I don't see how you won't end up with stagnant air in the pipe. Stagnant air will not give an accurate reading. I could see if there was a way to get the exhaust in one end of your tube and out the other, but not having the sensor in a dead end tube, especially one that is that long. The 90* adapters affect the reading, how could a 30" tube not affect it?

FWIW, I have put bungs in about 10 sets of Lightening Headers going back about 10 years. Maybe they have recently changed something, but we have never had an issue.
Eddie

I used to sell gas analyzers when I worked for Snap-On. They had the probe that stuck up the exhaust a couple feet and a hose going to the machine. Here is the problem. There is a very long delay in real time between the sample and the reading, around 15 seconds if I remember correctly, but the computer corrected this so that you didn't really realize it. These machines also had a pump that pulled the exhaust in. I am afraid that if your idea does in fact give accurate readings at all, that there will be a delay in the reading and if it is only a couple tenths of a second it will render it useless to your tuning.
I think if it is a standard bravo exhaust system, I would just find a set of cheap used headers and install the bungs correctly, tune it and put your good exhaust back on.

I have gotten away from the dead end tube idea. Tube will be open on both ends with the bung installed in the same fashion that you would install it in an automotive exhaust (poking thru the side of the pipe). Front of the tube will terminate about 2" behind the collector. rear of the tube will terminate 24" behind my exhaust tips. Tube will be open on both ends. Then I drill a hole in the tube and weld on the bung. I am hoping for a good flow of exhaust through the tube.

Lightnings reasoning for not drilling and welding on the headers is they said it would disrupt the ceramic coating inside the tubing. If this sniffer tube idea does not work I am going to install the bung in my headers anyways.






I am certainly no expert on any of these subjects. This is just an experiment for me that will cost next to nothing to try. I appreciate everyones advice and comments.

I was under the impression that Lightning uses a stainless inner pipe on their headers. Guess they are talking about the inside of the outer pipe, which I believe is made of mild steel.

If you can get sufficient exhaust flow, it seems to me that it should work. I would go with the largest diameter pipe that you can manage to put in there. Hell, if you could stuff a 2 1/2 inch piece of exhaust pipe up in there with a bung welded into it, that would seem to me to be ideal.

As far as lag time on the O2 readings, aren't we talking about doing this temporarily so you can tune it at different engine speeds? You are just trying to jet the carb to give you the best possible AF mixture at idle, cruise, 3/4 throttle, WFO, etc., right? This is not an EFI application that is metering fuel flow based upon the AF readings, so even if you are lagging behind 15 seconds, it shouldn't matter. I know that some OSO'ers are running full time AF gauges in their boats so they can keep an eye on things, but it's not in the cards for all of us. The idea here is to make sure there are no hidden lean spots that could get you into trouble, right?

Here's a question for folks who have experience with O2 sensors - does water ruin them only when they are powered up and hot, or are they ruined if any water gets on them at all, even when no power going to them?

Water ruins them period. They should always be powered up when the engine is running. Leaving them in without being powered up will kill them as well

That I do not know.

OP, if/when you kill the sensor and its a Bosch, NGK, or NTK you can get a replacement sensor here, cheapest I have found anyway...

http://oxygensensor.net/

Lightening has 2 sets of headers with different make ups. Both have stainless inner, 1 has a mild steel ceramic coated outer from my understanding, and then they have an all stainless set.

Thanks !

I think the ONLY way you are going to get them to live with lightnings is run them dry..and that they say won't work either, I even tried setting up a dump from the log drains to a fitting in the Y-pipe to reduce the water while tuning...saw no rise in temp and still killed the 02 within mins...this deal has been beat to death, but in our case could get them to live while idling, cruise & moderate runs, but on a WOT run and you back off, must suck enough water in kills them dead, after a couple even tried backing down slow...still DOA, now some headers will work out of the box with 02's I've been told, but with our lightnings w/silent choice(no do not run with that on) the water dump is right behind the collector where the 02 is..