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Using a 99 GST to build my 99 GSX

Posted by SwiftKidGSX, Sep 6, 2020

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  1. SwiftKidGSX

    SwiftKidGSX Proven Member

    96
    5
    Joined Jul 11, 2003
    Cerritos, California
    Its been 15 years this project been on hold and forgot everything as to what bolt goes where and part.

    It had a Japan 6bolt motor before so all that wiring is in place and I will be reverting back to a US 7bolt. I was then working towards a 2.4 build using the hyundai sonata block formula.

    I have a few questions before I pull the trigger in purchasing a lightly damaged 99GST and would like your thoughts and see if what I'm about to do is smart...The plan in purchasing the GST is to have a guide to know where everything goes.

    Is the gas tank and lines that run under the car a direct swap? It still has the old gas of 15 years.
    My HKS cams 264|272 have very light rust on the lobes, are they still functional? Or don't risk it.
    Are the 660 injectors still good or get new ones?
    Are both ECU's the same?
    No issues with the CAM angle sensor, right?

    I know I would be rolling the dice on the car's engine health here but this is just to the GSX rolling and have a heart beat again and slowly build it back up.

    Thanks for your input and advise fellas.

    Joey
     

    399  0

    1999 Mitsubishi Eclipse GSX
    12.230 @ 112.160 · 2G DSM
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  2. JPenny

    JPenny Proven Member

    174
    52
    Joined Feb 24, 2016
    Corpus Christi, Texas
    I'm pretty sure gas tank from gst is not the same as gsx
     

    222  6

    1996 Mitsubishi Eclipse GST
    manual · 2G DSM

    Street Build 2K  4

    1997 Mitsubishi Eclipse GST
    fwd · manual · 2G DSM
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  3. SwiftKidGSX

    SwiftKidGSX Proven Member

    96
    5
    Joined Jul 11, 2003
    Cerritos, California
    It was a coin toss, was hoping it would be.

    Thanks for the reply JPenny.
     

    399  0

    1999 Mitsubishi Eclipse GSX
    12.230 @ 112.160 · 2G DSM
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  4. spyderdrifter

    spyderdrifter Freelancer

    4,944
    552
    Joined Jul 11, 2009
    Fountain, Colorado
    JPenny is right, the tanks are quite different, but the physical lines are the same. Years ago when I converted my old spyder to AWD, I never swapped any lines out. Used the FWD lines with the AWD tank and everything mated perfectly. The ECUs are basically the same. You can interchange them without problem. The only difference is the GSX ECU is rated for a slightly higher top speed.
     

    2K  2

    1996 Eagle Talon TSi AWD
    awd · manual · 2G DSM

    2K  3

    1995 Mitsubishi Eclipse GSX
    awd · manual · 2G DSM

    2K  5

    1999 Mitsubishi Eclipse N/T
    automatic · 2G DSM
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  5. Jays99Spyder

    Jays99Spyder Proven Member

    123
    36
    Joined Feb 22, 2020
    Waukegan, Illinois
    I would buy the gst engine bay harness if you do. For a reasonable price that is. I'm still using my 99 gs spyder harness. Now that I think about it idk if there is a difference between the spyder gst and reg gst so I guess I'll have to research that first before pulling the trigger.
     

    Street Build 316  4

    1999 Mitsubishi Eclipse GS Spyder 4G63 Swap
    fwd · manual · 4G63t Swapped
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  6. spyderdrifter

    spyderdrifter Freelancer

    4,944
    552
    Joined Jul 11, 2009
    Fountain, Colorado
    There isn't a difference between those two harnesses, you are correct.
     

    2K  2

    1996 Eagle Talon TSi AWD
    awd · manual · 2G DSM

    2K  3

    1995 Mitsubishi Eclipse GSX
    awd · manual · 2G DSM

    2K  5

    1999 Mitsubishi Eclipse N/T
    automatic · 2G DSM
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  7. Jays99Spyder

    Jays99Spyder Proven Member

    123
    36
    Joined Feb 22, 2020
    Waukegan, Illinois
    Awesome thanks didn't know because one is convertible and the other isn't.
     

