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Discussion Starter · #1 ·
I have the following nipples that need vacuum lines run ... can someone chime in to help me out:

Wastegate: 1 on the top (post diaphram) and 1 on the bottom (pre diaphram)
Turbo: 1 on the compressor outlet
BOV: 1 on the top
Boost Controller Solenoid: 2, 1 on each side the solenoid
Boost Gauge: 1 on the back of the gauge.

Now, I know the one of the gauge goes to the controller solenoid, but other than that, I'm a little clueless.

So, how should my vacuum lines be run?
 

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1993 3000GT VR4
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block off the one on the turbo with a plug. you want all your readings from the manifold since there is gonna be some loss from the intercooler and piping.

you can run the wastegate and boost gauge off the same line from the manifold.

is the boost controller a manual or electric controller? with a manual controller you take the vacuum line from the manifold to the "in" port and then go from the "out" port to the lower nipple on the wastegate leaving the upper one open to atmosphere.
if its an electric one then you have to use both ports on the wastegate but i dont remember what the routing should be off hand.


Edit: this image is for a tial wastegate. im not sure what wastegate you have but i imagine its either a tial or something similar.
 

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you can run the wastegate and boost gauge off the same line from the manifold.
I don't think that's correct. You wouldn't want to run the wastegate line to the manifold. When you close the TB there can still be pressure after the turbo compressor. So, you want the wastegate line to go to the compressor outlet, but if you have an electronic boost controller you should connect the sensing line to the manifold.

Fastcougar, What kind of boost controller are you using? Did you get a manual with it?

This reminds me, has there been any discussion of using a PCV Valve that seals better than stock one. If not boost will leak into the crankcase and cause excessive air and oil blowing out of the valve cover breather. I think this has been discussed in the Zetec section. I have been venting my PCV to atm., but I'm going to switch to using a PCV Valve for a Cobra.
 

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Not according to Joey. he says in this thread only a little down the page how to setup the vacuum lines.

burritaSVT said:
I agree with the diagram except the wastegate because I can reach full boost at partial throttle so at less throttle the turbo will see more boost before the TB plate where the motor is less then the intended wastegate pressure.
cbman said:
When you close the TB there can still be pressure after the turbo compressor.
thats what a BOV is for :banghead:

cbman said:
his reminds me, has there been any discussion of using a PCV Valve that seals better than stock one. If not boost will leak into the crankcase and cause excessive air and oil blowing out of the valve cover breather. I think this has been discussed in the Zetec section. I have been venting my PCV to atm., but I'm going to switch to using a PCV Valve for a Cobra.
i am using a mustang PCV valve as well as a one-way check valve that i took from an extra brake booster hose i had. with the two of them get zero pressure going into the crankcase through the PCV system.
 

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post some pics to help
 

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Discussion Starter · #7 ·
I posted that diagram, but that diagram doesn't take into account a boost controller. Joey also suggested getting manifold pressure, NOT boost pressure for the wastegate.

I have a TiAL 38mm wastegate, TiAL 50mm BOV & AEM TruBoost Electronic Boost Controller/Guage. I will have to double check the AEM schematic. I was just hoping that someone knew how these should be routed. I just ordered the tubing, so I should have it by this weekend.
 

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Well, it looks like you can use a line before or after the TB for the wastegate, if you're using an electronic boost controller. However, after the TB is better if you are using the wastegate spring to control boost. That way boost in the manifold will go up to the spring pressure rating.

I'm using the Greddy Profec B Spec 2 electronic boost controller. (which BTW is a pain to setup) It has three lines COM, Normally Open, and Normally Closed. So, I'm not sure how the AEM works.
 

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Discussion Starter · #9 ·
Well, here is the diagram from the TruBoost:



However, I think taking the reading from the turbo outlet vs. the manifold cheats the pressure drop created by the intercooler. Therefore, I think it would be more accurate to do like the following diagram where 1 & 2 are tied into the manifold pressure, NOT the turbo outlet pressure. In this example, the turbo pressure port would be capped off.



Your thoughts?
 

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Thats how i would do it. that way all your boost reference points are the same. otherwise your gauge may say 12PSI but the AEM trueboost has to be set for like 14PSI.
 

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Discussion Starter · #11 ·
Well, I just got the following message from a user named TiAl on HondaTech:
tap the compressor housing for the boost source, you do not want the wastegate to see vacuum at all, and you don't want to over spin the turbo.

BOV should have it's own source off the intake manifold with 1/4in ID vacuum line minimum
While it makes sense, I could always tap the intake piping pre-throttle body to get a more accurate boost reading.
 

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Well, I just got the following message from a user named TiAl on HondaTech: While it makes sense, I could always tap the intake piping pre-throttle body to get a more accurate boost reading.
where you take your reference from isnt going to change weather or not you over spin the turbo. like i said before if you want 12PSI in the manifold the turbo is going to spin the same weather you tap into the manifold or into the compressor for your reference. youll just have to set the boost controller higher to if its tapped into the compressor. also there is no issues with the wastegate seeing vacuum, especially if there is a boost controller between it and the manifold (since the boost controller is closed until you hit a certain pressure anyways).

I still say tap into the manifold and set it up like the second one you posted.
 

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I have my wastegate connected to the manifold, sharing a line with the BOV and brake booster. My boost gauge reads 8 psi, so the wastegate appears to operate properly.
 
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