i can't run low boost like i want, i have the turbonetics MBC running to my dual Tial 38mm wastegate, the top nipple is vented back into the UIM. When i vent the top to open it boost 1.5+ bar, now when i route it back the way it was before im getting like almost 20psi. i only want like 16psi.
The twin tial 38mm is running on 8psi spring, and i got a Greddy type R blowoff valve. what do you think it is?, I recently replaced all the lines on the turbo and warped it with 2000F heat resitant insulation to keep it from baking and cracking.

do you guys think its the MBC, should i get a better one like the hallman? im also getting different boost , like 3rd gear boost higher then 2nd or 4th, same run just different gear.

any help would be appreicated.

 

BTW, yes the MBC is all the out , maybe a 1/4 to 1/2 in, with it all the way out (baiscall off) im getting a little over 1bar.

 

Why don't you just get new springs from tial for the wastegates and throw the boost controller in the trash?

Also why are you running the upper port to anything, shouldn't that port be vented to the atmosphere?

 

i tried venting it and it boost 1.5bar + with the controller off, thats with and 8psi spring in both 38mm waste gate, i hook the top to the UIM to lower the boost.
with the 8psi pring i doubt going lower would help any, any other ideas?

 

What I meant for the springs was getting the 14.5, 16 or 17.5 psi spring setup and then just using the springs with no boost controller.

You say that you are hooking the top port to the upper intake manifold to lower boost, that seams counter to the purpose of the upper port. The upper port is there so that you can apply air pressure to the same side of the diaphragm as the spring so effectively INCREASING the pressure rating of the spring.

Are you sure that all of the plumbing for the wastegate(s) is correct?

 

yep..
line out from the controller is T off to each of the side of the wastegate, then the top is T to the line to under the UIM. if i remove the top wastegate then it boost really high. again i varified with the previous owner that the dual 38mm wastegate has a 8psi spring.

 

In your last post it sounds like you have it routed correctly. Instead of going to the UIM for the pressure signal tap into the compressor housing. What happens if you run without the boost controller? As in sideports of the wastegate to the compressor housing, and just vent the top ports to atmosphere.

http://www.tialmedia.com/documents/w..._wginstall.pdf

 

What he said, run your gates with no controller, just using the the side port on the gate, and get your reference signal off the comp cover, then see where your at.


~S~

 

did that, ran it with the controller off and a solid line with no controller to each side port and open top, 1.5bar.

this morning i ran the lines per tial instruction, like out of the cold side of the turbo "T" to side wastegates, line after the MBC to the top waste gate, only getting .6bar. controller seems to have no effect when i turn it up so now im trying this.
Install as per tial instruction but with a twist. line out from the cold side of the turbo to the MBC, line out from the MBC to the top and side of both waste gate, now it only goes to .7 bars with the controller off so its better IMO to have lower boost then to overboost, but there is also no creep , it holds solid at .7 and i can hear the wastegate dumping out. so im going to stay with this set up and asjust the controller, seeing if i can get more boost by turning it up, basically if i can get 1.2bar or 16psi then im happy.
I just think that if both the top and side wastegate gets the pressure after the boost controller has done its job controlling it then it should make better sense then having the side wastegate getting the full boost pressure before the MBC has doen anything, and only the top get the signal from the MBC.

If you look at the diagram below, basically what i did is where you see the instruction say to "T" the line from the top of the wastegate to line out of the MBC, i "T" that line to both the side and top of the dual wastegates, giving both top and bottom positive pressure from the boost controller.
Will keep you guys updated, so far i think in the right track.

 

oh one more question..
do you guys run the line out from the cold side of the turbo to the manifo and get the boost signal to the wastegate from the BOV line (the lines that from the top of the manifold on the passenger side), then the line from the cold side of the turbo is vented back into line that goes inbetween the block and UIM (basically where the fuel rail is)...
has anyone hooked it up like that?

Like this:

 

Ok got it firured out, holds stead at 1.2bar according to the Greddy boost guage taped into the UIM, and 1.05bar according to the PFC commander.
Here is how i routed the line.

The line comming out of the turbo, cold side right under my filter is "T", one going to the boost controller and the other T goes to the side of each one of my wastegates. The line coming out the other side of my manual boost controller is then "T" off to each of the top vent of the wastegate. This setup hold steady boost for me, no creep or spike, holds 16psi from around 4.5k to 8k.

My mods are:
Large Gotham Racing port
550 prim 16002ndary injectors
dual supra fuel pump with 14v wire mod
Garett GT43 1.15hot side
Equal length manifold with dual 38mm Tial wastegates
Greddy type R BOV

those are the basic engine mods, hope this help if anyone with a similar setup is having boost problems.

Tony