no boost problems.

My "fix" will only work if you do have a 5bolt turbine housing on your turbo. If you have a 4bolt, I wouldn't know what to tell you except to try getting the 44mm-to-46mm adapter from DNP, buy or borrow someone's Tial 46mm wastegate and pray to get it works.

Hope this helps. Good Luck

 

[zdrux]

This is certainly not good news. I have a 4bolt outlet housing and yes the turbo is a Garrett GT30R from FP, but the DNP manifold should have enough flow to relieve enough pressure, at least I thought it would... I really don't want to go with a bigger wastegate because I have never seen anyone who needed one this big for this sort of setup that I have. I`ll try sending FP and email or calling them, I just wish there was a simpler solution to this than once again buying more stuff.

 

[95 TsiAWD]

What type of boost controller are you using ?

It could be as simple as that.

 

[zdrux]

What type of boost controller are you using ?

It could be as simple as that.

No boost controller. Boost source straight off intake manifold. I`m going to remove the spring out of the wastegate to make sure it's not the wastegate in anyway, just to remove that out of the equation (...or not). If it still boosts, then I`m sure it's the manifold/gate setup and not something else.

 

[OB1]

It could be compressor surge if you are using a TO4E compressor cover and not the anit-surge TO4S cover.

 

[T2Small]

Are you dumping the wastegate gasses to the atmosphere, or are you running them back into the exhaust? If you have a restricted exit for the wastegate gasses I could see a combination of only dumping runner #1 and the wastegate gas restrictions causing your problems.

I would be really interested to see if you solve your problems. I am seriously considering a DNP manifold, 44mm gate, and a surge ported GT3076 for my built 2.4. If you can't solve your problems I will stick with a real FP3052 and forgo the DNP manifold.