2nd o2 senser on ssi conversion?
 

I'm considering replacing my stock exhaust with either ssi or 993 heater boxes and want to know, do I need a second o2 senser , and if so how is it wired?

You don't mention the 911 model or year that you're working with...but if you only had 1 sensor that reads a combination of 3 cyls' mixture...you don't need a second sensor. I guess this would be a different answer if you originally have a "fore" and "Aft" pair of sensors so differential readings are "fed back" to the computerized engine controls. In that case....if you "had" 2.... you'll still need 2.

- Wil

Sorry it's an '87 3.2

So...I think you can use 1.....

Wil

993 HEs don't have a bung for an O2 sensor. The O2s sensors are after the HEs. I had two bungs added to my muffler immediately following the HEs. I use one for the computer and plug the second, but planned to install a WideBand O2 sensor for tuning.

993 HEs should result in less backpressure and more HP than SSI, possibly at the expense of mid-range torque, depending upon your engine displacement and cam selection.

You can see the O2 sensor and capped bung in this photo:
Ben from M&K Exhaust made the muffler. He posts as MB911 on this board.

http://forums.pelicanparts.com/uploa...1156186590.jpg