2,5TDI: Teile in der Ölwanne | Posts 32+

Quote:

Because otherwise, you would never achieve such a beautiful torque curve.

I think it's more about the emissions performance. The V6 TDI engine was always a very "clean" engine in terms of power and weight (EU4 standard without a DPF in the C5 quattro!). "You can tell by the amount of soot produced and the sluggish acceleration compared to the 4-cylinder engines."
The MB A-Class had a 4-valve engine for the diesel version, but a 2-valve engine for the gasoline version, not because of performance, but due to emissions regulations. The loader takes care of the filling.

Best regards,

Albrecht wrote:

I think it's more about the exhaust emissions.

Well, it wasn't particularly special at the AFB either. And the EURO 4 models don't really have much to do with the AFB anymore, because the engine block itself is no longer the same.

I believe it was mainly done for the torque. If not, they certainly wouldn't have put a swirl channel and a filling channel in there; they would have designed both as filling channels instead. The GT20's responsiveness isn't exactly the best, even with VTG.

And 4V technology isn't required for EURO 4 compliance, as evidenced by engines like the AXR and BUK. There are 8V engines that meet EURO 4 standards without a DPF, and in the case of the BUK, even with a significantly higher power output.

Power/Torque:
The torque curve, along with the corresponding power delivery and engine smoothness, are truly top-tier for a diesel engine – a real textbook example. That's absolutely right! But...
2.5L displacement with four-valve technology, VTG turbocharger with over one bar of boost... etc... and then only 150 horsepower... um... yeah... I mean, how inefficient does that engine have to be? Have you ever put it in neutral while going downhill and looked at the instantaneous fuel consumption? Wow, you wouldn't believe how much diesel fuel that engine alone burns just for self-powering... probably because it's packed with so much stuff.

Exhaust emissions: The engine is remarkably verschandeln considering what it consumes. As far as I've observed, 2.5L TDIs rarely produce soot. The 1.9L engines, for example, are more prone to it. Also, the effort required to meet the Euro standards is actually quite low. However, this is more a reflection of the standards themselves than of the actual emissions. My assessment...


Best regards, Marcus.

Quote:

And 4V technology isn't required for EURO 4 compliance, as evidenced by engines like the AXR and BUK. There are 8V engines that meet EURO 4 standards without a DPF, and in the case of the BUK, even with a significantly higher power output.

You are forgetting about the vehicle weight in all of this.

I recommend consulting relevant technical literature on the subject (e.g., www.all4engineers.de).

Best regards,

"But I also find it quite interesting why the 2.5 TDI engine became so heavy... If you look at the engine block itself, it seems quite compact. So, it's more the components and structure surrounding it that contribute to the weight. It seems like weight wasn't really a major consideration during the development process." That kind of damages the engine in a way... or rather, it compromises what you gain from the increased displacement.


Best regards, Marcus.

Here's some additional information about that:

Source: http://ww2.autoscout24.de/vorstellung/audi-q7--neue-technik/acht-gaenge-statt-acht-zylinder/4319/167717/?magcid=mag-nl&extcidm=DE-NL-7-CW14-2010

Audi has also redesigned the 3.0 TDI diesel engine, which, according to the manufacturer, only shares its power output with its predecessor: 240 horsepower and 550 Newton meters of torque. However, the torque is now available from just 1,750 revolutions per minute. During the renovation work, the weight of the V6 diesel engine has decreased from 20 to 198 kilograms.

The 3.0-liter engine was already lighter than the 2.5-liter engine. Generally, that's not possible if the base was already "very good" .

Best regards,

Albrecht wrote:

The 3.0-liter engine was already lighter than the 2.5-liter engine. Generally, that's not possible if the base was already "very good" . Sincerely

Yes, absolutely! But that's a nice piece of information, thank you! The valve timing is definitely not the only thing that wasn't quite thought through. However good the intentions may have been.


Best regards, Marcus.

Albrecht wrote:

You are forgetting about the vehicle weight in all of this.

You're right about the BUK, which was only available on the Ibiza model. But not with the AXR, which was also available in the Golf IV Variant, and it's not that much lighter than an A4 B5.

