FSI vs. TDI: Which Engine is More Powerful?

Hello.

In the "Gute Fahrt" magazine, issue 1/05, there is a comparison test of the Golf 5, specifically between the 140 hp TDI (2.0l) and the 150 hp FSI (also 2.0l, if I remember correctly).

I only read it briefly, but it definitely states that the FSI, with a maximum of 200 Nm of torque, performs better in most acceleration tests compared to the TDI with 320 Nm of torque.

Two speed ranges (60-100 and 80-120?) were tested, each in gears 4 through 6.
Only in 4th gear was the TDI somewhat better, while in 5th and 6th gear, the FSI was noticeably faster.

This completely turns the well-known TDI (diesel) vs. gasoline relationship on its head, especially since the previous FSI engines were generally considered to have even less torque than regular gasoline engines.
The latter completely aligns with my experiences in a Mitsubishi GDI (a competitor to FSI): Either you drive in a high gear and save fuel, but without any noticeable response when you press the accelerator, or you downshift and accelerate using the engine's rev range (the illusion of saving fuel remains, because the fuel consumption display cannot be switched to the instantaneous value ).


Unfortunately, I don't have that specific publication, but perhaps someone here knows something about the technical background?

Are the 2.0 TDI engines less responsive at low RPM compared to the 1.9 PD engines, meaning that "nothing" happens below 1900 rpm? And/or, is the FSI engine geared so short that it can compensate for the TDI's lack of low-end power?

Or could a faulty TDI engine (e.g., with incorrectly adjusted maximum boost pressure of the variable turbine geometry) have slipped through the testing process?

Are the 2.0 TDI engines less responsive at low RPM compared to the 1.9 PD engines, so that 'nothing' happens below 1900 rpm, and/or is the FSI engine so short-geared that it allows the TDI engine to be overtaken

I also read the test, and I think that the combination of lower weight (correctly, mass) and shorter gearing gives the FSI an advantage in this case.

You should check the GF forum to see if anyone has translations available; there are always people there who can quickly provide them. The GF test doesn't offer anything on that topic.

Cheers.
Michael.

P.S. If you're interested, I can scan the test and send it to you.

ulf wrote:

... I only read it briefly, but it definitely states that the FSI, with a maximum of 200 Nm of torque, performs better in most acceleration tests compared to the TDI with 320 Nm of torque. ... Are the 2.0 TDI engines less responsive at low RPM compared to the 1.9 PD engines, meaning that "nothing" happens below 1900 rpm? And/or, is the FSI engine geared so short that it can compensate for the TDI's lack of low-end power? Or should a defective TDI (e.g., with incorrectly adjusted maximum boost pressure of the VTG) have somehow slipped through the testing process?

Based solely on the provided information, it would essentially become clear that the translations are not comparable (which, in my opinion, is a weakness of the entire benchmarking process).

"Based on my own experience with a Golf 4 130PS TDI and a Golf 5 140PS TDI, the 140PS version feels noticeably less powerful in the lower RPM range, which shouldn't be the case according to the data (torque curve). On the other hand, if the torque is specified as 320Nm, but the engine builds up that torque more slowly for comfort/emissions reasons, it will also lack pulling power. The common torque curves show the maximum torque at a certain RPM, but not over time."
So, if an older 1.9 engine takes 2 seconds to reach 310 Nm of torque, and a 2.0 engine takes 4 seconds to reach 320 Nm, which one is faster (numbers are hypothetical)?

*Speculations about the space-time continuum.*

Given that they are very close in terms of top speed (FSI 209 vs. TDI 205), with the FSI reaching its 150 horsepower at 6000 rpm, essentially at the "last moment," and the TDI delivering its 140 horsepower to the crankshaft at 4000 rpm, and also considering that the maximum torque for both engines occurs at double the rpm (FSI 3500 rpm, TDI 1750 rpm), I suspect that the FSI has a much shorter gear ratio, while the TDI has a longer one.
Unfortunately, I haven't been able to find the exact translations anywhere. "Gute Fahrt" only states the following about it:

The reason for the FSI's better performance is clearly its significantly shorter transmission, as well as the delayed build-up of turbocharger pressure in the TDI.
Source: Gute Fahrt 1/2005.

mhh Weight according to Volkswagen's website: FSI 1242kg - 1392kg, TDI 1281kg - 1451kg.
Okay, I think a difference of at least 39kg is simply not worth mentioning. I'm just curious why the difference in the maximum weights is 57kg. What extra features does the TDI offer that account for the 18kg difference? Is the heated seat offered as an option on both models? Does it include a large generator and a huge battery?

Especially because the FSI engine is only available starting with the Comfortline trim level, and the TDI engine is also offered as a Trendline.

@Strich8
Please contact the homeowner beforehand if you want to publish something whose copyright is definitely not yours. Just a little tip! Although it's certainly interesting.

joegolf wrote:

Based solely on the information provided, it should become clear that the translations are not comparable (IMHO, this is a weakness of the entire testing process).

It's complicated... Nevertheless, the characteristic Nm peak typical of TDI engines has, despite the disadvantage in gearing and weight, consistently been sufficient to outperform comparable gasoline engines.

