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  1. #1
    connorrxp's Avatar
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    AFR sensor placement for TURBO

    I want to turbo my ski or my brothers ski.. maybe both. Does the afr sensor have to be in the downpipes after the turbo? Or can it be in the manifold like it was with the supercharger? I don't see why there would be a huge difference but maybe I'm missing something.


  2. #2
    GRF + DashPac:) seadoo02xp's Avatar
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    After the turbo in the down pipe. If you put it in front it will read richer than actual afr due to pressure on the Inlet side of the turbo


    Sent from my iPhone using GreenHulk PWC Performance Forums

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    rxpredviper's Avatar
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    Quote Originally Posted by seadoo02xp View Post
    After the turbo in the down pipe. If you put it in front it will read richer than actual afr due to pressure on the Inlet side of the turbo


    Sent from my iPhone using GreenHulk PWC Performance Forums
    i have my in exhust now read 11.7 wot , so you saying that I'm running lean or Rich?

  4. #4
    Site Admin Green Hulk's Avatar
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    Quote Originally Posted by rxpredviper View Post
    Quote Originally Posted by seadoo02xp View Post
    After the turbo in the down pipe. If you put it in front it will read richer than actual afr due to pressure on the Inlet side of the turbo


    Sent from my iPhone using GreenHulk PWC Performance Forums
    i have my in exhust now read 11.7 wot , so you saying that I'm running lean or Rich?


    If you have your 02 sensor before the turbo its reading richer than actual by about a point. So if you are reading 11.7 now it's actually around 12.7 (lean)

  5. #5
    connorrxp's Avatar
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    well crap.....

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    Seems like I watched a motec vid about lambda sensor placement and the father away from the exhaust source you are basically looking at the reading from the past. Basically the event already happened. There is some math you can do to figure it out and adjust the correlation Between the time the reading is taken and the actual RPM. I'm trying to find the video again.

    For cars with turbos I think heat becomes a factor on placemeant, but since the sensor is in a water jacketed aluminum housing on our skis I am thinking it should be ok...guess time will tell. I kept loosing sensors in the down pipe so I moved back to the stock location. I also monitor egt as well. I've never heard anything about pressure on the sensor being an issue, have to look into that. I'll through another sensor on in the down pipe and see what happens.

    If you are at a steady state, say wide open throttle; I would think the readings would be the same or very close as the air/fuel ratio shouldn't change based on distance from the engine unless more air or more fuel is introduced.

  7. #7
    dlamazing's Avatar
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    Quote Originally Posted by DinoMite View Post
    Seems like I watched a motec vid about lambda sensor placement and the father away from the exhaust source you are basically looking at the reading from the past. Basically the event already happened. There is some math you can do to figure it out and adjust the correlation Between the time the reading is taken and the actual RPM. I'm trying to find the video again.

    For cars with turbos I think heat becomes a factor on placemeant, but since the sensor is in a water jacketed aluminum housing on our skis I am thinking it should be ok...guess time will tell. I kept loosing sensors in the down pipe so I moved back to the stock location. I also monitor egt as well. I've never heard anything about pressure on the sensor being an issue, have to look into that. I'll through another sensor on in the down pipe and see what happens.

    If you are at a steady state, say wide open throttle; I would think the readings would be the same or very close as the air/fuel ratio shouldn't change based on distance from the engine unless more air or more fuel is introduced.
    I've had mine on the manifold for years already and it runs 12.0 so I would be runnning a 13.0 to some ppl I think it would have melted by now

  8. #8
    JFizzleJR's Avatar
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    Quote Originally Posted by dlamazing View Post
    I've had mine on the manifold for years already and it runs 12.0 so I would be runnning a 13.0 to some ppl I think it would have melted by now
    How many degrees timing at full throttle?

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    connorrxp's Avatar
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    I'm confused as to how the sensor would screw up if the motor is getting 16psi from a rude supercharger or 16psi from a turbo the exhaust should have the same amount of gases in it.. if measuring further away from the exit is a thing, would throwing one of those billet spacers in help any?

  10. #10
    dlamazing's Avatar
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    Quote Originally Posted by JFizzleJR View Post
    Quote Originally Posted by dlamazing View Post
    I've had mine on the manifold for years already and it runs 12.0 so I would be runnning a 13.0 to some ppl I think it would have melted by now
    How many degrees timing at full throttle?
    I don't know exactly Brian tuned it is got a torx map in it

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