What's with all the complaining about insufficient power? This engine replaced the AEL 5-cylinder with 140 hp and constant smoke in 1998. It produced fewer emissions, had a better torque curve, more peak power, less weight, a good running culture thanks to the 6-cylinder and balance shaft, and also offered the option of increased power thanks to the 4-valve design. It was already quite good back then. It was not yet known that the engine had problems in every area.
The AKE had the highest power density per unit of displacement at the time. Nowadays, you only need 2 liters of fuel to get 180 horsepower.

christians wrote:

and in addition, the option for performance enhancement thanks to 4V.

But the VP44 completely disregarded that.
Regarding technical highlights, I really like this engine as well. However, in terms of durability and driving dynamics, I believe the AEL was significantly better.

christians wrote:

The AKE had the highest power density per displacement at that time.

2.2 horsepower per liter more than an AFN, which only has 8 valves and a VTG turbocharger. Hm...


But you're right, we're completely going off-topic again. Everyone should form their own opinion about the engine. There's definitely a lot of engineering involved, but what it has actually achieved is another matter...

Hello,

Octavia_4x4 wrote:

Just a question out of curiosity: How well does the 2.5 actually run, if the rocker arms have been ejected? Normally, it should then have the running characteristics of a bag of nuts...

I've also wondered about that. Then I read something about "21 remaining rocker arms" and sharply combined that it must be a 4-valve engine. So, unless, by some chance, 2 intake or exhaust rocker arms from the same cylinder are broken, the other valve will still allow enough airflow. You won't hear it at idle because the slightly reduced flow won't become noticeable until the higher RPM range. In that case, one of the engines might be lacking some power, but with 6 cylinders, there's still plenty of capacity left.

Best regards, Uli.

TDI-GTI-4-Motion wrote:

2.2 horsepower per liter more than an AFN, which only has 8 valves and a VTG turbocharger. Hm...

AFN 110 hp/1.9L = 57.9 hp/L
AKE 180 hp / 2.5 l = 72 hp/l

christians wrote:

TDI-GTI-4-Motion wrote: 2.2 horsepower per liter more than an AFN, which only has 8 valves and a VTG turbocharger. Hm... AFN 110 hp/1.9L = 57.9 hp/L AKE 180PS/2.5l = 72PS/L

Sorry, I was referring to the AKN. Of course, that might not be the case with the AKE. However, we also talked about this when the engine was removed, and there wasn't an AKE immediately available then.
And if we consider the AKE, we can compare it to the ARL, which was released 3 months later and had a power output of 78.9 PS/L.


But, you are naturally right, the V6 TDI engines were, when they were first released, the most powerful in terms of power output per liter, but only for a relatively short time.

For reasons I won't go into, I'm bringing this thread back up.

Specifically, I recently bought a "donor car" Passat (later referred to as the new one) that is largely identical to mine (according to the vehicle identification number, it was the 17th car produced after mine!).
Anyway, I've decided to fix up the replacement car and use the other one as a parts donor. First, an inspection of the camshafts was necessary.

Assuming that the two vehicles were likely manufactured on the same day, the quality of the components used would probably have been identical as well. And indeed, it was revealed that the camshafts in the new Passat showed similar signs of wear as in the other vehicle, and some rocker arms were also missing.


But: And now it gets interesting. The reason for the failure is completely different. Because in the new one, the slide rails are not worn down as severely as they were in the old one (approximately 50% less). They shouldn't have been eliminated yet!

However, many of the hydraulic components in this engine are damaged. You can clearly see how much wear and tear they have suffered. It's truly incredible. The failure rate is almost 50%! In the other engine, it was completely different. Those defects did not occur there. However, the connecting rods there were worn out.


The mileage of the two vehicles is relatively similar (240,000 km to 215,000 km). Then I looked at the service records of both vehicles and checked for oil changes and other maintenance. It appears that these services were always performed. In the case of the old Passat with the faulty rocker arms, the first change involved switching to regular 5W-40 oil.
In the case of the new Passat vehicles with the defective hydraulic lifters, 5W-30 Longlife oil was used until the end.

Whether this is related, I am not going to judge. But it might be some useful information for some people here...
In my opinion, it seems like they are facing a problem there, and they definitely can't handle the oil.


Best regards, Marcus.