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2G Stock boost line setup with external wastegate?

Posted by Kryndon, Sep 18, 2020

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  1. Kryndon

    Kryndon Proven Member

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    Joined Jan 10, 2014
    Bulgaria, Europe
    I'm felling embarrassed about asking such a newbie question, I should know better by now!

    However, it's my first time running an external wastegate and I'm trying to plumb it all to run with the stock electronic boost control solenoid and intake snorkel. I had a custom O2 housing made with a recirculated external gate, spring should be rated at 1.3 bar (19 psi). I want to retain the stock BCS because I will be further utilizing it once I have DSMlink. Also, I just don't trust cheap manual boost controllers.

    So, here is how I'm planning to run the lines, essentially the same as with the internal wastegate. Would this cause any problems? The gate I got has 4 total ports, two on each side (under and above the diaphragm). I only installed one nipple and used grub screws to cap off the other 3.

    In the following picture:
    1 - Compressor Housing nipple (boost source)
    2 - Top port of Wastegate
    3 - T-fitting
    4 - To intake snorkel (after MAF)

    119628130_821735701897203_155794629414435769_n.jpg
     

    Attached Files:

    Street Build 4K  12

    1997 Eagle Talon TSi AWD
    13.43 @ 99.7 · 2G DSM
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  2. Mello

    Mello Proven Member

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    Joined Jul 4, 2003
    Albuquerque, New Mexico
    I think you are using the wrong port on the EWG. You want to hook the boost line to the bottom port & leave the top vented. Also, I think you will have problems with a 19lb spring & the OEM ECU. ECU is programmed to work with a 7lb spring & will probably not do any controlling with the higher spring rate. Your minimal boost will be the spring rate & will not go lower. I would wait for ECM Link & just run the boost source directly from the compressor to the EWG & run spring pressure for the time being.
     
  3. Kryndon

    Kryndon Proven Member

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    Joined Jan 10, 2014
    Bulgaria, Europe
    Maybe I'm wrong, but my understanding is that if the boost source goes on top of the diaphragm, it will help push the wastegate closed and thus help build target boost (alongside the spring). If the boost source was under the diaphragm, it would fight against the spring and try to open it. Eventually, due to overboost, the turbo will simply force the gate open regardless.

    Also, with the stock internal wastegate the car ran fine with enough fuel up to ~22 psi, however due to the nature of the 16G, it crept way past that and eventually I hit fuel cut. 19 psi is safe for the current setup and stock map. But with this external gate I will finally be able to control the actual boost level without fear of boost creep.
     

    Street Build 4K  12

    1997 Eagle Talon TSi AWD
    13.43 @ 99.7 · 2G DSM
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  4. Mello

    Mello Proven Member

    1,178
    343
    Joined Jul 4, 2003
    Albuquerque, New Mexico
    I don't understand how you could get 22psi from the stock system. Were you running a manual boost controller?

    Pushing down with the top port would produce infinity boost.

    Get a different 3-port solenoid & hook it up like this
    445255d1319116335-electronic-boost-controller-comparison-chart-ewg_ebc-jpg.jpg
     
    Last edited: Sep 18, 2020
  5. Kryndon

    Kryndon Proven Member

    632
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    Joined Jan 10, 2014
    Bulgaria, Europe
    You're absolutely right. I had to look at my wastegate again and have a double take....... What I wrote above is nonsense. The boost source needs to always be opposite of the spring so that once desired boost level is made, the spring is squeezed and thus the valve opens, allowing the gasses to bypass and remain at target levels.

    In which case, I will move the nipple to the lower port, however I believe I should let the top port open to atmosphere so that it wont cause a vacuum above the diaphragm and potentially burst it. Later on I might run a 3 port EBC but for now I am sticking with the stock one.
     

    Street Build 4K  12

    1997 Eagle Talon TSi AWD
    13.43 @ 99.7 · 2G DSM
    Loading...
  6. Mello

    Mello Proven Member

    1,178
    343
    Joined Jul 4, 2003
    Albuquerque, New Mexico
     
    Kryndon likes this.
  7. jed344

    jed344 Supporting VIP

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    Joined Jan 10, 2008
    Waterville, Iowa
    I run boost source to bottom of gate and controller to top of the gate. That way it uses boost pressure to keep gate closed and also doesn’t allow the gate to slowly open slowing spool. With 18psi spring I see 30psi with only 40% duty.
     

    1K  38

    1997 Mitsubishi Eclipse GSX
    awd · manual · 2G DSM
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