Question for members with Stahl headers

[Markos]

Hi Folks,

I need to weld some 02 sensor bungs onto my Stahl headers. I'm thinking that cylinder #1 and #4 should do it. I only plan to run a single sensor but it will be nice to have the second during tuning. Would you be willing to check clearance against the inner fender and firewall and let me know what area works? I need to do this before I install the headers. Honestly I'm a ways out from installing but I'm restoring a second set and it makes sense to add bungs to both at the same time. Hopefully they can touch up the ceramic coating also. Not sure if this is possible.

 

[autokunst]

Hi Mark,
I have long pipe Stahl headers - is this what you have also? I can measure these areas for you when I am at the car next (either later this week or the at the end of the following week). Where on the primaries are you thinking of installing the bungs? Closer to the head, or closer to the collector? Without having the car here to measure, I can tell you I have about a country mile of space between the headers and the inner fender well.

Stephen

 

[Belgiumbarry]

why not after the collector so you have a mix of all exhaust ? For dial in a dual carb setup ?

 

[autokunst]

why not after the collector so you have a mix of all exhaust ? For dial in a dual carb setup ?

That's what I plan to do - a single bung/O2 sensor just rear of where the secondaries come together - in front of the center resonator...

 

[Belgiumbarry]

i also have it in the X pipe just ahead of the first mufflers.... with the webers . Perhaps with a dual carb it can be favorable you can measure on both....

 

[Markos]

Good question Barry. Stahl headers are long tube, so the collector is down near where the floor board meets the firewall. AEM only suggest that it is at least 18" away from a turbo, and before the cat. I don't have either of those to contend with. Keep in mind however that there is no collector that will capture all six pipes into one. On a factory setup, the first muffler is the collector. It has two inputs and one output. So I could run two bungs after each collector. I was thinking of just measuring #1 and #4 and ensuring that the carbs are tuned equally based on those readings. The advantage is that they are easy to get to when I want to switch between #1-#3 and #3 - #4 banks. Also, the sensor needs to be between 10PM and 2PM on the exhaust pipe. I'm not positive that I have enough room under the floorpan as the sensor would be pointed right at the floor. Hoping others can chime in on this.

Stephen - I will most certainly be seeking some input from you on this. If I place them up closer to the head, it looks like it could be a tad tight between the primaries. I can probably just point them at 12PM though and not even worry about the firewall. Then I can use my own headers to answer the placement question. I also don't now where the firewall starts without looking at your pic though.

Sorry for the ramble...

 

[autokunst]

When (or before) I have the car/headers in front of me, let's chat more about your ideal/preferred locations for these. I can mock it up, measure, and snap pics for you (at least how they might be situated on my car/headers).

 

[Markos]

When (or before) I have the car/headers in front of me, let's chat more about your ideal/preferred locations for these. I can mock it up, measure, and snap pics for you (at least how they might be situated on my car/headers).

Perfect!

 

[autokunst]

I feel like I have seen O2 sensors mounted horizontally (in the 3pm or 9pm position). And a quick interweb search seems to support that. But another potential option might be a specialty angled bung fitting like this:

Not sure how this affects the readings, if at all.

 

[Bert Poliakoff]

Maybe Don will chime in. I spoke with him on this very matter a week or so ago and his answer was only one sensor needed. I have a set of long tubes laying around and was curious just in case. I am running without a cat

 

[Markos]

I just got off the phone with the header shop
that will be putting the bungs on. He said that they mostly stick them in the collector, one on each. Dunk shops will swap the wideband as needed. I think I will go this route.

FWIW - a bung and plug is about $12 from AEM. The shop charges $30 installed. They are doing other work for me so I’ll go that route.

 

[autokunst]

Sort of a related topic, and I don't mean to hijack this thread, but I have been talking with a custom header shop about replicating my original Stahl long pipe headers in stainless steel. The intent would be to match all of the pipework, geometry, etc - but in 304 stainless and with merge collectors in lieu of the original formed collectors. I think there would be an economy of scale if they ran a "small production batch" of these rather than making just one for me. I will start a separate thread - I am curious if others would be interested in buying a new, stainless "Stahl" long pipe header. Of course, I would have a bung installed appropriately (which brings me back to the topic of this thread)...

 

[Markos]

Funny I asked the same thing. He said it takes at least 15 sets to cover the jig. Don't start a thread before I sell my second set of Stahls.

 

[Bert Poliakoff]

I spoke with a fellow in the Boston area who I believe made the long tube headers for Bavarian Auto Sport. I think he told me he made them in 2" or 1 3/4" $850 a pair. I also am not sure he knew the difference between E12 and E28 fitment. I also spoke with one of the fellows that works for the company that now has the Stahl jigs and they were talking $1150 a pair. I do have a set of 1 3/8" long tube headers I believe are from Bavarian and the extensions from the collectors . I think these came from an E12 and could always be used as a mock up. I bought them quite a while ago from an E12 fanatic.

 

[Stevehose]

They are mounted between 8 and 4 (top side) to avoid condensation in the pipe. If you have one afr unit and 2 O2 sensors you'll need to recalibrate the computer each time you switch pipes. I vote for one sensor.

 

[Honolulu]

Watching this with some interest.

If you recalibrate the operative sensor each time you switch from one to the other, you won't know that they both zero at the same point, thus losing the (I think) intended purpose of two sensors. Unless you believe the sensors function identically. If the sensors were established to (or you believe that they) function identically, you wouldn't need recalibration.

At a steady and repeatable rpm and load (if there is such a thing), how steady is sensor output with carbs?

 

[Markos]

They are mounted between 8 and 4 (top side) to avoid condensation in the pipe. If you have one afr unit and 2 O2 sensors you'll need to recallinrate the computer each time you switch pipes. I vote for one sensor.

Good point Steve. I’d save at least $30 also. I was just thinking of adding the bung and moving the single sensor as needed (and burning my hand). My gauge is calibrated to 1 lambda which is what the reset controller would be. Either way I don’t want to have two controllers with one gauge.

 

[Stevehose]

Very steady

At a steady and repeatable rpm and load (if there is such a thing), how steady is sensor output with carbs?

 

[Stevehose]

For on the road feedback you'll want the average of all i would think. Tuning is a small percentage of gauge use for me.

Good point Steve. I’d save at least $30 also. I was just thinking of adding the bung and moving the single sensor as needed (and burning my hand). My gauge is calibrated to 1 lambda which is what the reset controller would be. Either way I don’t want to have two controllers with one gauge.

 

[Markos]

For on the road feedback you'll want the average of all i would think. Tuning is a small percentage of gauge use for me.

Yes it seems like a one time thing. I’ll get a bung on each collector but the odds of using both a unlikely. I can’t get an average of all until behind the first muffler. That seems a bit too far down to me.