O2 logger bung placement

69427 · Post by **69427** » Sat Dec 27, 2008 8:43 am

I just bought a DL-32 data logger for our bracket car with a wide band O2 and a single EGT with extra bungs for booth so I can move them to different locations. I want to get the best overall tunning info.
Would you do the EGT and the O2 in one primary tube. Or the EGT in a primary tube and the O2 in the common collector.
Any locations or deminsions to be concerned with. This is a BBC.
Thanks
Tom

David Redszus · Post by **David Redszus** » Sun Dec 28, 2008 12:08 pm

Your first consideration regarding O2 placement is temperature. The sensor has a maximum temperature limit, which when exceeded, will substantially shorten its useful life.

Your sensor supplier should have provided the necessary temperature limit information to you. If not, ask for it. If they don't have it, buy from someone who does.

O2 placement in the collector will tell you only what the average readings are for all collected cylinders. Some may run lean, some rich, you'll never know.

If only one O2 sensor fits the racing budget, then buy extra bungs for each pipe and move the sensor from pipe to pipe. This will give you some idea of the mixture balance.

The location of the EGT will depend on the tip syle of the sensor. A closed tip must be mounted close to the port in order to reduce the response delay time. If an open tip style is used, it can be mounted close to the O2 sensor. If at all possilbe, one EGT should be fitted to each pipe.

Since the accuracy of the O2 sensor is dependent on temperature, placing an EGT close to the O2 sensor will provide some idea of the operating temp of the O2 sensor (and its limits of accuracy).

Before going too far down this road, ask yourself: exactly what information will I get from each sensor? What exactly will they tell me?

Rod · Post by **Rod** » Sun Dec 28, 2008 6:13 pm

will lifting to Lambda / O2 sensor out of the direct exhaust flow by fitting taller bungs effect the reading of the sensor

regards
rod

Brian P · Post by **Brian P** » Sun Dec 28, 2008 7:20 pm

Yes ... the tips of those sensors are supposed to be in the flow stream.

Beretta · Post by **Beretta** » Sun Dec 28, 2008 10:28 pm

Place the 02 about 8" from the end of the collector and anywhere from 10 to 2 o'clock and 12 o'clock being the best spot. As for the EGT you should have 8 one in each cyd but if you can't do that, 4 will do the job but you will need bungs in all 8 tubes... Start with the EGT's in cyd 1and 2 and 7 and 8 as there are always your lean cyd...

What do you have as far as a carb??? List # hp or not???

David Redszus · Post by **David Redszus** » Sun Dec 28, 2008 11:39 pm

will lifting to Lambda / O2 sensor out of the direct exhaust flow by fitting taller bungs effect the reading of the sensor

Long reach O2 sensor bungs are often used when very high exhaust temperatures are expected.

Moving the sensor tip away from the high velocity centerline air stream will slow the sensor response but that is sometimes necessary for survival.

Sensors ideally should be mounted in a near horizontal orientation (actually about 10deg above horizontal) if at all possible.

Another frequently overlooked consideration is the hex temperature of the sensor. The maximum hex temp is about 700F lower than the max tip temperature. When the pipe wall temperature is excessively high, it becomes necessary to fabricate a sensor bung out of 304 stainless. The thermal conductivity of stainless is about 1/3 of carbon steel.

Doug Schriefer · Post by **Doug Schriefer** » Mon Dec 29, 2008 2:16 pm

Rod wrote:will lifting to Lambda / O2 sensor out of the direct exhaust flow by fitting taller bungs effect the reading of the sensor

regards
rod

It will affect the response time, and life of the sensor. The main thing you have to keep in mind is that you're not really concerned with the exact number, just what the number has to be with your particular setup, and how it changes with weather and tuning.

Doug Schriefer · Post by **Doug Schriefer** » Mon Dec 29, 2008 2:17 pm

Beretta wrote:Place the 02 about 8" from the end of the collector and anywhere from 10 to 2 o'clock and 12 o'clock being the best spot. As for the EGT you should have 8 one in each cyd but if you can't do that, 4 will do the job but you will need bungs in all 8 tubes... Start with the EGT's in cyd 1and 2 and 7 and 8 as there are always your lean cyd...

What do you have as far as a carb??? List # hp or not???

Don't know that I would say that with a properly set up intake manifold!

Beretta · Post by **Beretta** » Mon Dec 29, 2008 3:59 pm

Doug Schriefer wrote:
Beretta wrote:Place the 02 about 8" from the end of the collector and anywhere from 10 to 2 o'clock and 12 o'clock being the best spot. As for the EGT you should have 8 one in each cyd but if you can't do that, 4 will do the job but you will need bungs in all 8 tubes... Start with the EGT's in cyd 1and 2 and 7 and 8 as there are always your lean cyd...

What do you have as far as a carb??? List # hp or not???
Don't know that I would say that with a properly set up intake manifold!

Im going by what he has posted for this combo...So I guess I should say usually 1&2 7&8 are your lean cyd....

Doug Schriefer · Post by **Doug Schriefer** » Mon Dec 29, 2008 4:04 pm

Beretta wrote:
Doug Schriefer wrote:
Beretta wrote:Place the 02 about 8" from the end of the collector and anywhere from 10 to 2 o'clock and 12 o'clock being the best spot. As for the EGT you should have 8 one in each cyd but if you can't do that, 4 will do the job but you will need bungs in all 8 tubes... Start with the EGT's in cyd 1and 2 and 7 and 8 as there are always your lean cyd...

What do you have as far as a carb??? List # hp or not???
Don't know that I would say that with a properly set up intake manifold!
Unless there is a problem with the intake or carburetor 7 & 8 are normally richer on most Drag race engines due to acceleration forces.

Im going by what he has posted for this combo...So I guess I should say usually 1&2 7&8 are your lean cyd....

69427 · Post by **69427** » Mon Dec 29, 2008 7:57 pm

DAVID REDSZUS QUOTE O2 placement in the collector will tell you only what the average readings are for all collected cylinders. Some may run lean, some rich, you'll never know.

If only one O2 sensor fits the racing budget, then buy extra bungs for each pipe and move the sensor from pipe to pipe. This will give you some idea of the mixture balance.

[/quote]

Yes only one O2 in the budget for right now but I can expand this system. I was thinking of a bung in each collector for an overall reading and one in each tube just befor the collector (type of sensor) to to monitor an indvidual cylinder along wih the one EGT probe.

69427 · Post by **69427** » Mon Dec 29, 2008 8:17 pm

Beretta wrote:Place the 02 about 8" from the end of the collector and anywhere from 10 to 2 o'clock and 12 o'clock being the best spot. As for the EGT you should have 8 one in each cyd but if you can't do that, 4 will do the job but you will need bungs in all 8 tubes... Start with the EGT's in cyd 1and 2 and 7 and 8 as there are always your lean cyd...

What do you have as far as a carb??? List # hp or not???

I only have one EGT in the budget right now so I am going to have to move it around at first. After reading your post, if I get 3 more EGT's we can monitor all four exhaust tubes that that supply the collector that the O2 is in.

I really can't tune cylinder to cylinder no digital 7

The carb is a Pro Systems sitting on a victor junior.

Beretta · Post by **Beretta** » Mon Dec 29, 2008 8:41 pm

You have a pm