Why are PDs so "slow" at the top?

Hello,

It's often said that turbocharged PD engines run out of air above approximately 3000 rpm, but this can be easily remedied with simple tuning (even just with a tuning box, without directly increasing boost pressure), and without producing excessive smoke, unlike VP engines.

Why is that the case, or why didn't VAG design the engines to be more rev-happy from the factory?
For example, is it possible to increase the power from 96 kW with 310 Nm of torque to 110 kW?

Are these just political reasons related to product strategy, or is there something concrete and technical behind it ?

ulf wrote:

...For example, is the power being increased from 96 kW with 310 Nm to 110 kW? Are these just political reasons related to product strategy, or is there something concrete and technical behind it

?

There is a 110 kW engine with 320 Nm of torque. Why should they build one with 310 Nm?

By the way, the 110 is running very happily in the higher RPM range.

Hello Ulf,

The 150PS PD engine is mechanically adapted to the higher power output, see [url][/url] under "VW News" and then "110kW P-Düse" (I can't "steal" the direct link). Among other things, the engine block and crankshaft are made of a stronger material.
It's probably somewhat subjective to say that the engines lack power at the top end, because they have such immense torque at low RPMs. The driver is likely encouraged to shift up a gear and then accelerate, rather than revving the lower gear excessively. Otherwise, these cars would probably be quite fuel-thirsty. A colleague has a Golf 4 with 115 horsepower, and he initially complained because the car consumed a liter more fuel than his old 3-series with a 1Z engine. He and his wife have already adjusted their driving style to the different engine characteristics, and now they are probably going to see a change in fuel consumption.

Best regards, Uli.http://www.tuneline.at{MARKER}

It is often said that naturally aspirated PD engines run out of air above approximately 3000 rpm.

'Humbug,' as Uli S. already said, the problem is that at lower speeds, there's more 'pulling' (likely referring to a sensation of strain or lag), while at higher speeds, the torque drops off or is limited, and the flow rate is reduced.

Hello Ulf,

I agree with my predecessors who say that this is subjective and is due to the enormous torque in the lower/mid RPM range.
When I switched to diesel and got my AFN "new" back then, I was also disappointed by the lack of power in the higher RPM range.
With PD motors, the torque amplification (maximum torque / torque at rated speed) is even greater.

Best regards,
Albrecht.

As a driver of a 96kW PD engine, I also have to say that it's subjective. The significant torque at low RPM leads to that assumption! What do you need that for in the higher RPM range? City and rural driving mostly happen in the RPM range where torque is most advantageous. Then there's the highway. And there, my car can easily reach around 180 km/h according to the speedometer. It gets a bit slower after that. That's true. But as a cruising speed, I find speeds up to 180 km/h more comfortable than, say, 200 km/h. Also, as I mentioned before, the PD engine starts to 'consume' a lot of fuel at that point!

Hi Ulf,

Okay, I drive a 2003 Octavia Combi with 96 kW, and I have to say that for such a 'tuned tractor engine,' it's surprisingly responsive.
The torque of 310 Nm is already achieved at 1800 rpm and remains above 290 Nm until approximately 3200 to 3300 rpm.
So, I'm not sure what you mean by 'taking the air out of the top.'

I think it's probably because the torque surge kicks in very abruptly.
I mean it's a 1.9-liter engine that produces 310 Nm of torque.
For larger, more powerful engines, the boost onset is somewhat more gradual because the difference in torque between 1400 rpm and 1800 rpm is not as significant – although it is very significant in a 1.9L TDI engine from VAG.
The V6-TDI doesn't have significantly more torque, but the torque curve is smoother due to the larger displacement. This is because it delivers more torque even at 1400 rpm, which is almost inherent to its design.
In short: The transition between having too little and having more than enough torque is, due to the design, within a very narrow speed range.

Mine runs up to about 210 km/h without me noticing that the pulling force is decreasing.
If you conduct field measurements, you should generally experience similar results.

