Adjusting the wastegate arm
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This is a discussion on Adjusting the wastegate arm within the Engine Modifications forums, part of the Tech & Modifying & General Repairs category; Not much is ever mentioned about this mod and I wanted to know who here has done it and what ...

  1. #1
    Registered User mourning_air's Avatar
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    Question Adjusting the wastegate arm

    Not much is ever mentioned about this mod and I wanted to know who here has done it and what the result was. The best thread about this mod is over at nasioc: here and it has briefly been mentioned on this forum here and here

    In theory this mod stops/reduces/moves the wastegate opening that occurs at low boost (around 1-3psi) with aftermarket exhausts.

    A theory of why this happens is explained best by cuda:
    Originally posted by Cuda
    I'm pretty sure what's happening is that the wastegate is set to a specified setting, when you change the exhaust, mainly the uppipe and downpipe, you change the backpressure in the system causing the wastegate to not open correctly. Adjusting it tightens it up causing the wastegate to stay shut. Also, seems that bellmouths have the most problem with it. I've helped a few local people with this and every car is different and takes a different amount of turn in. Glad to hear it worked. I know just how annoying it can be!! It will also give you abit better boost response.
    Thoughts?
    <Ryan>
    '00 Silverthorn Metallic 2.5 RS
    '04 San Remo Red WRX Wagon

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  3. #2
    Registered User mourning_air's Avatar
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    here is an image for reference
    Attached Thumbnails Attached Thumbnails untitled.jpg  
    <Ryan>
    '00 Silverthorn Metallic 2.5 RS
    '04 San Remo Red WRX Wagon

  4. #3
    Registered User PoorAssRacing's Avatar
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    Nice presentation.

    I inquired about this a couple of weeks ago. If enough info if provided, I'd gladly help ya in return for the same on my car.
    Secretary of Silly Sports and Champion of WRB, Grand Republic of the Zem Dictatorship, 7/6/04

    I would lick parts of you for a chai. - Zem in an email
    The beauty of religious mania is that it has the power to explain everything. Once God (or Satan) is accepted as the first cause of everything which happens in the mortal world, nothing is left to chance... logic can be happily tossed out the window. - Stephen King
    Usually the team that scores the most points is going to win - John Madden

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    Registered User mourning_air's Avatar
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    Where is the thread where you asked about this... I couldn't find much info on it at all
    <Ryan>
    '00 Silverthorn Metallic 2.5 RS
    '04 San Remo Red WRX Wagon

  6. #5
    Registered User Rancid's Avatar
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    It looks pretty easy. I like posting more than I like dynamics take-home final. So in order to make this a useful post, I'm going to say something somewhat technical. Tighten it 5 turns and see what happens.
    www.awdpirates.net

  7. #6
    Registered User PoorAssRacing's Avatar
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    Originally posted by mourning_air
    Where is the thread where you asked about this... I couldn't find much info on it at all
    You hit the nail on the head....no one posted.
    Secretary of Silly Sports and Champion of WRB, Grand Republic of the Zem Dictatorship, 7/6/04

    I would lick parts of you for a chai. - Zem in an email
    The beauty of religious mania is that it has the power to explain everything. Once God (or Satan) is accepted as the first cause of everything which happens in the mortal world, nothing is left to chance... logic can be happily tossed out the window. - Stephen King
    Usually the team that scores the most points is going to win - John Madden

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    Registered User crazycam31's Avatar
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    Yup.... For technical stuff it seems I get better and more responses in MS.... But in anycase, I don't seem to get this problem, but I'm sure if it occurs (and bothers you) this seems to be logical. You could always try it and if the problem doesn't go away.... Then turn the other way. And then put it back.....

  9. #8
    Registered User mourning_air's Avatar
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    Update

    This does work and can be done in a few minutes.

    At one and a half turns shorter the wastegate noise was completelty gone, but I was getting a little more boost spiking than I wanted.

    I backed it down to one turn shorter and the wastegate noise comes on at a higher RPM range and is not as noticable. There is still a little boost spiking with one turn.
    <Ryan>
    '00 Silverthorn Metallic 2.5 RS
    '04 San Remo Red WRX Wagon

  10. #9
    tr3
    tr3 is offline
    Registered User tr3's Avatar
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    I tighten mine 2 turns and it's been great. It spikes a little bit but never goes higher than 15.5 psi. I have Cobb stg 2 by the way. Even with the Cobb reflash prior to adjusting the wastegate arm, I never got higher than 14.5 psi in any gear. But after the wastegate adjustment, I found the missing psi. Boost builds so much quicker and same smoothness as the reflash. If your car is boosting a little low, then you should give this a try. I'm loving it!

  11. #10
    Registered User Chris G's Avatar
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    Call me a n00b, but is boost spike bad for the car?

    I'm assuming as long as you're not spiking over like 17-18 psi on a stock turbo you should be okay? Is that correct?

    I need to get rid of the flutter as well, so I am curious

  12. #11
    Registered User mourning_air's Avatar
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    Here are my findings. I am stage II access port at 5380 ft

    Stock restrictors and wastegate setting - 14.5psi
    3/16th mod - 16.68 psi (spike)
    Wastegate arm adjusted one full turn, stock restrictor - 15.95psi (small spike) <--- current setting

    Once the boost settles down I pull at about 13.78psi tapering off at higher RPMs

    all readings taken from stock boost gauge

    I think I may try to shorten it another half a turn and see if the ECU can learn to control the spike a little better...
    Last edited by mourning_air; 05-04-2004 at 03:31 PM.
    <Ryan>
    '00 Silverthorn Metallic 2.5 RS
    '04 San Remo Red WRX Wagon

  13. #12
    Registered User mourning_air's Avatar
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    Does the STi turbo (vf39?) have an adjustable wastegate arm?

    edit: I thought you had an STi because of the fog covers...
    Last edited by mourning_air; 05-04-2004 at 03:38 PM.
    <Ryan>
    '00 Silverthorn Metallic 2.5 RS
    '04 San Remo Red WRX Wagon

  14. #13
    Registered User Chris G's Avatar
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    Nope, not an STI, need to update the avatar since I took off the stickers (on the fog covers)...

    Anywho, let me know what you find, I am really interested in doing this...

  15. #14
    Registered User Dream's Avatar
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    I think I need to do this also, im only getting like 12psi and im catless. Keep the info coming
    -2006 WRX Wagon-

  16. #15
    Registered User blackboost's Avatar
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    make sure you put that retainer ring back on, I lost mine, drove around for a minute, and lost all my boost cause the arm disconnected. Had to go to hardware store to buy another one.
    catless Cobb stage 2


    "That's only a v-4! My v-6 will beat you anyday" - dumbass

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