Another annoying GT35R question...

[95 TsiAWD]

I've got the PTE GT35RLS turbocharger
(4" 'S' compressor cover w/ ported shroud, 2.5 discharge)

The turbo is on a 1997 Mitsu GSX M/T mounted with the following mods:

Stock block and head
Turbonetics Cast Manifold with a Tial 38mm wastegate
Hallman Pro MBC
DSM Link
ND 720cc injectors (for now), w/ re-wired walbro 255 HP
Aeromotive FPR set at 43psi
Forced Performance 4" intake pipe
BJ's intake manifold
3" Throttle body
3" short route IC piping w/ spearco 2-216 core
3" turbo-back exhaust w/ hollowed out high flow cat
NGK BPR-7ES plugs and Dejon Coil-on-plug setup

vacuum line is connected to the side of the wastegate and i'm getting direct pressure from the intake manifold.

The car won't hold boost well.
I'm tryin to hold 15-16psi, but it always creeps to about 20psi

I have a friend with virtually the same setup as me, but he has a standalone with the MAF out.
He has the same problem as I do, but he can only hold the same boost as me with his exhaust silencer in. If he takes the silencer out, he spikes to 28psi.

A friend suggested to try a Tial 46mm wastegate to fix it, but I wanted to get more feedback before devoting $600+ (parts and labor) a trial solution.

Can anyone help us out with this problem ?

 

[definitiveno]

is it internal or atmospheric dump and what are the specs on your turbine?

 

[oldman]

Most boost creeps can be cured by porting the turbine housing, and I'm not talking about your reg. 50-90 port jobs offer by turbo vendors. There are specific areas of interest when porting to solve creep. Many on this board including myself have done it and there are many informative threads concerning this, do a search on boost creep and you will see. Good luck.

 

[95 TsiAWD]

Atmospheric dump

compressor specs: 82mm wheel, 56trim, .70 A/R
turbine specs: 68mm wheel, 84trim, .63 A/R

is it internal or atmospheric dump and what are the specs on your turbine?

 

[NDgsx]

Most boost creeps can be cured by porting the turbine housing, and I'm not talking about your reg. 50-90 port jobs offer by turbo vendors. There are specific areas of interest when porting to solve creep. Many on this board including myself have done it and there are many informative threads concerning this, do a search on boost creep and you will see. Good luck.

Port what? This is NOT a mitsubishi turbine housing with a flap door. It's a garret T3 housing with a external wastegate mounted on the #1 exhaust runner.

It may due to the wastegate only being off of one runner. I've run 16lbs steady using an SFP manifold on a customers 2G. He had the -14 cartridge that uses the GT30 turbine though. The turbine housing was also a .63.

What's wrong with 20psi?

 

[oldman]

Port what? This is NOT a mitsubishi turbine housing with a flap door. It's a garret T3 housing with a external wastegate mounted on the #1 exhaust runner.

My bad, didn't read it carefully enough.

 

[95 TsiAWD]

If I set boost at 20psi, it creeps to 22-23psi.

It pretty much creeps wherever I try to set it.

Port what? This is NOT a mitsubishi turbine housing with a flap door. It's a garret T3 housing with a external wastegate mounted on the #1 exhaust runner.

It may due to the wastegate only being off of one runner. I've run 16lbs steady using an SFP manifold on a customers 2G. He had the -14 cartridge that uses the GT30 turbine though. The turbine housing was also a .63.

What's wrong with 20psi?

 

[definitiveno]

Port what? This is NOT a mitsubishi turbine housing with a flap door. It's a garret T3 housing with a external wastegate mounted on the #1 exhaust runner.

It may due to the wastegate only being off of one runner. I've run 16lbs steady using an SFP manifold on a customers 2G. He had the -14 cartridge that uses the GT30 turbine though. The turbine housing was also a .63.

What's wrong with 20psi?

wow, you were holdin 16 on a 3040, in theory shouldn't he be able to run less boost with the larger housing?


Wastegate not opening properly?

 

[gasguzzler]

Do you have a picture of the exhaust manifold/wastegate set up? A wastegate will flow a lot better if you mount it at a 45* angle to the exhaust flow as compared to a 90* like many people do. It basically falls into the same theory as porting the turbine housing.

- Brian

 

[95 TsiAWD]

The Turbonetics manifold is designed to have the wastegate sit at about a 45degree angle.

Do you have a picture of the exhaust manifold/wastegate set up? A wastegate will flow a lot better if you mount it at a 45* angle to the exhaust flow as compared to a 90* like many people do. It basically falls into the same theory as porting the turbine housing.

- Brian

 

[95 TsiAWD]

Tried a new wastegate today... same problem.

Also tried mounting it on the turbine without prevail...

Any other suggestions ?

 

[definitiveno]

Nick, what size gate were you using on the -14?