Sure, here is the translation of the text from German to English:

'cu smith2'

Hello,

It's often said that turbocharged PD engines run out of air above approximately 3000 rpm, but this can be easily remedied with simple tuning (even just with a tuning box, without directly increasing boost pressure), and without producing excessive smoke, unlike VP engines.

Why is that the case, or why didn't VAG design the engines to be more rev-happy from the factory?
For example, is it possible to increase the power from 96 kW with 310 Nm of torque to 110 kW?

Are these just political reasons related to product strategy, or is there something concrete and technical behind it ?


Because they might then be able to completely destroy their V6 engines! (And they could actually do that anyway.)

I have an A4 with 96 kW, which has amazing torque at low RPM, but when overtaking on country roads, it could definitely benefit from a bit more power at higher RPM.
(An A4 Avant also weighs almost 1600kg ).
Okay, so I installed the *** chip, and wow, the engine is much smoother now and runs like a dream.
The torque comes on much earlier, is smoother and more refined compared to the standard version. It's almost as if the engine has been detuned rather than tuned, and at higher RPMs, the engine revs much more freely.
I don't want to know what it must be like in a small Seat or similar car.

Hello,

It's often said that turbocharged PD engines run out of air above approximately 3000 rpm, but this can be easily remedied with simple tuning (even just with a tuning box, without directly increasing boost pressure), and without producing excessive smoke, unlike VP engines.

Why is that the case, or why didn't VAG design the engines to be more rev-happy from the factory?
For example, is it possible to increase the power from 96 kW with 310 Nm of torque to 110 kW?

Are these just political reasons related to product strategy, or is there something concrete and technical behind it ?

Hello Ulf,

I think leolotus is right.

I drive a Passat Variant 3B PD, originally with 85 kW, and I've had it for about 90,000 kilometers.
According to my information, this model was the original PD model.

Since I was generally dissatisfied with the performance from the beginning, I kept digging and investigating.
Conclusion: Some PD models with 85 kW are incredibly fast, while others are barely powerful enough to spread butter on bread.

Here's one thing to keep in mind:
In my opinion, this is due to 'model blending'.
Okay, bitte gib mir den deutschen Text, den du übersetzt haben möchtest. 'It's a new model with an older control unit, so I think a lot of compromises were made.'

Our Passat was manufactured in June 1999, but is a 2000 model.
-old engine control unit!!, detuned performance (it must produce less than 96 kW!)
Older PD models run like crazy; they may have had [something]. Other LMM - Control.

After countless attempts, I had a conversation with a tuner who primarily distributes this OBD software solution through various channels. Car dealerships: There are countless log files for potentially identical models.
In my opinion, this is the cheapest way to sell used, de-stroked PD engines.
The torque curves are simply being cut off.

The only thing that helped was correcting the altered VW software.

Everything else is just garbage.

Meanwhile, I'm reasonably satisfied with my OBD tuning.

The car is supposed to have 110 kW and approximately 360 Nm of torque.
While I doubt that, the torque curve is quite smooth up to about 195, after which it becomes rather sluggish until about 205.

Slightly increased fuel consumption of the engine after refueling: approximately 0.5 liters.
Country roads are less common. Expert opinions can be created for an additional fee, even after the fact.
Average consumption: 7-7.5 liters per 100 kilometers, for long distances between 120-180 km/h.

Conclusion:
The facts completely contradict each other.
More power without increased consumption, while still meeting emission standards, results in =
Customer manipulation. (Sorry, I just had to get that off my chest.)

So long

Regards,
Thorsten.

ulf wrote:

Hello, It's often said that turbocharged PD engines run out of air above approximately 3000 rpm, but this can be easily remedied with simple tuning (even just with a tuning box, without directly increasing boost pressure), and without producing excessive smoke, unlike VP engines. Why is that the case, or why didn't VAG design the engines to be more rev-happy from the factory? For example, is it possible to increase the power from 96 kW with 310 Nm of torque to 110 kW? Are these just political reasons related to product strategy, or is there something concrete and technical behind it

?

