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O2 Sensor Location?
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Author:  Ken0069 [ Sun Nov 06, 2011 3:04 pm ]
Post subject:  O2 Sensor Location?

As most of you already know, I've got my engine and stuff in this "new to me" dragster and now I'm looking at installing some weld in bungs in these new headers for O2 sensors. I've talked to Barry about what location his are in but I've come to the conclusion that I want to put 8 of'em in so that I can move sensors around to every exhaust pipe and where Barry has his won't work for me the way I have to mount my LC-1s. So if I put these O2 sensor bungs in on each exhaust pipe, how far from the head do they HAVE to be in order to work? I ask that question because I also have EGT thermocouples that have to be mounted and they will go in 2 inches out from the cylinder head.

Author:  shrinker [ Sun Nov 06, 2011 3:31 pm ]
Post subject:  Re: O2 Sensor Location?

The sensor needs to be in a gas stream where the temperature is below 800C.

Author:  Ken0069 [ Sun Nov 06, 2011 4:26 pm ]
Post subject:  Re: O2 Sensor Location?

800*C is = to 1472* F so I guess 4 inches out from the EGT thermocouple (6 inches total from the head) will be fine, and that's something I can do with these headers. The only time this engine sees anywhere near that kind of temp is on gas and since that O2 will be 4 inches down stream of the thermocouple it's likely to see less than that. And, on methanol it's way below that too.

I want to mount the LC-1s on the frame next to the engine and if I can do that I can reach all 4 locations/side if the weld bungs are 6 inches from the head.

Thanks.

Author:  shrinker [ Sun Nov 06, 2011 4:54 pm ]
Post subject:  Re: O2 Sensor Location?

Putting them after the bend should be fine. The sensor can be in colder gas as its got its own heater inside it to maintain its temp at 800C. When there on dynos there in the downward section of the primary pipes, like on the outside of a sprintcar exhaust sort of.

Author:  Ken0069 [ Sun Nov 06, 2011 8:21 pm ]
Post subject:  Re: O2 Sensor Location?

ALL these bends in these headers are 6 inch radius so the weld bung locations won't actually be on the DOWN turn of the pipe per se. They will be down "some" but not anywhere near as much as a sprinter header, which usually has 3 inch radius bends at the head.

Image

Right now I've got #6 thermocouple 2 inches out from the head and on methanol it's reading 1130 +/- degrees at the eight mile. I can't imagine gas being over 1400 in that short of a distance especially since Barry's BBC is about 70 degrees less than that at the eight mile on gas.

I can get a complete set of bungs and plugs from Greg Kelly at Motorsports Innovations for less than $30 so I think I'll go ahead and get them so I can put those O2 sensors on any cylinder I want.

FOFG \:D/

Author:  shrinker [ Mon Nov 07, 2011 4:25 am ]
Post subject:  Re: O2 Sensor Location?

Check the length of the bung, because the sensor pokes into the pipe if its a short bung. Not what you want to do in a primary.

Author:  dieselgeek [ Fri Dec 16, 2011 6:48 pm ]
Post subject:  Re: O2 Sensor Location?

800C ???

I thought the Bosch LSU sensors were set for a max of 900 degrees *farenheit* ?

might want to double check Shrinker's info. Those sensors do NOT work in 1400 degree EGT for more than a few seconds.

Author:  dieselgeek [ Fri Dec 16, 2011 6:54 pm ]
Post subject:  Re: O2 Sensor Location?

Q: When do I need to make or install a heat sink?

A: The Bosch LSU4.2 wide-band O2 sensor (shipped as part of the LM-1 kit) is rated to operate at an exhaust gas temperature of < 1300 degrees (F), and a sensor housing temperature of < 900 degrees (measured at the bung) for maximum accuracy and control. When either of these operating temperature ranges is exceeded, the sensor can no longer be accurately controlled. Further, operating at or over these temperatures for any length of time can significantly reduce the lifetime of the sensor. The LM-1 is designed to display an error message under these conditions (currently 08- Sensor Timing Error) rather than provide inaccurate readings. For some turbo vehicles, rotary engines, and other setups, this error message can be encountered with annoying frequency.


That's from the LC-1 support page.

Author:  shrinker [ Sun Dec 18, 2011 12:25 am ]
Post subject:  Re: O2 Sensor Location?

From Bosch spec sheet of the sensor used by innovate

2. Application conditions
For all temperature measurements refer to
section 3: test methods.
2.1 Temperature range, passive: -40°C ... +100°C
(storage temperature)
2.2 Operating temperatures
Exhaust gas at sensor element: ≤ 930°C
Hexagon of the sensor housing: ≤ 570°C
Cable grommet (PTFE formed hose)
- sensor side: ≤ 250°C
- cable side (upperhose crimp): ≤ 200°C
Cable and protective sleeve: ≤ 250°C
Connector: ≤ 120°C
2.3 Maximum temperatures (max. 250 h accumulated over lifetime)
Exhaust gas at sensor element: ≤ 1030°C
Hexagon of the sensor housing: ≤ 630°C

I have used them in location of high temperature with no issues. The sensor location your considering will work. If you get error 8 its not because of temperature its because of tune and gas conditions loading the cell.

Author:  shrinker [ Sun Dec 18, 2011 2:29 am ]
Post subject:  Re: O2 Sensor Location?

From innovate support site.
"Q: After testing the unit out at idle for ~10-15 minutes I got a sensor timing error. I turned off the LM-1 and cycled it back on and it's been fine since. Is this anything to worry about? What causes this error?
A: The Bosch sensor runs optimally at 750-800 deg C Sensor Temp. If the sensor head gets heated by the exhaust to that temperature or above there is no more margin for the heater controller and it runs essentially 'open loop', shutting the heater off. "

Within the innovate system design the shut down temp is 800C Although the sensor can operate at higher they choose to shut down due to it not being "Digitally accurate" information above 800C.

Author:  Ken0069 [ Sun Dec 18, 2011 9:08 am ]
Post subject:  Re: O2 Sensor Location?

800 degrees Celsius = 1472 degrees Fahrenheit and with the bungs around 8" down the pipe, that should keep it under that max operating temperature.

Thanks guys.

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