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Why Was My Gtr On Unlimited Boost?

druzilla32

By druzilla32,
in Forced Induction Performance

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oRiCLe Rising Star

oRiCLe

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standard boost when it is disconnected because it has a bleed on the vaccuum line that feeds from the engine after the solenoid that prevents it from overboosting if the solenoid fails/disconnects, i had to install my boost controller on the turbo side of my engine after the solenoid and the vaccuum feed, just before the wastegates. i think i remember reading the t-piece that feeds the line is between the head and the firewall...round the back of the engine...

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GTR-Ben Proficient

GTR-Ben

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standard boost when it is disconnected because it has a bleed on the vaccuum line that feeds from the engine after the solenoid that prevents it from overboosting if the solenoid fails/disconnects, i had to install my boost controller on the turbo side of my engine after the solenoid and the vaccuum feed, just before the wastegates. i think i remember reading the t-piece that feeds the line is between the head and the firewall...round the back of the engine...

Wrong. You disconnect the stock solenoid and leave the pipes open it will FREE BOOST.

It's simple.

There is a T under the back of the plenum. It T's 1 to the wastegates, 1 to the solenoid. Now if the solenoid failed.. my guess would be it would stay closed which would give you stock boost.

You remove the solenoid however you are now BLEEDING air from the wastegates, and we all know what you get when you bleed air away from them.. a boost increase.

Now the other end of the solenoid simply bleeds air back to the intake pipe. (for emissions etc)

To install a boost controller in the stock position, you need to block the pipe right at the rear of the plenum (the T), and run a new pipe from where it was connected to the plenum. This is the pressure feed. Now the stock line that goes to the solenoid has a direct connection to the wastegates (because you have blocked of the T into the plenum). This can be checked by putting some air down the line and hearing the wastegates open and close.

You block the feed to the intake pipe.

I think people need to get a engine up on a stand, follow all the pipes and make a drawing or something so they can understand how it's all linked.

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oRiCLe Rising Star

oRiCLe

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i may be wrong but even i have disconnected it completely and run stock boost...

There is a T under the back of the plenum. It T's 1 to the wastegates, 1 to the solenoid. Now if the solenoid failed.. my guess would be it would stay closed which would give you stock boost.

okay, is there any one way valves? on it maybe? basically it cops a feed of vaccuum wether you have the solenoid on or not, maybe it is the restrictor in the line causing it enough restriction to only produce stock boost when the solenoid is disconencted?

Edited by oRiCLe
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my_gtr32 Collaborator

my_gtr32

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Hi, interesting post great information. I have a few questions I would like answers though.

My gtr had the restrictor olives removed before I purchased the car. I was given the two olives in a bag. I know one goes in the hose with the yellow stripe near the boost control solenoide, where does the other go?

Why have people said you can't fit the olives back in and to purchase another hose? I'm sure it will be tight but if you're careful and use say, a dril bit or something to make sure the hole in the olive is clear and does not go in sideways and block the pipe, should be ok. I haven't tried it yet, just a thought.

I'm thinking of reducing the boost as I noticed there was some boost creap on a recent dyno run. With the information I've read in these posts, I will be checking the condition of the wastegate actuator control lines for leaks etc. Maybe one of the actuators or wastegates is being restricted and therefore the turbos are making more boost than 1 bar. I'm running standard ceramic turbos!

Thanks guys

Hmm this is possible.. with the stock restrictor in there and the solenoid removed it may not bleed enough out to cause unlimited boost.. it would be more than just having a pure pressure feed though.

Thats a thought.

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my_gtr32 Collaborator

my_gtr32

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Anyone?

A garage in Melbourne told me you must fit both restrictors in to drop the boost. It's news to me, I thought there was only one olive. But I have two in the bag so it must go somewhere?

I wonder how may people have only removed / installed one?

I have refitted the restrictor before.. no problem. Not sure what they mean.

I don't know where the second one is fitted sorry.

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Merli Grand Master

Merli

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I can't admit to studying the stock solenoid system too much (it's one of the first things to get the bin :()

But I think that some people in this thread are mistaking the 3-port setup of most aftermarket EBCs and the 2-port setup of the stock solenoids :(

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