That's misleading. You can see that in the driving schedule shown here.
Okay, I'm ready. Please provide the German text you want me to translate.

The impression that nothing more can be achieved above 3000 RPM is often described in the highest gear. The driving diagram above clearly shows how higher power, especially at the limit, affects acceleration. The differences can be as much as 50% at speeds around 190 km/h. More power doesn't necessarily mean more driving pleasure.
At least in my 96kW Golf, I don't experience a lack of responsiveness, even though I rarely rev the engine above 3000 RPM. It becomes particularly noticeable in the third or fourth gear...

Furthermore, the power curve in turbodiesel engines is relatively flat. This results in a significant amount of power in the lower RPM range, but the increase in power with increasing RPM is relatively small, which creates the subjective impression that the engine loses power at higher RPMs.
The R32 also has a maximum torque of 320 Nm, but only up to 250 horsepower. I wouldn't mess with that.

Hi Ulf,

"I'm not entirely happy with the torque curve of the automatic transmission, but you get used to it pretty quickly. In everyday driving, I never need to go above 3000 rpm, because if you shift early and take advantage of the boost, you'll quickly be in 6th gear." He usually drives at around 140-150 km/h, and that's where he stops being economical.

Probably, the PDs would break down even faster at high speeds if it were so much fun.

Okay, enough joking around. I've also driven the 96kW Golf a few times. And compared to the VP TDI, the torque delivery just feels unbalanced. It's probably because the lift is so strong at the bottom.
And the consumption really increases significantly at high speeds. I can't say that about my current employer right now.

Golfmann wrote:

Probably, the PDs would break down even faster at high speeds if it were so much fun.

Hi,

I had also seriously considered something along those lines, namely a kind of psychological lifespan extension for the engine or the timing belt.

The latter must transmit the sudden power surges required to generate the extremely high injection pressures.
And as the speed increases, so does the stress on the material, not only due to the inertial masses, but also due to the generation of the injection pressures.

If the engine is programmed to limit its power output, the average driver will avoid high RPMs and tend to drive in a higher gear, because it's not really worth pushing the engine hard with high RPMs.

Or am I fundamentally wrong in this assumption?

Hmm, maybe only half of it fits here: (Unfortunately, my topic was closed!)

My AJM engine always gave a significant jolt in the back at 1950 RPM, and above 3000 RPM, it visually felt like it was performing somewhat worse.

My ARL engine runs much more smoothly without that 'jerky' feeling, and you can also feel that the 150 horsepower starts to be enjoyable above 2600 RPM.
It's significantly better in the upper range!

All in all, I am finally satisfied with my Golf, but I haven't seen fuel consumption figures below 8.5 liters yet...
However, I haven't been able to ride a distance longer than 20km in the last 3 days, and things are always very busy in the winter.
But there's still a proper driving report coming!

Hello Ulf,

The power output of the PD elements is certainly not the limiting factor. As far as I know, the 150 hp PD model does not have any other type of belt drive. Instead, the modifications required to increase strength are becoming increasingly complex and expensive (e.g., crankshaft, connecting rods, pistons, large intercooler, turbocharger, etc.).
This is not desired for a basic, cost-effective engine (130 hp).
The 150 PD-PD engine represents a top-of-the-line configuration in a limited number of models, where the focus is likely less on cost and more on brand image.
At high speeds and loads, the exhaust gas temperature is usually the limiting factor. You can't use fuel to cool a diesel engine.

Best regards,
Albrecht.

Hello,

Albrecht wrote:

At high speeds and loads, the exhaust gas temperature is usually the limiting factor. You can't use fuel to cool a diesel engine.

With gasoline engines, even with a very rich fuel mixture, the exhaust gas temperature is significantly higher than with even the most powerful diesel engines. Even at full load and rated speed, gasoline engines operate with a Lambda value of approximately 1.4, meaning a 40% excess of air. This results in relatively cool exhaust gases. That's also the main reason why there aren't any VTG loaders for gasoline engines yet; they wouldn't work with them.

Best regards, Uli.