2.0TDI AZV - Is a catalytic converter needed to reduce exhaust backpressure?

Best regards,

Deus Violentia wrote:

According to my understanding, the turbocharger should be able to rev higher without exhaust backpressure. However, I doubt that this would lead to a change in boost pressure, right? Even if it did, I believe the engine control unit (ECU) could compensate for it, as the parameter change would likely be within a range of 0.01 bar. What do you think? KAT for back pressure, if necessary?

Certainly, a certain amount of back pressure is of interest for optimizing valve timing and gas exchange in engines, and it is not necessarily true that a turbocharger without back pressure has a better efficiency. You should assume that a laminar flow around a turbine is most effective. The more this flow pulsates, the more losses occur when these rapid "impulses" hit the still very slow-moving turbine.

A healthy balance is interesting. Under certain circumstances, a pipe of a certain length (after the turbocharger's outlet) might have a positive effect. For example, I've had bad experiences with the wastegate being completely open, but I don't have any experience to share regarding the VNT (Variable Nozzle Turbine). In the current case, improved exhaust flow through the muffler has resulted in a significant improvement, which in a before-and-after comparison is approximately 3 times higher than when the particulate filter is fully loaded or freshly regenerated.

Deus Violentia wrote:

Oh yeah, why is the catalytic converter

located directly behind the turbocharger on the 2.0 TDI engine? "Is this to help it reach operating temperature faster, or does it have another purpose that I'm not seeing right now?"


Emission standard. For the reasons you described.