O2 Bung Location?

clintonvillian

Famous Member
The Holley HP system only allows for ONE O2 sensor, where should it be located?

Secondly, if one were to go full SEFI using the above system should I place a bung in each collector and move the sensor from collector to collector while "fine" tuning each cylinder?
 
clintonvillian":po9wj1vi said:
The Holley HP system only allows for ONE O2 sensor, where should it be located?
In the header collector, just before it bolts to the rest of the exhaust system.
clintonvillian":po9wj1vi said:
Secondly, if one were to go full SEFI using the above system should I place a bung in each collector and move the sensor from collector to collector while "fine" tuning each cylinder?
That sounds like it would be both miserable AND dangerous to the other 5 cylinders. If you are not tracking total engine performance how do you know what is going on with the rest of the motor?
 
clintonvillian":1m0cguxk said:
The Holley HP system only allows for ONE O2 sensor, where should it be located?

Secondly, if one were to go full SEFI using the above system should I place a bung in each collector and move the sensor from collector to collector while "fine" tuning each cylinder?

You could also get a second O2 sensor and then use a toggle switch to change from the front collector to the rear. Good luck :nod:
 
CoupeBoy":29g28gqk said:
clintonvillian":29g28gqk said:
The Holley HP system only allows for ONE O2 sensor, where should it be located?
In the header collector, just before it bolts to the rest of the exhaust system.
clintonvillian":29g28gqk said:
Secondly, if one were to go full SEFI using the above system should I place a bung in each collector and move the sensor from collector to collector while "fine" tuning each cylinder?
That sounds like it would be both miserable AND dangerous to the other 5 cylinders. If you are not tracking total engine performance how do you know what is going on with the rest of the motor?


I think Bubba hit it on the head with the switch. However what about adding an X pipe right behind the collectors and dropping on in there?

As far as checking each cylinder, you would have to have the thing tuned as good as you could with it in the collector then move it up to each individual one to fine tune it. I am pretty sure this is done. Just haven't found anyone who has done it. If you notice, some headers have them built in just a bit down from the flange on each cylinder.

It wouldn't really be anymore dangerous than just having one in a collector only reading three cylinders, and not knowing what the other three are doing.
 
I would assume Holley would use a wideband, no? I thought those were best mounted a few feet back from the cyl head which (hopefully) would be spec'd out in the mounting instructions. I've never seen headers with individual O2 bungs near the flange on each cyl - thermocouple mounts, yes; but not for O2s.
 
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