I am have another FRICKIN problem now !!! , I decided to tune for 15psi WITHOUT my boost controller and Water injection system on line .
I leaned out my a/f ratios to mid 11 's and the car started to pull real hard !!! , by 5000 rpm I had 12psi , by 6300 I am at 16psi and at 6400 it spiked streight to 20.6 !!!!! , my wastegates are set to open at 12 psi !! , what de HELL GOIN ON NOW ??? !!!.
Previously I tuned up to 15 psi (before installing the twin '044's) at 8500 rpm 's without any problems , the only significant thing I did since then was having the turbo re-balanced (the supplier said that they had found a massive imbalance in the turbo ) , could this be causing the turbo to spin up faster and push more air ??
I opened up both waste gates , both diaphragms were in excellent shape , I also pulled both gates and checked their operation , both opened up wide when pressure was applied under the diaphragm .I think I may have to go to larger ones , like two 48mm ones , what ya think guys ?.

 

I have only been reading your posts off and on. But what compressor turbo are you running? And what WG's do you have now?

I can see anyone needing that much WG. I'm running dual Tial 38mm gates and I have stable boost without creep around .8bar. Granted I'm "only" running a T04R compressor(66.7mm inducer on the compressor), which I know is smaller than yours.

It could be your WG positioning that isn't allowing proper airflow out of the mani.

-Chris

 

Can anyone way setzep ?

I would lean towards positioning and flow path into the WG after reading his experiences.

then again 20.6psi is not to high Marcel

 

No not too high , but I want some control and I want to be able to rev the **** out of my motor !!

 

What does your exhaust manifold look like now?

What diameter are the runners and what diameter are the wastegate pipes?

Do you have any pics of it?

 

I dont have any pics of it , and its a bit hard to get at now , but the runners are fairly long , placing the turbine side just where the air pump used to be ,they are 2" in I.D. . the pipes to the gates are 1.5 " I.D . and come off the headers at different points.
What I can't understand is , the fact that it worked great before , nothing has been changed in my set up that would have a direct effect the gates . the only thing is the rebalancing of the turbo.
I plan to try disconnecting the exhaust pipe from the gates to the dp. and have them dump to atmosphere and see if that would make a difference.

 

Below is a bit if info. (a bit long ) I found on the Tial web site , after reading the " mounting " section , I realize that I may have to modify mine to coax the gasses to flow since the wg runners were welded at a 90 deg andgle to the headers .




Which wastegate do I need?


Selection of the correct size/model wastegate is dependent upon several variables.

Bolt in compatibility.
The 38mm and 46mm gates are made to be direct bolt in replacements for existing wastegates as well as custom setups. The 38mm gate is dimensional equivalent to the Turbonetics delta gate with many features not found in the delta gate. The 46mm gate is a drop in for the 930 Porsche turbo cars.
Flow capacity.
Contrary to popular belief, larger higher HP applications do not necessarily require the largest wastegate available. The lower the boost pressure you are gunning for the larger your wastegate needs to be. An engine/turbo combination that is set to 25+psi has a smaller wastegate flow requirement than the same application set to 7 psi. This is because the wastegate is used to lower the boost not raise it, the lower the boost pressure is set the more flow the wastegate must allow.
The spring.
TiAL wastegates are not adjustable. To change the boost pressure at which the valve opens requires changing the spring within the wastegate. Springs range from .3 Bar to over 1 Bar are available. The most common way to select your spring size is to pick a pressure rating that is a couple tenths or a bar or a few psi lower than the boost pressure you intend to operate the turbo/engine combo at. This way a boost controller can be used to adjust the opening point of the wastegate and help you fine tune to the exact pressure that is desired. This also allows adjustments to compensate for changes in atm pressure, altitude and temperature, which will all effect the way your wastegate does it's job.

Mounting the wastegate.
This is one of the most overlooked areas of boost control. In a perfect world you would select a mounting location for our wastegate that allows the gate equal access to all cylinders or rotors. This promotes equal exhaust port pressures between cylinders/rotors and avoids mysterious tuning problems resulting from uneven exhaust port back pressures. Another aspect to keep in mind is the high velocity of the exhaust gas inside the exhaust manifold, sometimes exceeding 800ft sec. Gas that is traveling at such high velocities will not easily make 90 degree turns of zero radius into the wastegate inlet. Remember Newton's second law, "bodies in motion tend to stay on motion". That particle of air is not particularly inclined to make a 90 degree turn and 800ft/sec. It must be persuaded to do so by giving it a gentle radius and easy access to the exhaust flow. Simply welding the gate to the side of a tube may work in some cases where the manifold back pressure is thru the roof, but in modern high efficiency turbochargers the pressure inside the manifold can be quite low and special through should go into wastegate runner geometry. The penalty for poor gate placement and poor gate runner design is having to use a larger gate.

 

It looks like you stole that from the TiAl webpage...

 

What are your methods of boost controlling besides the wastegate? Your turbo supplier said there was an imbalance? Could you explain that more? Fixing an "imbalance" problem shouldn't cause the boost the spike. I don't think the wastegate is the problem.

 

An imbalance was found in the CHRA (the rotating assembly) and corrected , so I'm thinking that because the turbo is now performing more efficiently ,its producing more boost faster or lower in the RPM range.
I have an electronic controller , which I thaught was unable to control the boost 'cause of its single "small" solenoid valve , (it seems that I may be wrong) , it by the way , isn't connected to the gates I just use it as a boost gauge for now, the gates are connected directly to the pressure source on the turbos discharge.

 

The problem is still pretty vague to me. It can't be the turbocharger. Getting larger wastegates aren't going to solve the problem. Why did you set the gates to open at 12 psi?

 

The 0.8 bar (11.6 psi ) spring was the only available one at the time.

 

Are there any other options for the wastegate spring you have?

 

Yes , but that isn't going to help since both gate are actually going WIDE open before I actually reach to 12 psi. , I know this because I removed them and tested them with less pressure and they responded .
I honestly think that it may be the placement of the "bleed " points on the manifold.

 

What angle do the wastegate pipes come off the runners?

I had a similar overboosting problem when my wastegate pipes didn't flow in the same direction as the runners on the manifold. I have since changed the manifold and the boost is now steady.

 

this is exactly what I am thinking , my wastegates pipes are welded at 90 degree angles to the main runners , so the exh. gasses would have to make a sharp 90 deg. turn to flow into them . I am thinking also that because of the size of my turbine ( 68mm wheel in a 1.22 housing ) and down pipe (3.5 ) , the pressure inside my manifold doesn't get that high , so I would have to rely on proper FLOW rather than PRESSURE to get the exhaust to leave the manifold and pass through the gates.
I dont want to redo my manifold , so I'll just cut off the existing w.g pipes and cap the holes , then put in new pipes in locations that will maintain the streightest flow paths possible , from the manifold into the w.g. pipes .

 

Thats what I did too. Keep us posted on if it works or not. I also increased the size from 25mm pipes to 40mm.