2.5 TDI: R5 vs. V6 Loader Comparison

Hello,

Perhaps someone can enlighten me about that.

The A4 8E with a 120kW 2.5 V6 TDI engine (BDG) is equipped with a Garrett GT2052V turbocharger, with a part number such as 059 145 701 S.
This engine consumes 40mg of fuel per cycle at its rated power output, with a boost pressure of 2230 mbar absolute.

In contrast, the T4 with the 2.5 R5 TDI engine (AXG), which has an output of 111 kW, is equipped with a Garrett GT2252V turbocharger, with a part number such as 074 145 703 E.
This engine consumes 43mg of fuel per cycle (per cylinder) at its rated power output, with a boost pressure of 2050 mbar absolute.

Okay, here's the translation:

"Now, my question: why does an engine with more power, and therefore logically higher boost pressure, have a turbocharger with a smaller exhaust side?"

Since the compressor inlet side is the same, the GT2052V should theoretically spin faster to achieve the higher boost pressure.

With the same boost pressure but a smaller exhaust side, a larger exhaust enthalpy difference is required to achieve the same boost pressure .

EDIT: It should be mentioned that both engines are Euro3 compliant.

The compressor side is not the same. The GT2052V has, which somewhat contradicts the designation, a larger inducer than the GT2252V. Therefore, at the same speed, a higher maximum flow rate is possible.

Hi,

A turbocharger with a smaller turbine wheel allows for more dynamic control, while pressure changes with a larger turbine wheel occur more gradually. Additionally, the weight and, consequently, the rotational inertia of a turbine shaft are lower with a smaller wheel. This is also more suitable for a passenger car.

I suspect that with vans, you simply operate much closer to the soot limit than with passenger cars, which is why the boost pressure is kept lower. It would be interesting to compare the actual air mass values at rated power.

Best regards, Rainer.

Quote:

The GT2052V, which somewhat contradicts its designation, has a larger inducer than the GT2252V. Therefore, at the same speed, a higher maximum flow rate is possible.

Okay, that's obviously an aspect that I didn't consider due to a lack of knowledge .

Quote:

I suspect that with a van, you simply operate much closer to the soot limit than with a passenger car, which is why the boost pressure is kept lower. It would be worth comparing the actual air mass values at rated power.

That would mean that the van loader operates with significantly more reserve power than the car loader.

I only find datasheets and shell diagrams for the Garrett chargers without VTG. Does anyone know if the performance is still the same or comparable? I think such a diagram is much more informative.

http://turbochargerspecs.blogspot.co.at/2011/02/garrett-gt22-gt2252-60-trim-260-hp.html

https://www.turbobygarrett.com/turbobygarrett/turbochargers/gt2052

EDIT: When I compare the diagrams, it appears that the transporter loader is actually operating far away from its nominal power point. It seems that a much larger loader was deliberately chosen to operate it within the range around the efficiency maximum .

Okay, so you can completely forget about the diagram for the GT22; the GT2252V from the T4 only has an inducer of 36.8mm, which definitely doesn't match the wastegate version at all.
The GT2052V from V6, on the other hand, has a diameter of 38.6mm, which is a better fit.

"To my understanding, the GT22 was deliberately designed for the T4 to achieve a slightly higher pressure ratio in the lower and mid-range, simply because the V6 engine needs it more than the 2V engine (2 valves vs. 4 valves)."
Of course, reserves also play a role, as NFZ vehicles are optimized for a few kilometers more than passenger cars.

Hi,

I want to revive this thread.

Does anyone happen to have an "accurate" compressor map for the GT2052V? Online, you only find the wastegate versions for extreme tuning, or for various Chinese knock-offs .