If there is no difference in flow with or without catalytic converter, why don't the o2 sensors crosstalk (blend) before converter is removed???

 

Ok, TTT

 

The material that makes up the cat keeps them separated.

 

Really???

 

The 02 sensors in my 12 came before the cats, so it should make no difference if you take away something downstream.

Kinda thinking this cross-talk think is an urban legend. Some tuners disconnect the 02 sensors altogether.

 

Thanks for the replies, just thinking outside the box, ride safe- later,,

 

Having gutted many HD head pipes I can tell you that the front head pipe extends into the collector 4 1/4 inches from the center of the front o2 sensor bung. The rear pipe extends into the collector 3 1/4 inches. This separation of gasses keeps the sensors from cross talking regardless of cat or no cat. This is at least as much separation as any aftermarket head pipe I know of. IMO the HD headpipe works as well if not better than any aftermarket headpipe on a stock engine. When cams are changed to performance camshafts then a noticeable performance gain can be obtained by installing a aftermarket performance headpipe.

 

One consideration is reversion; even though the cat does not pose a significant restriction to the exhaust flow, it does create a sort of 1 way valve, when it is removed fresh air is free to get sucked back in between pulses and cause errant readings.

 

And that is why having Wide Band o2s at each head is such a good idea (instead of prior to the cat). As the fresh air attempts to migrate into the heads, the sensors adjust accordingly. HD is doing what it can to please the EPA.
On most cars, there are o2s at the head pipes as well as just prior to the Cat/s.

 

You're exactly right.