2018 FXBRS O2 Sensor placement

[45bpcr]

I say "placement" for a reason.
I recently installed a S&S SuperStreet (no cat) on my FXBRS.
The pipe has 12mm O2 bungs in about the same location as the factory header pipes.
It also has 18mm bungs for wide band sensors very close to the exhaust ports and came with 18 to 12mm adapters.
Would there be any advantage in re-locating the factory narrow band sensors closer to the exhaust ports in the 18mm bungs using the supplied adapters?
I'm using a Powervision PV-2B and have been working with the Autotune feature after starting with one of their canned tunes.
Other than the pipe and a better air filter, it's a stock motor.

I want to get wide bands in the future, but need to re-coup after buying the exhaust, tuner, new brake pads and tires, perhaps next month :-)

Thanks in advance,
Craig
 

[Tacocaster]

No Cat? I thought the Super Street is manufactured with a cat?

I'd ask S&S. They provided the two mount points. Ask why they did (Race only, I'd bet for the close-to-exhaust-port one) and what would they suggest for your application. Last time I asked them a simple question they didn't bite and were quite helpful. after all, they want you satisfied.

Either way, a sensor placed pre-collector (primary pipe install) can cause tuning issues at idle where outside air is mixed thru reversion pulses, but again, S&S are the experts on their products.

[lonewolf]

I would use the 12mm bungs. The adapters can pull the o2 out of the stream. The 18mm's closer to the port are usually for the older none heated o2's. I'd rather spend the money on a good tune and keep the narrowbands. The PV and SE broadband kits are not as good as some think.

[kd]

I have both bungs as described in my Burns pipe.  The wide band fittings close to the heads are placed there for tuning only (in my case at least).  We tuned with narrow, wide and also copper AFR tubes inserted to mid way between the )2 sensors for sampling and confirming when tuning only. The wide bands (and copper tubes of course) are removed and plugged after tuning leaving only narrow bands near the OEM position.  I didn't think it was possible to run both unless as I described on a dyno drum with a computer.  FWIW I am using TTS (blue)..

[45bpcr]

I appreciate the input.
The sensor protrusion using the adapter bungs was a concern of mine as well.
They're so tiny for a 4 wire sensor, we all kinda chuckle about them at the shop.

This is the pipe I installed.

https://www.denniskirk.com/s-and-s-cycle/ceramic-black-superstreet-2-into-1-exhaust-system-550-0857.p4410906.prd/4410906.sku

I ordered it 7/7/24. At that time it was priced at $928.00 shipped.
I see it's now the same price as the 50 state version that has a cat. I wonder if S+S is suffering the wrath of the EPA for offering a cat-less pipe. I can no longer find it on their web site either.

So far I've done several auto tune sessions riding under every condition I can. I've saved them in their own slot, overwrite them with each session, then re-flash the bike.
The bike seems runs really nice now.
Using a Db app on my phone (NIOSH SLM) idle sound level is 107 and no load high revs are 137 so it's fairly quite at idle and cruise.
So far, I'm pretty happy.

C

[hrdtail78]

Heat kills o2 sensors.  We had to use exhaust gases to heat up the older narrow bands, but this had negative impact on tolerance of error and service life.  The answer was to heat the sensor another way so they could move it out of the intense heat coming straight out of port.

Remember the strategy of use for these sensors.  Steady state that needs an average of constant data to make a change to long term or adaptive.  While most use a style of heated wide bands closer to the port for transient fueling such as acceleration roll ons.  Closer we are to port.  Less delay on sensor picking up the the changes needed as it climbs in rpm.

If you look at the improvements of the different models of LSU's through the years.  The improvements of the sensor themselves have been biased toward handling temps and pressure better.  The latest of 4.9's being the 4.9T.