O2 ?

[rod]

my O2 sensor is 8 1/2 inches from the end of the collector. Is that too close? I can make a collector extension [might help low end, so that would be a +]-if so, how much longer? or will it be OK as is?
this is the only place it can be, so I can't move it to a more favorable position
thanks
Rod in AZ

[Timetraveler]

Rod your O2 needs back pressure to work. I don't believe in using an O2 gauge to dial your car but it can save your engine if your going lean at high rpm. Do your testing with a long extension or a muffler and get your reading. Then run your extensions with a paint stripe and cut at the end of the paint burn. 'OLD SCHOOL'

[Ed Wright]

Originally Posted by rod

my O2 sensor is 8 1/2 inches from the end of the collector. Is that too close? I can make a collector extension [might help low end, so that would be a +]-if so, how much longer? or will it be OK as is?
this is the only place it can be, so I can't move it to a more favorable position
thanks
Rod in AZ

They do not need back pressure. That is, however, closer to the end than I would run it. I put mine right at the end of the transition. That is only good for WOT. To use the O2 for part throttle (I.E. return road) you need an extension. A muffler works well, or a 24" extention. I have a 24' with a 45 deg bend about half way. Reversion during the overlap cycle will pull clean air back in at low RPM & loads. Looks very lean on the O2. Works OK @ WOT.

[Bruce Fulper]

Originally Posted by Timetraveler

Rod your O2 needs back pressure to work. I don't believe in using an O2 gauge to dial your car but it can save your engine if your going lean at high rpm. Do your testing with a long extension or a muffler and get your reading. Then run your extensions with a paint stripe and cut at the end of the paint burn. 'OLD SCHOOL'

Does NOT work. Never did. You can cut your way all of the way to the cylinder head. Air changes. Not a reliable test. Leave it where it's at. You're making your own relationship to any changes anyway.