    Street Build 316  4

    1999 Mitsubishi Eclipse GS Spyder 4G63 Swap
    fwd · manual · 4G63t Swapped
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    spyderdrifter likes this.
  8. 2Gjunkie

    2Gjunkie Proven Member

    88
    33
    Joined Aug 5, 2020
    Baltimore, Maryland
    You can always get the injectors flow tested and cleaned if you want to make sure. $100 for cleaning is a lot better than $200-300 for new imho. I wouldn’t run them as-is, though. 15 years of sitting is a long time.
     

    Street Build 187  3

    1998 Mitsubishi Eclipse Spyder GST
    manual · 2G DSM
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  9. 97egl

    97egl Proven Member

    132
    17
    Joined Feb 6, 2014
    Brownsburg, Indiana
    Your going to need to clean or replace the tank. This is a tank I had that had 10 year old gas sitting in it. That brown stuff isn't rust it's a build up of varnish on the tank. I sprayed it off as best I could with a pressure washer. You have to use hot soapy water and let the tank sit in the sun and get as hot as possible before you do it so the water evaporates out when your done. You'll still get some flash rust but it's better than all the varnish
    1st Pic is before any pressure washing
    2nd pic is the same tube and bracket after a little bit of power washing. I spent about 2 hours total and had to cut 2 holes in the tank to get around all the baffles. Then weld and braze them shut for a leak free seal
    20200309_211602.jpg 20200313_191620.jpg IMO.
     

    162  3

    2002 Pontiac Grand Prix GTP 40th Anniversary
    fwd · automatic · Misc Vehicles

    Street Build 219  1

    1991 Plymouth Laser RS Turbo
    fwd · manual · 1G DSM
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  10. miguelmcv

    miguelmcv Supporting Member

    2,678
    201
    Joined May 3, 2009
    Fresno, California
    The fuel tank won’t be that bad but a clean would be nice to put some fresh fuel.

    The gsx fuel tank is rubber which it builds no rust, on the other hand, the gst fuel tank is metal, that will build rust like hell.

    Post some pics of the cams to see how deep is the rust, if it’s very light, a light polish would get the rust off.
     

    Street Build 847  1

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

    3K  0

    1995 Mitsubishi Eclipse GST
    manual · 2G DSM
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  11. SwiftKidGSX

    SwiftKidGSX Proven Member

    96
    5
    Joined Jul 11, 2003
    Cerritos, California
    20200911_165228.jpg
    Thanks for the reply's fellas! I found another GST with a 6bolt! Its been sitting for a while.

    I will post pictures of the cams when I start pulling and organizing everything out.

    I got to say I feel like a kid in a candy store if you know what I mean!
     

    399  0

    1999 Mitsubishi Eclipse GSX
    12.230 @ 112.160 · 2G DSM
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    Craig1970 likes this.
  12. SwiftKidGSX

    SwiftKidGSX Proven Member

    96
    5
    Joined Jul 11, 2003
    Cerritos, California
    20200912_152323.jpg 20200912_152323.jpg 20200912_152331.jpg

    Hi Fellas - Here are the pictures of the cams, the rust is raised away from the lobe, thought rust eats steel, its raised here..

    Thanks in advance!
     

    Attached Files:

    399  0

    1999 Mitsubishi Eclipse GSX
    12.230 @ 112.160 · 2G DSM
    Loading...
  13. SwiftKidGSX

    SwiftKidGSX Proven Member

    96
    5
    Joined Jul 11, 2003
    Cerritos, California
    Finally pulled the engine out and will be be getting it on the stand to build it back up. Swapping out the oil filer housing with an old one since that one is water cooled.

    20200916_144609.jpg
    Took the turbo to get rebuild at PT Turbos (Performance Techniques) and was shown the exhaust housing was cracked. Glad I took it since I didn't even notice it.

    Took the injectors to RC Engineering to get button up, they are getting machined with new internal seals.

    20200916_164125.jpg

    I also pulled out the fuel pump to also take to RC Engineering but it was in no condition to even bother, going to replace it. 15 years has taken its toll inside the gas tank. The fuel tank gasket [Part# 05261] and the bottom rubber part of the fuel pump turned into sticky GUM. The gasket cost me $36.25 at the dealer.

    My plan in the future is to run e85, what fuel pump should purchase to get that checked off? For now it will be 91 octane on 660 injectors, 20G.

    Thanks!
     

    399  0

    1999 Mitsubishi Eclipse GSX
    12.230 @ 112.160 · 2G DSM
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