 

[FourGdrvr]

Your wastegate is not expelling enough exhaust gas to control the boost. You can port the opening of the wastegate entrance on the manifold to help the boost control issue little bit, but you will probably want to change the manifold to something w/ external wastegate on the collector. You won't have to purchase 46mm tial wastegate. Run the newer Tial 44mm wastegate which has nicer v-band flanges if you can upgrade w/ a manifold.

Another idea would be drill a hole on the number 4 runner, machine the area flat, and drill and tap m8x1.25, and bolt on another Tial 38mm on the 4th runner, but this would be the econo ghetto method

The reason why your friend is able to control boost w/ the silencer in is because he is restricting the exhaust flow. Its a same idea as a guy w/ 16g + unported internal w/g + full 3inch downpipe, no cat, and 3 inch exhaust getting boost creep and another guy w/ 16G w/ 2.5 downpipe + cat getting no boost creep.

 

[damnthecops]

Which manifold would you suggest ?

There are only two manifolds that I know of that have the WG flange coming out of the collector and they are:

1) DN Performance which is stainless steel and comes with bracket support with a 1 year warranty against cracking

2) SFP manifold which is mild steel and comes with a 3 year warranty against cracking.

If you have any more suggestions... please make them.

Thanks for the space.

 

[tmizer]

If I set boost at 20psi, it creeps to 22-23psi.

It pretty much creeps wherever I try to set it.

The car won't hold boost well.
I'm tryin to hold 15-16psi, but it always creeps to about 20psi.

Considering the above symptoms and the wealth of decent mods, might it be as "simple" as the MBC hooked up with the lines reversed? Will hooking the intake line directly to the wastegate still net you 20+ psi?

Is the wastegate opening all the way? Remove the wastegate and directly attach a 20 psi pressure source to visually observe that the wastegate is opening ALL the way and not just cracking open.

 

[95 TsiAWD]

Considering the above symptoms and the wealth of decent mods, might it be as "simple" as the MBC hooked up with the lines reversed? Will hooking the intake line directly to the wastegate still net you 20+ psi?

Is the wastegate opening all the way? Remove the wastegate and directly attach a 20 psi pressure source to visually observe that the wastegate is opening ALL the way and not just cracking open.

The mbc is hooked up correctly and the wastegate does open all the way when a 20psi source is connected.

 

[FourGdrvr]

To test, first step you can take is remove the MBC, and run a boost source straight to the turbo, and run boost straight off of the wastegate spring. Check how much it creeps up to. The boost that you see on high rpm is gonna be the lowest psi u are gonna be able to run.

If the boost creep is tolerable, install the mbc, and try to set it to achieve that same psi as a steady boost (instead of creeping). Run the mbc vacuum line short and closer to the turbo if you are having trouble achieving steady boost.

If the boost creep is not tolerable, then change the setup as previously noted. Try it and post how the car responds.

 

[FireyIce01]

I can't seem to find the turbonetics manifold on their site, but I'm going to go out on a limb here... is there room at the collector to drill a hole at a 45 degree downward angle and tap it for a piece of steel pipe which could have a wastegate flange welded on the other end? Just a thought, instead of spending so much on a new manifold and this and that and the other...

...or you could put a full 3" cat in, which would probably give you enough exhaust restriction to prevent the spike, and not really hurt your performance as much as you might think.

edit

if it's anything like the cast evo or SBR manifolds, I'd put a wastegate hole right in the middle of the 4 bolt holes for the turbo on the top of the manifold, but you would then have to modify the heat shield to accomodate

 

[blue1]

If your manifold is not that old it should not hurt to do as you say with drilling and welding on a new wastegate mount, i think you should be able to get piping that will weld on ok. Best to talk will a reputable welding shop and they will suggest the type of pipe that will do the job and make the welding easier. good luck!

 

[red91gst]

What sping is in the Tial? Have you tried a softer spring?

The size of the wastegate does not seem to be the problem, the 38mm is more than enough to hold less than 20psi.

Nate
SBR

 

[95 TsiAWD]

What sping is in the Tial? Have you tried a softer spring?

The size of the wastegate does not seem to be the problem, the 38mm is more than enough to hold less than 20psi.

Nate
SBR

11psi spring

 

[95 TsiAWD]

I tried putting the wastegate on the turbine side of the turbo.

This way I would be pulling evenly from all cylinders. I would think...

Wouldn't this have the same effect as mounting the wastegate collector on the exhaust manifold ?

This attempt did not solve the problem.

 

[FourGdrvr]

did you drill a hole on to the turbine housing, and weld a flange on the turbine housing for the tial 38mm w/g?

 

[95 TsiAWD]

did you drill a hole on to the turbine housing, and weld a flange on the turbine housing for the tial 38mm w/g?

yes

 

[HighPsiAwd]

wow, you were holdin 16 on a 3040, in theory shouldn't he be able to run less boost with the larger housing?


Wastegate not opening properly?

That was my setup he was speaking of. We could run less boost, Nick was just saying that the boost held rock steady at any level with no creep. I am currenly running no mbc and it holds rock steady on the 9lb wastegate spring.

Nick, what size gate were you using on the -14?

Turbonetics Evolutions 38mm