Quote:

So, if an older 1.9 engine takes 2 seconds to reach 310 Nm, and a 2.0 engine takes 4 seconds to reach 320 Nm, which one is faster (numbers are hypothetical...) *let's put some guesses out there*

That would be a whole new level of exhaust system modification – something I wouldn't have a hard time believing.

matthias wrote:

The FSI engine produces its 150 horsepower at 6000 rpm, which is achieved in the "last moment," while the TDI engine delivers its 140 horsepower to the crankshaft at 4000 rpm. Also, in both the FSI and TDI engines, the maximum torque is reached at double the engine speed (FSI 3500 rpm, TDI 1750 rpm)

.
...which even makes the TDI seem more appealing, based on this shaky foundation of numbers, in terms of its responsiveness.
If we define the usable speed range as the rpm ratio between the Nm peak and the Pmax (maximum power), then the FSI engine has a range of 1.71, while the TDI engine has a range of 2.28.
According to this, the "normalized" TDI speed range would be 33% wider than that of the FSI .

However, the FSI engine is likely to experience a less significant drop in power below 3500 rpm compared to the TDI engine below 1750 rpm, which somewhat relativizes this observation.

Strich8 wrote:

You should check the GF forum to see if anyone has translations available; there are always people there who can quickly provide them. The GF test doesn't offer anything on that topic.

Hi,

I already answered you there, but here it is again:

Motor: I/II/III/IV/V/VI/R = Reverse / A = Axle.

2.0 FSI (150 hp): 3.78/2.27/1.52/1.19/0.97/0.82/R3.6/A3.65

2.0 TDI 16V (140 hp): 3.77/2.09/1.32/0.98/0.78/0.65/R3.64/A3.45

"Consequently," or "Therefore," or "It follows that..."

The 6th gear in the TDI has a ratio of 1.335, while the 5th gear has a ratio of 1.315.
The 4th gear has a gear ratio that is 1.285 times longer than the FSI.

Best regards,
Munch.

Okay, thank you as well, Mampf. So, the theory is now watertight.

Mampf wrote:

Motor: I/II/III/IV/V/VI/R = Reverse / A = Axle. 2.0 FSI (150 hp): 3.78/2.27/1.52/1.19/0.97/0.82/R3.6/A3.65 2.0 TDI 16V (140 hp): 3.77/2.09/1.32/0.98/0.78/0.65/R3.64/A3.45

It's surprising that these 6-speed transmissions no longer have a dual-axis design (like in the 1.9 TDI generation).

Now, we would also need the tire sizes and torque curves for both engines, and then we could use a vehicle dynamics simulation tool to generate acceleration curves.

However, based on the currently known peak values for Nm (torque), Nm (maximum torque), and their respective RPM (revolutions per minute), it is my opinion that we can also make reasonably well-informed assumptions, following the example of other engines.

I'll give it a try and post the results online.

ulf wrote:

It's surprising that these 6-speed transmissions no longer have a dual-axis design (like in the 1.9 TDI generation). ...

"They were probably already included in the initial calculations. As far as I can remember, the "older" tests for the 1.9 engines often only provided "simple" gear ratios as specifications."

joegolf wrote:

ulf wrote: It's surprising that these 6-speed transmissions no longer have a dual-axis design (like in the 1.9 TDI generation). ... Probably, they were already included in the multiplication. As far as I can remember, the "old" tests for the 1.9 engines often only provided "simple" gear ratios.

Then we shouldn't specify any axle ratios at all, but Mampf wrote "1 axle" (instead of 2) as the last entry...

Okay, I've looked at the timetable again.
The input data consists of the transmission data provided above, a tire size of 195/65 R15 for each tire, the minimum weight plus 75 kg for the driver, and the assumed engine curves from the upper diagram in the attachment.

While I took the aerodynamic drag coefficient from the Polo 9N, even then it was more of an estimate than an exact measurement.
And ultimately, this is only about the airflow at speeds around 100 km/h, where air resistance doesn't really play a significant role yet.

The simulation shows the familiar, "perfect" TDI world of superior torque, meaning that the TDI can still keep up even when the FSI is accelerating in a lower gear.
In terms of performance, the TDI only slightly outperforms the FSI in 6th gear, specifically between 60 and 75 km/h.
-> So, the reasons for the test results remain a mystery... perhaps joegolf is right about the dynamically, brutally slow torque increase?

Please excuse the blurry image, but that's why it's only 100 KB in size. Hopefully, everyone can make out what's meant.

Does the 150 hp FSI engine not have a turbocharger, unlike the 200 hp engine in the Golf GTI?

I've also heard that FSI engines, as Ulf describes, are supposed to be "sluggish." This always referred to the older 1.6-liter engine with approximately 105 horsepower, which, unlike the non-FSI 1.6-liter gasoline engine, was apparently considered more "sluggish" and not necessarily more fuel-efficient.

Perhaps the newer 150 hp version has emerged somewhat from this shadow.

It would be interesting to compare the fuel consumption figures of diesel and FSI engines. If "FSI" is abbreviated so short, it probably won't go down well with the marketing department...

However, I have some doubts about the objectivity of the test. "Gute Fahrt" is, after all, a publication closely associated with Volkswagen, and they are likely eager to promote the FSI models, as they haven't been particularly successful so far. If, by chance, the floor mat was obstructing the gas pedal in the TDI test...

Holger247 wrote:

The 150 hp FSI doesn't have a turbo, unlike the 200 hp engine in the Golf GTI, right?

No. Otherwise, the torque would definitely not be limited to 200 Nm .

Quote:

However, I have some doubts about the objectivity of the test... they want to offer the FSI models, but they haven't been a huge success so far. If, by chance, the floor mat was covering the accelerator pedal in the TDI...