O2 sensor question
 

This may be a stupid question, but I'm planning on buying a AFR gauge. I have euro headers on my '87 930. I know there is an O2 sensor in the header system already, do I mount the O2 sensor, that comes with the gauge, separately or does it replace the one that's already on there? If separately, do I have to add a bung or is there an extra bung already there? If I have to add a bung, what is the best location, in the header system, for it(next to the turbo, or by the wastegate, or what..)? My car is currently at the shop having the engine and trans rebuilt, and I'm making some changes to the engine, such as going from 100mm drop-in cylinders to 98mm and going from 7.1:1 compression to 7.5:1, and I don't want to have to spend this kind of money again soon because the AFR's were off.

I'm considering the AEM 30-4100 gauge

when I ran my wide band O2, there was an analog out for me to use to tie into the factory circuit. The wideband also functioned as a factory O2 sensor.

Ok, so I've done some more research, and I need to mount it past the turbo. I'm installing a RarlyL8 Zork tube. Will I have any problems with accuracy from an O2 sensor mounted in such a short pipe? Is this mounting ok?

The zork is only 3in dia and Rarlyl8 ox sensor bung is close to the turbo, I don't think that you will have any issues at all? Look at your instructions for the sensor, I would recommend building a heat shield as per their instructions (at least mine showed how to make it), there is a lot of heat just passed the turbo.

In a zork since its so short you may have reversion at idle and low exhaust flow so dont be surprised if idle readings are off. Maybe, maybe not.
However, once you're moving and have some exhaust flow the reading should be accurate.
You dont want the O2 sensor mounted before the turbo because it will burn up.
Making the heat sink is a good idea too. Innovate motorsports has good instructions on how to mount this under the sensor.
Make it out of copper if possible.

Fred

You need to post the dyno results when you get this thing finished.

I am interested in seeing what kind of power your mods put out.

Good luck,
Fred