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WBO2 Sensor Mounted in Center Section - Location? Clearance?

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  • WBO2 Sensor Mounted in Center Section - Location? Clearance?

    I'm planning to install a Bosch 7057 wide band oxygen sensor in my superspring center section.

    Any ideas as to where the best location for this would be? I'm guessing right in the x pipe, but am I better off putting a port into the leading side of the x-pipe or the trailing side?

    Also, any ideas what kind of clearance issue I may run into? According to the Bosch spec PDF I have for the sensor, I need to install it at at least 10degrees above the horizontal plane to prevent condensation between the sensor element and housing.


    Finally, does anyone have a picture of a superspring center installed in a car? I don't have an exhaust system in place right now, so I don't have anything to judge exactly where the x pipe sits in the underbody. I want to see what kind of room I have fore and aft to work with.

    Thanks,
    Chris

  • #2
    pic stolen from bubble car gallery:







    I know it's not a supersprint, but it's a couple of good shots from different angles.

    Dave

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    • #3
      No, that's actually pretty helpful. Thanks.


      Now, anyone care to comment on whether the sensor should be on the front of the xpipe or the rear, or maybe someplace completely different altogether.

      Comment


      • #4
        The closer it is to the engine, the faster the response time of the sensor, but you can run into overheating problems. Personally, I'd go for the x-over. There should be plenty of space above it to fit the sensor (might need to be at a slight angle left or right to clear the gearbox).
        Steve
        Scottish Cecotto

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        • #5
          Mines in the 'x-pipe' too.

          I chose it for two reasons. First I was afraid if I put it near the head, I wouldn't know if it went lean on the other two cylinders.

          Secondly it was easy to get a bung welded to the x-pipe as opposed to pulling the header off

          The best alternative is probably putting your wb02 in place of your oem narrow band one.

          1988 Silver E30 ///M3 - Sold
          1995 Yellow E46 ///M3 - Ex-GrandAm Cup Racecar
          1995 Silver E36 ///M3 - Crapwagon
          1995 Black E36 ///M3 - Crappier Crapwagon (Turbo)
          1995 Purple E36 ///M3 - Crappiest Crapwagon (Euro S50 powered)
          1969 BMW 2002/1602
          1986 BMW 325 turbo

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          • #6
            You must mount it as close to the original as possible.
            It needs to read the exhaust at the appropite temps or your readings, though present will be inaccurate and misleading.
            for example if it is putting out 0.84v.
            0.84v at 900*C is 11.8:1....a little rich
            0.84v at 750*C is 13.1:1....a little lean
            0.84v at 650*C is 14.1:1.... Bye-bye pistons.

            m

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            • #7
              Well, I've heard of problem with the sensor over heating. I can't remember the source, but I've been told the sensor should be at least 24" away from the exhaust ports on the head; the stock port doesn't meet this requirement.

              Also, since this sensor is more than capable of running at the tailpipe for a dyno setup, I don't see moving it back an extra foot (or 0.3048 meters to most of the world) would do anything but help. The sensor spec sheet says the operating temp is <= 930 C with a maximum of <=1030 C. It also mentions a decrease in accuracy above 850 C. There is no minimum operating temp given. All of this leads me to believe that "too hot" is much more of a possibility than "too cold". Anyone know what range e30 m3 EGT is? I haven't a clue.

              Also, I am planning to have the headers ceramically coated, so EGT will already be higher on the way out.


              Fritzintn: do have any pictures of where you located the sensor in the xpipe? On the "front" or the "back"? Did you have to angle it side to side at all for clearence?

              Thanks.

              Comment


              • #8
                Originally posted by Chris F.

                Also, since this sensor is more than capable of running at the tailpipe for a dyno setup, I don't see moving it back an extra foot (or 0.3048 meters to most of the world)
                Thanks. [/B]
                Who says this is the right thing to do..... Only by coping what others (might) do wrong doesn't make it right suddenly.

                Have a look at the stock location. The NB sensor is on a pice of pipe BETWEEN the downpipes, not in the "full" stream of gases.
                There is just a tiny 8mm hole to let exhaust gases to the sensor


                Goodbye M3, you served me well.

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                • #9
                  Originally posted by UweM3
                  Who says this is the right thing to do..... Only by coping what others (might) do wrong doesn't make it right suddenly.

                  Have a look at the stock location. The NB sensor is on a pice of pipe BETWEEN the downpipes, not in the "full" stream of gases.
                  There is just a tiny 8mm hole to let exhaust gases to the sensor
                  I don't really follow your comment/question. Are you questioning the ability to run the sensor from an exhaust tip mount? If so, I don't really have any info there. Lots of dyno tuners seem to using that method, but I can't say for sure if it is working right. I guess.


                  As far as the stock location, it seems to work for the narrow band thimble sensor. Does that mean it will work for the different WBO2 sensor? That's the question. The sensor design and operation is different.

                  TechEdge, who makes the WBO2 control unit but admittedly didn't design the sensor, recommends the unit be placed perpendicular to the exhaust gas flow. Clearly the stock location doesn't fit this.

                  Also, while the TechEdge unit does allow for the simulation of the NB signal, is there any reason I would be better off running two sensors instead?

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                  • #10
                    Whoever wrote that big thing about the WBO2 sensor group buy (I believe you posted it here, but it might have been written by Bob Conway from NJBMWCCA) said that the stock sensor location is fine. It may not be the best possible location, but it supposedly works fine. Keep let's keep this thread going because I want a definitive answer too!!
                    "It is needless to say that self-propelling vehicles, like other machines, will never do as much for one who does not understand them as for one who does."

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                    • #11
                      Originally posted by AlpineRunner
                      Whoever wrote that big thing about the WBO2 sensor group buy (I believe you posted it here, but it might have been written by Bob Conway from NJBMWCCA) said that the stock sensor location is fine. It may not be the best possible location, but it supposedly works fine. Keep let's keep this thread going because I want a definitive answer too!!
                      Actually, I was talking with Bob last night and that's what made me think of this topic. He felt the stock location might be too close for a "perfect" installation, but he planned to try it there and see what happens. Worst case scenario you're out a $35 sensor. However, he is planning to run his WBO2 in a 325is header port, not an S14.

                      My other concern was the stock location with coated headers. I'm not sure how well those coatings work, but the gas must be at least somewhat hotter on exit. Would this make the stock location even further from ideal?

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                      • #12
                        I'm running one at the X-pipe oriented at the 3 o'clock position, that is, parallel to the ground on the outboard side. In this position all of the gas is sampled, and the OE sensor is in place if you are running closed loop. I have a coated header and no heat problems, but I did put a small aluminum cooling fin on.
                        HTH,
                        Ron

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