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egt probe after turbo?

Posted by dsmcurse, Sep 21, 2009

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  1. dsmcurse

    dsmcurse Proven Member

    884
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    Joined Aug 14, 2009
    Pasco, Washington
    when i used a stock style evo 3 exh. manni. i had the egt probe tapped into the manni. real close to the engine on the number one runner. now that i have new turbo set up, and im so close to gettin my car runnin agin i was wondering if the difference in temp will be that great compared to my old set up? my hx40 is t4 flange not mitsu so i got a nice stainless turbo header. i cant really see my self drilling and tapping this header as it will be very hot and have to hold up the weight of the very heavy hx40. so my probe will go in by the O2 sensor after the turbo. is this inaccurate?
     

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    1995 Mitsubishi Eclipse GSX
    manual · 2G DSM
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  2. silvreclips

    silvreclips Proven Member

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    Greenville, South Carolina
    Yes this is fine, actually many people prefer to mount it in this location because if it melts its not going to mess up your turbine wheel. You will read about 200F lower than right out of head tho.
     

    Autocross Build 161  1

    1998 Mitsubishi Eclipse N/T
    fwd · manual · 2G DSM
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  3. Rob10_99

    Rob10_99 Proven Member

    1,659
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    Joined May 22, 2005
    Ptown, Arizona
    The difference from inches after the valve VS post turbine are huge, as stated 200F or more.
    I would keep the EGT probe as close to the valve as possible, that's why it's there right? To see the temp of your cylinders/pistons?
     

    1K  0

    1998 Eagle Talon TSi AWD
    29.320 @ 55.000 · 2G DSM
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  4. 1gDSM4g63

    1gDSM4g63 Proven Member

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    Joined Aug 28, 2007
    San Jose, California
    You should tapped it in the first runner of the manifold.
     

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    1990 Eagle Talon TSi AWD
    manual · 1G DSM
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  5. Boostjunki84

    Boostjunki84 Proven Member

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    Joined Oct 12, 2007
    Candler, North Carolina
    +1 for tapping the manifold. If you are going to have it, it might as well be accurate. Without doing this you would be essentially guessing anyway.
     

    309  0

    1996 Eagle Talon TSi
    manual · 2G DSM
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  6. notverygood

    notverygood Proven Member

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    Joined Sep 7, 2009
    big bad bithlo, Florida
    I Installed my probe after the turbo and it read over 300 degrees cooler than the same probe PRE-TURBO. Seemed like it gave me a false sense of security-as aluminum melts around 1200, I wanted to make sure to be as close to the combustion chambers as possible. good luck.
     
  7. dsmcurse

    dsmcurse Proven Member

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    Pasco, Washington
    i havent seen any one tab a runner of turbo header. if anything id have to have it done where all 4 runners meet and its a collector right before the flange where the turbo bolts onto. if i drill and tap here how will it affect the integrity of the stainless header? i have seen egt's in the collector part. but have also heard horror storys of this leading to major cracking. im kinda indecisive on what i should do. any more suggestions?
     

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    1995 Mitsubishi Eclipse GSX
    manual · 2G DSM
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  8. vanilla gorilla

    vanilla gorilla Proven Member

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    Joined Sep 11, 2007
    Orrum, North Carolina
    On my 4g64T, I used to run a pyrometer. I had my EGT probe in the first runner (farthest from the fuel pump) of my mild steel tubular header. It was right off the head, like an inch and a half from the flange. I ran it like this for a while with no problems whatsover. And no, LOL, the probe didnt melt or break or anything....why would it? Its made to be in a hot environment. Under WOT I would see temps of around 1550, and the prettiest tipped spark plugs ever (this was all before I got a wideband). Not sure if they would be any difference in temp readings for a 4G63T.
     
  9. d_hidayat2000

    d_hidayat2000 Probationary Member

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    Sydney, Australia
    4G63T EGT should be around 800 deg C till 825 deg C on WOT
     
  10. knochgoon24

    knochgoon24 DSM Wiseman

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    Troy, Michigan
    Because of the laws of thermodynamics, you WILL see a lower temperature after the turbo than you would in the the runners.

    The turbo just doesn't extract energy from the pressure of exhaust gases. There is also a temperature drop between the turbine inlet and outlet.

    As long as you take that temperature drop into account, you should be fine.
     

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    1997 Mitsubishi Eclipse Spyder GST
    fwd · manual · 2G DSM

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    1991 Eagle Talon N/T
    manual · 1G DSM

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    1996 Mitsubishi Eclipse GST
    automatic · 2G DSM

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    1997 Eagle Talon TSi AWD
    13.869 @ 95.090 · 2G DSM
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  11. dsm-onster

    dsm-onster DSM Wiseman

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    Bloxom, Virginia
    Why do you want to use a pyro? You're better off with EvoScan and a wideband. . . You can actually log a knock sum with EvoScan :)
     

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    1990 Mitsubishi Eclipse GST
    manual · 1G DSM
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  12. d_hidayat2000

    d_hidayat2000 Probationary Member

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    Joined Sep 18, 2009
    Sydney, Australia
    Yup evoscan and a wideband should be good enough, if you don't run extreme AFR, just run the safe AFR like 12,5 during spool up and 10,9 under full boost
    BUT
    if you want to use the race gas and lean out the AFR, You'll need this EGT
    the leaner the AFR (till around 12,5) = More Power = More Heat

    and I'll put his EGT before the Turbo, because You can't calculate the exact temperature drop before and after the turbo on various load condition
    I think Nobody want to read false EGT
     
  13. Defiant

    Defiant DSM Wiseman

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    glorious Galt, California
    Pointless. Well, even more pointless than an EGT gauge, which on a street car is just another "Too Late" gauge.
    Your turbo runs on heat, not pressure. It converts that heat to kinetic energy and depletes it as it spins up.

    Damaging exhaust temperatures occur so quickly in a mis-tuned engine that trying to prevent them by use of a laggy gauge is like trying to steer by looking out the back window and guessing where the road went just before you crashed.
     

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    1995 Eagle Talon TSi AWD
    manual · 2G DSM
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