CT4-V CT4 BW ARH Downpipes

[Todd]

The primary cats are further upstream, closer to the turbos (untouched). The down pipes only contain the secondary cats.

Ok, looking into this further, I can see that there may be confusion here.

I can even tell from the thumbnail of this video that there are secondary cats.

Common misconception, as the OE “cat assembly” looks like one big cat, but there is an air gap between the primary and secondary stage. That’s where the second O2 sensor sits.

Aftermarket dps replace the primary cat with a higher flowing one and delete the secondary (they aren’t monitored by O2 sensors, so they can be deleted without a CEL).

I don’t know of any modern US market gasoline car that doesn’t have secondary OE cats, they are there for cold running emissions control.

 

[Kawman]

Just because it's on the internet doesn't mean it's true, but.....

Where are the 4 catalytic converters on a Cadillac CT4-V Blackwing?

AI Overview

The 4 catalytic converters on a Cadillac CT4-V Blackwing (3.6L Twin Turbo V6) are located
in the exhaust system directly off the engine. There are two "primary" cats bolted directly to the outlet of each turbocharger (driver/passenger), followed by two "secondary" cats located further down the exhaust pipes,.

• Primary Cats (Pre-cats): Mounted directly to the turbocharger outlets on both the driver and passenger sides.
• Secondary Cats: Positioned further down the downpipes in the exhaust stream.

 

[Todd]

Just because it's on the internet doesn't mean it's true, but.....

Where are the 4 catalytic converters on a Cadillac CT4-V Blackwing?

AI Overview

The 4 catalytic converters on a Cadillac CT4-V Blackwing (3.6L Twin Turbo V6) are located
in the exhaust system directly off the engine. There are two "primary" cats bolted directly to the outlet of each turbocharger (driver/passenger), followed by two "secondary" cats located further down the exhaust pipes,.

• Primary Cats (Pre-cats): Mounted directly to the turbocharger outlets on both the driver and passenger sides.
• Secondary Cats: Positioned further down the downpipes in the exhaust stream.

Technically that description is correct. The secondary cats are positioned further down the exhaust stream (by 2”).

Typical cat assembly design.

 

[Kawman]

The OEM downpipes can be purchased today for $475 and $450. Hard to believe that after profit to the selling dealer, the material and labor cost to shape and weld the piping, there would be enough left for a more technical 2 stage cat assembly that contains palladium, platinum and rhodium.

 

[Todd]

The OEM downpipes can be purchased today for $475 and $450. Hard to believe that after profit to the selling dealer, the material and labor cost to shape and weld the piping, there would be enough left for a more technical 2 stage cat assembly that contains palladium, platinum and rhodium.

Secondary cats have less precious metal loading, they’re used mainly in conjunction with the primary cats during the warm up phase. Once the primary cats are up to temp, there is little demand on the secondary cats, that’s why they are unmonitored.

Further, because the primary cats take the brunt of the heat punishing from the engine combustion process, secondary cats can typically use a ceramic, vs metal, substrate, making them substantially cheaper to manufacture.

Secondary cats do very little of the overall catalytic work. But they are a federally recognized part of the OE emissions system.

 

[Todd]

Here’s the break down:

Purple arrow is the inlet, coming from the turbo outlet.

Green dot is the primary O2 sensor.

Light blue is the primary cat.

Yellow is air gap between the cats.

Red dot is secondary O2 sensor.

Dark blue is the secondary cat.

 

[TERRAVAST4]

Here’s the break down:

Purple arrow is the inlet, coming from the turbo outlet.

Green dot is the primary O2 sensor.

Light blue is the primary cat.

Yellow is air gap between the cats.

Red dot is secondary O2 sensor.

Dark blue is the secondary cat.

View attachment 33347

Yeah…. The CT4 Blackwing has two converters. Mine didn’t have rainbows on them but they are gone now

 

[ngoni]

Yeah…. The CT4 Blackwing has two converters. Mine didn’t have rainbows on them but they are gone now

I think only the special edition cars come equipped with the rainbow cats and polka-dot gas tanks.