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Thread: Engine swap options for a first gen Impreza GX ?

  1. #1
    Member thetunersgroup's Avatar
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    Engine swap options for a first gen Impreza GX ?

    Hi all,

    A mate of mine has a very clean first generation (1993 - 2001) Impreza GX that he is looking at selling.

    Apparently it has the 1.8 litre normally aspirated engine with factory 4WD running gear.

    I am thinking of buying it from him as a project car and doing an engine swap on it.

    A couple of questions for the Subaru gurus ... I've never owned a Subaru before so apologies for the basicness of these questions ...

    How much torque will the factory gearbox, diffs and driveshafts in a 1993 - 2001 4WD Impreza GX handle ? ie to drop a WRX / STi motor into a GX would I just need to swap the motor or would it need to be a full drivetrain swap of engine / gearbox / diffs / driveshafts etc ?

    Does the 1993 - 2001 4WD Impreza GX have limited slip diff from factory ?

    Will a WRX / STi motor bolt straight up to the engine mounts and gearbox in a 1993 - 2001 4WD Impreza GX ?

    Is there a particular model of normally aspirated first generation normally aspirated 4WD Impreza that would be a better candidate for a WRX / STi engine swap ?

    We'd put bigger brakes, suspension etc into it of course - just checking first on drivetrain compatibility etc.

    Also will the WRX bonnet, bumpers etc bolt straight onto a GX ? And what options are there in terms of wider front and rear guards to squeeze more rubber under there ?

    Thanks,
    Adam
    Last edited by thetunersgroup; 13-08-10 at 10:16 PM.
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    Member zappy65's Avatar
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    The WRX engine will bolt straight in.

    My bro in law has a full WRX for sale (its been ritten off)
    EJ20T
    Tein Coilovers
    The whole whiteline catalogue
    reco'd gearbox and rear diff

    No panels untouched (it rolled on Mt Nebo)
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    tribeca engine with a gt42r
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    Member The Panda's Avatar
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    Quote Originally Posted by SUROK View Post
    tribeca engine with a gt42r
    CSB


    The standard GX running gear is unlikely to be able to handle the additional power, especially the diffs.
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    i thought gx and wrx pretty much the same arent they? in therms of drive train
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    Quote Originally Posted by thetunersgroup View Post
    How much torque will the factory gearbox, diffs and driveshafts in a 1993 - 2001 4WD Impreza GX handle ? ie to drop a WRX / STi motor into a GX would I just need to swap the motor or would it need to be a full drivetrain swap of engine / gearbox / diffs / driveshafts etc ?
    The factory drivetrain won't take abuse. It would be fine for a street driven occaisionally squirted car, but I wouldn't think it would last on the track.

    If I were you, I would drop in an EJ207 (STi motor, I'd go for Version 5 or above) and a newer STi 6 speed, differentials and upgrade the brakes. The STi drivetrains are very strong and will take a beating, so I recommend doing it once and doing it properly.
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    Quote Originally Posted by Bantex View Post
    The factory drivetrain won't take abuse. It would be fine for a street driven occaisionally squirted car, but I wouldn't think it would last on the track.

    If I were you, I would drop in an EJ207 (STi motor, I'd go for Version 5 or above) and a newer STi 6 speed, differentials and upgrade the brakes. The STi drivetrains are very strong and will take a beating, so I recommend doing it once and doing it properly.
    Great info there Bantex - thanks. I wasn't sure if the factory drivetrain on the GX used WRX parts etc.

    On some of the Porsche gearboxes it's possible to run a lot more power through them (the Supercharged 911 runs a 915 gearbox from a normally aspirated car for instance). I've heard some mechanics say that some 911 gearboxes will happily handle twice the rated horsepower.

    But I wasn't sure how much extra torque you can run through an Impreza gearbox, so thanks heaps for your info.

    Yes doing it once and doing it properly is definitely the way to go.

    - Adam
    Last edited by thetunersgroup; 15-08-10 at 10:36 PM.
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    Quote Originally Posted by zappy65 View Post
    The WRX engine will bolt straight in.

    My bro in law has a full WRX for sale (its been ritten off)
    EJ20T
    Tein Coilovers
    The whole whiteline catalogue
    reco'd gearbox and rear diff

    No panels untouched (it rolled on Mt Nebo)
    How much is he looking for for it ?

    Is he parting it out or selling the whole car ?
  9. #9
    Member Bantex's Avatar
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    Quote Originally Posted by thetunersgroup View Post
    Great info there Bantex - thanks. I wasn't sure if the factory drivetrain on the GX used WRX parts etc.

    On some of the Porsche gearboxes it's possible to run a lot more power through them (the Supercharged 911 runs a 915 gearbox from a normally aspirated car for instance). I've heard some mechanics say that some 911 gearboxes will happily handle twice the rated horsepower.

    But I wasn't sure how much extra torque you can run through an Impreza gearbox, so thanks heaps for your info.

    Yes doing it once and doing it properly is definitely the way to go.

    - Adam
    No worries Adam. Unfortunately Subaru 5-speeds aren't like Porsche or Supra gearboxes, and the differentials are not that strong either. The drivetrain from GDB STi's and above (so from bugeye shape STi onwards) are the first of the Subaru drivetrains that can take serious power.

    The 6-speed is regarded as being strong enough to handle 350kw at the wheels with no problems. Obviously, hard launches will decrease the lifespan of the box. The R180 differentials are of similar strength (also from 01+ STi)

    I'll try and answer your other questions, but I know more about second/third gen imprezas than I do about first gen so I may very well be wrong... If anyone sees mistakes with what I've written please correct me!

    Does the 1993 - 2001 4WD Impreza GX have limited slip diff from factory ?

    No, the front and rear diffs are open with a Viscous centre diff. The torque split (front/rear) is 50/50, whereas the DCCD STi drivetrain can be 35/65 to reduce understeer.

    Will a WRX / STi motor bolt straight up to the engine mounts and gearbox in a 1993 - 2001 4WD Impreza GX ?

    Not sure about the gearbox, and you may need new engine mounts to fit a newer engine. However I think it is a fairly straightforward conversion.

    Is there a particular model of normally aspirated first generation normally aspirated 4WD Impreza that would be a better candidate for a WRX / STi engine swap ?

    Not too sure, hopefully someone else with more knowledge than me can answer that one!

    Also will the WRX bonnet, bumpers etc bolt straight onto a GX ? And what options are there in terms of wider front and rear guards to squeeze more rubber under there ?

    I'm quite sure they bolt straight up. As far as wider guards, a 22B style widebody kit (like this one) is probably your best option to fit wider wheels, or alternatively you could just go bolt-on guards (some inspiration..):

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