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Thread: TURBO info required

  1. #1
    tank140 is offline Landrover defender 140 GMC 6.5 V8 turbo diesel
    Join Date
    Jul 2009
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    Warrington ENGLAND
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    Default TURBO info required

    Hi all

    Does anyone know what is the differance between the GM turbos?

    i.e. GM3 GM5 GM6 GM7 GM8

    what is the main differance of the turbo?

    as i have a GM8 on my 6.5 V8


    anyone know?


    cheers
    tank


  2. #2
    Join Date
    Apr 2001
    Location
    Newberg Oregon
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    12,282

    Default

    Mostly its in the bracketry and such and how the wastegate actuator is mounted.

    The basics of the turbo are about the same I am led to believe.

    The compressors specs are the same inside.

    Also I can't say from actually taking them apart and comparing but this is what I have been told.

    The only real differences as I mentioned are slight running changes to suit other changes in the build such as air filter type and location.

    The early turbo trucks did not have the top brace bar that ran from the engine to the turbo oulet casting.
    This was added later to either stop cracked manifolds or as an after thought to prevent it.

    The early turbos (92-93) had a spring device on the wastegate that worked just like a turbo master other than it was set at a fixed boost level.

    The GM 4 was used in 94-95 and these were basically the same except they had the vacuum controlled wastegate actuator that ran off the computer control.

    96 saw some changes in the air filter design on some models and the wastegate actuator was relocated to work with these changes.

    Again the overall design is very very similar all across the lineup.

    Some of the guys here that have worked with the turbos a lot may know of any real internal differences but I dont think there was much change.

    One of the biggest issues with the GM-X series is the exhaust outlet housing. The flow through these is not the best and under high boost levels the backpressure starts to climb and they tend to hold a lot of excess heat in the heads.

    If you have the room to work with, there are far better turbos out there that will really flow some air through these engines.

    A better flowing turbo will really help lower Exhaust gas temps.

    As far as what GM-X to use, its a mix and match game pretty much.

    Use what you find and modify to suit the application.

    Beat to fit, pound to suit and paint to match

    Just a little humor

    Missy
    (1) 1995 Suburban 2500 4x4
    (1) 1997 Astro
    (1) 2005 Suburban (Papa Smurf)
    THIS IS BOW TIE COUNTRY

  3. #3
    tank140 is offline Landrover defender 140 GMC 6.5 V8 turbo diesel
    Join Date
    Jul 2009
    Location
    Warrington ENGLAND
    Posts
    29

    Default Glow plugs

    Hi Robyn

    Many thanks for the info on extracting the GLOW plugs with expanded ends.
    It was still a bitch of a job with the injector out as the end of the glow plug was to long for the chamber i had to use a 8 mm allan key to bend the sucker to fit in the chamber, but i got the suckers out took me about 2 hours to get the two out.

    at one stage i thaught i needed to take the dam head off but abit of poking about sorted it

    many thanks

    tank
    Landrover 142 defender GMC 6.5 turbo diesel
    rear mounted turbo
    Loads of GM engine parts all over my garage

  4. #4
    Join Date
    Apr 2001
    Location
    Newberg Oregon
    Posts
    12,282

    Default

    Didn't say it was easy just that it was possible.

    So glad you got it done OK

    OH BTW, Lovely Pix of your rig.

    Best

    Robyn
    (1) 1995 Suburban 2500 4x4
    (1) 1997 Astro
    (1) 2005 Suburban (Papa Smurf)
    THIS IS BOW TIE COUNTRY

  5. #5
    Join Date
    Sep 2001
    Location
    Lubbock TX, USA
    Posts
    4,194

    Default

    FYI GM6 & 7 are center mount turbo's H1 & Savanna Van engines.

    J

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