The Galant Center - Powered by vBulletin

Thread: Wastegate Springs

Showing results 1 to 8 of 8
  1. #1

    Wastegate Springs

    I bought a 38mm Tial wastegate for my turbo build and my goal for starting boost is 5-7psi.
    Now I google searched and am getting mixed results about using the external wastegate and what spring I should be using.

    So looking at the Tial spring chart, my goal should be the small red spring ~5psi








    I'm using a Hallman pro Manual Boost Controller to manage my boost.

    So this is where my confusion is:
    Spring says it will open at 5psi, but I'm reading if I were to use a MBC then I can run higher boost with a lower boost spring?




    Doesn't make sense to me.


    Lancer/EvolutionX Rotor Glow Paint
    6g74 Forged Engine w/ hx40 turbo
    Eclipse GT 5 spd swapped


    Rotor Glow Galant
    Daily Galant
    OZ Edition Eclipse

  2. #2
    Yeah that's right.
    Basically, the mbc is allowing you to build more boost by adjusting a spring tension rate and ball. So inside the mbc you can see 15psi, but the waste gate side only sees 5psi. Hopefully that helps

    AWD Converted Forward Facing 6466 E85 EVO 8 ECU Powered 2003 Galant

  3. #3
    You are here entirely tooo much!! Galanttuner10's Avatar
    Join Date
    08-13-2008
    Location
    Waterbury, CT
    Posts
    3,331
    Exactly what he said, the boost controller basically lowers the pressure the wastegate sees so say you turn the boost controller to 10 psi, the wastegate thinks its seeing 5 still. My spring is the large green 13 psi. External wastegates are the best way to go as long as they vent from the atmosphere to keep the exhaust flow much smoother.
    2014 Lancer Evo GSR
    1996 Galant S 5 Speed Turbo
    Need a Turbo rebuilt or upgraded--> http://www.thegalantcenter.org/showt...ebuild-Service

  4. #4
    ahh okay.. So in order for the wastegate to open, it must see 5psi at the "boost line" instead of 5psi in the exhaust manifold.

    I was thinking 5psi intake pressure = 5psi exhaust pressure. Which would open the external gate.
    This is wrong then ^^^


    Lancer/EvolutionX Rotor Glow Paint
    6g74 Forged Engine w/ hx40 turbo
    Eclipse GT 5 spd swapped


    Rotor Glow Galant
    Daily Galant
    OZ Edition Eclipse

  5. #5
    You are here entirely tooo much!! Galanttuner10's Avatar
    Join Date
    08-13-2008
    Location
    Waterbury, CT
    Posts
    3,331
    My BOV and wastegate use the same port on the intake manifold which was for the EGR valve prior. Everything needs to run off intake pressure
    2014 Lancer Evo GSR
    1996 Galant S 5 Speed Turbo
    Need a Turbo rebuilt or upgraded--> http://www.thegalantcenter.org/showt...ebuild-Service

  6. #6
    TGC Lifetime Patron finald8ta's Avatar
    Join Date
    02-17-2011
    Location
    i live in sunny florida
    Posts
    1,240
    im still learning turbos and what not, still reading up,
    im working with a 16g with internal wastegate

    so what your saying is a MBC wont let the wastegate up at all since the MBC is stopping it from seeing say 10psi and the MBC is now set to 15psi.. and the MBC is inline with the wastegate

    im just abit lost here, any help would be great

  7. #7
    Everything is run off intake manifold pressure. When you go into throttle and build boost it builds manifold pressure. The MBC is put in a line coming off the manifold that sees this pressure and is set to whatever you'd like to run for boost, say 10 PSI. Only once the manifold pressure goes over 10 psi does it go through the boost controller and down to your wastegate. The wastegate has a port BENEATH the diaphragm. The pressure then works against the wastegate spring. If you have a 5 psi spring, it needs 5 psi boost pressure at the wastegate to open it. This is why an MBC allows you raise boost above the wastegate spring pressure; it only lets pressure through once it hits your desired boost and if it's anything above wastegate spring pressure it will open.


    The blow off valve is basically the opposite. It has a vac line attached to the intake manifold that runs ABOVE the diaphragm in the valve. This way when you go into boost that pressure pushes down WITH the spring and keeps the valve shut. Then, when you shift and the manifold goes into a huge vacuum spike the vacuum pulls up on the diaphragm and opens so the boost in the intake can effectively "blow off" and either recirculate of vent to atmosphere.



    Keith you're best grabbing a 5 psi spring for your gate. Then add boost with the MBC as you move up.
    Last edited by Silvertune; 08-09-2012 at 07:11 PM

  8. #8
    Thanks a ton for the explanation guys! Very helpful!


    Lancer/EvolutionX Rotor Glow Paint
    6g74 Forged Engine w/ hx40 turbo
    Eclipse GT 5 spd swapped


    Rotor Glow Galant
    Daily Galant
    OZ Edition Eclipse

Posting Rules

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •