How bigga bunga

[BOZO]

Can anybody tell me what size designation the threads are on most oxygen sensors? I am installing a new exhaust in my project truck and I would like to put in bungs for the O2 sensors just behind my headers. My truck does not now have a need for these, but I may see a need for these in the future. I figure these can be bought but being a machinist on machinist pay, I'll just be making these myself.

[GCncsuHD]

Most are M18x1.5. At least that is the size on all OEM LSX exhaust setups, most aftermarket wideband o2's, and my dad's 2000 4cy S10 I had to make O2 simulators for.

Also, even being a machinist, I doubt you can make them for as cheap as you could buy a couple bungs from someone who mass produces them. Time is money...but if you are doing it on the company time, go for it.

Also, I can't remember the model car, but the oil drain plug from some Honda car fits perfectly in the bung as a o2 sensor plug.

[BOZO]

GCncsuHD

Thank you for the info. 18x1.5 is the size I've been hearing word of mouth.
The truck may never end up computerized, but I will be tuning the truck in the future with a wideband O2 gauge.

Which brings another question to mind. My exhaust will have a balance tube just behind the collectors. Would putting just 1 sensor bung in the center of the balance pipe be effective just to hook up an O2 wideband gauge?

[GCncsuHD]

Originally Posted by BOZO

GCncsuHD

Thank you for the info. 18x1.5 is the size I've been hearing word of mouth.
The truck may never end up computerized, but I will be tuning the truck in the future with a wideband O2 gauge.

Which brings another question to mind. My exhaust will have a balance tube just behind the collectors. Would putting just 1 sensor bung in the center of the balance pipe be effective just to hook up an O2 wideband gauge?

I don't see why not, although with one sensor you wouldn't be able to isolate problems to one bank or the other. Also by balance tube, I assume you mean H-pipe style? I think it would be better off mounting one sensor after a Y pipe, or in the center of a X pipe, I just feel that would get better direct flow than in the center of a H pipe, because come to think of it, H pipes don't really flow much exhaust gasses between the two sides, but rather operate using pressure waves to balance the exhaust out, whereas X and Y's physically mix the exhaust. But If I were you I would just weld a bung in each collector, and just run a plug in one, and the sensor in the other side. Then when you think you have a problem it would take 5 minutes to swap to the other side to narrow your problem down.

But I am no tuner/hot rodder, just do this for a hobby, I'm sure there are much smarter guys that will give you a better opinion on that.

[BOZO]

GCncsuHD

I agree with the missing flow in the H-pipe. May not return a proper signal.
I will probably put a bung in at all three places and just plug off what doesn't suit me.