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Thread: By-passing rear BSC and Vac Box

  
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    DJ Sheridan's Avatar
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    By-passing rear BSC and Vac Box

    Hi all,

    Well I got around to doing this little modification to my Zafira GSi Turbo and all...

    I used 3mm ID Samco yellow hosing (Yes... yellow!!! ) but as the nipple on the OE DV on the turbo seemed to be about 5mm I utilised the thicker hosing already on it AND cut a 2" piece from the original tubing from around the Airbox...

    Then I pulled out the pipe going to the TB but the thicker hose and harder piping bit on it stayed put so just pushed on my yellow hosing onto this.

    After T-ing in for FPR I tidied everything up... and switched on.

    Now not sure what it drives like (that's for later ) but it did sound a little bit noisier on the DV which sounded good... Glad I did not hear any chattering...

    What exactly would really bad turbo chatter sound like on an origianl set up with this mod?

    Dave
    If she's not sticking her fingernails into the roof lining and digging her stilettos into the dash then you ain't going fast enough!!!

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    rhys57's Avatar
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    I get some chatter sort of squeeling sometimes under full throttle sometimes doesnt sound good.
    Vxr turbo with 360 bearing and twin oils seals & Evoms dv. Cdti airbox 63mm tophat.Milltex cat back and pre cat.. Regal 245 leh phase 1 ipf remap.Whiteline rarb.

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    DJ Sheridan's Avatar
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    Quote Originally Posted by rhys57 View Post
    I get some chatter sort of squeeling sometimes under full throttle sometimes doesnt sound good.
    Have you had your actuator reset?

    I was thinking of adjusting it but not sure how to...

    The chatter I'm getting does not sound God-awful but just standard so i'm hoping no problems...

    ...now must take it out tonite

    Dave
    If she's not sticking her fingernails into the roof lining and digging her stilettos into the dash then you ain't going fast enough!!!

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    Pete 2's Avatar
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    Let us know how it drives like & what you think mate of it please mate.

    I did read that it is much smoother etc, but also read that by by-passing the rear bcs & vac box you lose the over-boost protection.
    Is this right?

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    Quote Originally Posted by Pete 2 View Post
    Let us know how it drives like & what you think mate of it please mate.

    I did read that it is much smoother etc, but also read that by by-passing the rear bcs & vac box you lose the over-boost protection.
    Is this right?
    I have done the bypass and it overboosts to 0.8bar and drops to 0.5/0.6bar and holds. I thought the rear bcs was to bleed off boost in 1st and 2nd gear so it doesn't come on full boost so its not as agressive? Isn't the front bcs a form of protection for boosting problems?
    SILVER ASTRA GSI RUNNING . . . . . . . HA HA THAT WOULD BE TELLING

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    Sorry to highjack your thread but i'm looking to do this (at the same time as I change my knackered AFM)...

    my question is, what do you do to the actual rear BCS plug? just unplug the pipes and leave it? do you need to block it up?

    cheers
    GSi Turbo - CS2 - 253bhp / 275ft/lb Torque
    1/4 mile - 14.62secs @ 95.5mph

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    Leave it plugged in and just disconnect the vac pipe from it then block it off with a price of pipe with a screw in it

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    I just unplugged all the pipes from the bcs and vac box and took them out of the engine bay, then connected a hose from the throttle to the oe valve on turbo then t'd in everything on that pipe eg. am dump valve, boost gauge etc
    SILVER ASTRA GSI RUNNING . . . . . . . HA HA THAT WOULD BE TELLING

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    qwalitee mate! sounds really simple... probably because it is and im worrying about nothin
    GSi Turbo - CS2 - 253bhp / 275ft/lb Torque
    1/4 mile - 14.62secs @ 95.5mph

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    Quote Originally Posted by GSI_Butch View Post
    qwalitee mate! sounds really simple... probably because it is and im worrying about nothin
    Yeah just do what I did m8 and use a t peice that acted like a one way valve lol, was trying to figure out for hours why my am dump valve wasn't working
    SILVER ASTRA GSI RUNNING . . . . . . . HA HA THAT WOULD BE TELLING

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