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Porting 2G O2 to Evo III 16G

Posted by High PSI, Nov 18, 2019

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  1. High PSI

    High PSI Proven Member

    119
    6
    Joined Oct 21, 2004
    USA, Australia
    I'm installing a JusMX billet bastard 20g in place of the old and trusty ported 14B that I've had on the car for the past ~16 years/20,000 miles. ROFL The housings is off a knockoff Chinese 16G that had everything thrown away except the compressor cover (which has been machined), turbine housing, and actuator. It has a completely-new CHRA and the upgraded thrust parts have been installed along with a KTS D620C billet 6-blade 20G compressor and a Kamak/Kinugawa 9-blade TD05H turbine.

    I have a 2g O2 sensor housing that I previously port-matched to the Mitsu turbo-to-O2 Housing gasket, and as such it exactly matches the new O2 gasket that I have. When I lay this gasket over the turbo, the hot-side-outlet is slightly larger than the gasket around the entire outer diameter, but particularly at the web between the wastegate and the hot-side-outlet.

    I thought that I possibly was using the wrong gasket (T25/14B as opposed to Evo3), but have since been informed that Mitsu uses the same gasket for all three?

    Of course, at the the wastegate section of the turbo there is a lot of material there that I ported out on the 2G O2 sensor (and my prior turbo) to match the gasket.

    I am considering port-matching the hot-side-outlet of the gasket to the turbo, then further port-matching my O2 sensor housing to this ported gasket (very little porting required here). On the wastegate opening, I am uncertain as to whether I should hog out the turbo to match the gasket and O2 housing, or leave it as is and just let the air-path open up at the O2 housing? I'm leaning towards leaving it as-is - not worried about creep with my current setup (2.3L, built head, supporting mods) and concerned that porting out the wastegate side would leave too thin of a web between the two outlet sides.
     
    ErikTande likes this.
  2. rabenne

    rabenne Proven Member

    991
    223
    Joined Apr 21, 2006
    Racine, Wisconsin
    Have you ever heard they saying "a picture is worth a thousand words"?

    I think a few pics here would be instrumental in getting help... I want to understand, but that's a lot of confusing description! (and my reading comprehension sucks)
     

    Street Build 219  5

    1996 Mitsubishi Eclipse GSX
    awd · automatic · 2G DSM

    Street Build 159  12

    1997 Mitsubishi Eclipse GST
    fwd · automatic · 2G DSM

    Street Build 7K  9

    1995 Eagle Talon TSi
    awd · manual · 2G DSM
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  3. ErikTande

    ErikTande Proven Member

    839
    228
    Joined Dec 17, 2012
    Centennial, Colorado
    Yeah, post a few pics of the turbo and housing : )
     

    Street Build 765  1

    1997 Eagle Talon TSi AWD
    awd · manual · 2G DSM

    3K  7

    1990 Mitsubishi Eclipse GSX
    13.2 @ 105 · 1G DSM
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  4. High PSI

    High PSI Proven Member

    119
    6
    Joined Oct 21, 2004
    USA, Australia
    Sorry...took all these before; forgot to attach!

    As noted the O2 housing gasket is smaller than the turbo hot-side outlet, so obviously can't see the difference with the gasket layed over the turbo. It's a very small difference (~1/16" lip around the entire outside, though as noted thicker at the flange).
     

    Attached Files:

  5. ec17pse

    ec17pse Freelancer

    3,446
    1,336
    Joined Nov 1, 2008
    London, Europe
    The evo 3 gasket is different then a dsm gasket, the dsm has a smaller turbine but huge wastegate hole but the evo is huge turbine but smaller wastegate hole.

    Either not worry about it and bore what you can.
     

    Road Race Build 8K  10  51

    1997 Mitsubishi Eclipse GST
    175 whp · 180.1 lb/ft · 2G DSM
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