TDI Chiptuning: Legal +10 HP = Awesome!

Hello,

I just found a nice performance graph online that illustrates how legal horsepower "deception" works.
The measured 161 horsepower is adjusted based on the ambient temperature and air pressure (42°C / 979 mbar) to sea level and 20°C, where a naturally aspirated gasoline engine would apparently produce 171 horsepower according to standard correction factors.

What does the 9N-ASZ software tell us?
The torque limiter does not have an ambient pressure correction, and the full boost pressure is maintained down to an ambient pressure of 980 millibars.

With an air temperature of 42°C (in March - is the test bench located in some kind of sauna? Or are they measuring somewhere in the intake manifold?), the LLT (low-temperature combustion) will barely exceed 80°C during a few seconds of full load on the test bench, which is where the thermal protection measures start to take effect.

According to the test results, under standard (naturally aspirated) conditions, the tested TDI engine would not consume any more diesel fuel, would not generate any additional boost pressure, and therefore would not produce any more horsepower than the measured 161 hp.
A chip tuner who understands software will know this (or at least where to look for the information).

However, it is permissible to state a "nominal power" of 10 horsepower more in the diagram and to present one's own advertising for 170 horsepower as achieved, based on a standard that does not account for TDIs.

Assuming a typical, healthy naturally aspirated engine produces around 140 horsepower, the tuner has only added about 21 actual horsepower. However, on paper, they can proudly claim to have achieved nearly double that gain.
171 measured horsepower (DIN) minus 130 catalog horsepower equals a 41 horsepower tuning success!

The moral of the story?
The world wants to be fucked, and those who don't participate are only to blame .

"I know that there are differences in the measurements. There's a measurement according to the EC standard, which usually results in a higher value, but reputable tuners only measure according to DIN standards. In my own measurement, I would have had approximately 170 horsepower according to the EC standard, but 161 horsepower according to DIN. However, a friend of mine says that even production vehicles are sometimes measured using the EC standard."

Given the air temperature, they must have used a low-temperature limit (LLT) setting. At an ambient temperature of 42°C, I personally wouldn't even allow them to measure my car.

Hey Ulf,

I mentioned this somewhere else (a company in Ulm), and that was back in 2001, but it's a similar situation. However, the temperature there was okay, but all vehicles leaving through the gate had a tire pressure of 945 mBar recorded in the log.

Aron wrote:

I mentioned this somewhere else as well (a company in Ulm), but it was back in 2001, and the situation was similar. However, the temperature there was okay, but all

vehicles that left through the gate had a tire pressure of 945 mBar recorded in the log.
Hi Aron,

A company in Ulm... let me guess, they don't offer chip tuning} there?

Edit:
945 millibars is still the average atmospheric pressure at an altitude of 540 meters above sea level, and that corresponds roughly to the city of Ulm.
This results in a Pnorm correction factor of approximately 7% on the measurement result, which, as mentioned before (at least partially), does not have a real-world basis for TDIs.

ulf wrote:

A company in Ulm... let me guess, that there is no chip tuning offered there? Edit: 945 millibars is still the average atmospheric pressure at an altitude of 540 meters above sea level, and that corresponds roughly to the city of Ulm. This results in a Pnorm surcharge of approximately 7% on the measurement result, which, as mentioned with TDIs, does not have a real basis (at least partially).

Hi there,

Okay, the company name ends with "Motorsport"... I looked at it quite closely when I left. That day, according to wetter.com, the atmospheric pressure was supposed to be around 1000 hPa.

Currently, it's even over 1000 hPa. The conversion was a 1:1 ratio. Even if it might end up being around 5 paper kilowatt-hours in the end, it's still not nice.

Are the air pressures in the weather data adjusted for altitude in any way? Perhaps the pressure sensor on the test stand only measures in increments of 50 millibars.

Are there any other ways to mess around on the dyno?

Aron wrote:

Are the air pressures in the weather data adjusted for altitude in any way? Perhaps the pressure sensor on the test stand only measures in increments of 50 mbar.

Yes, the pressure values are converted to sea level by meteorologists (otherwise, weather maps would show perpetual low-pressure systems everywhere ).

The cars, on the other hand, have to cope with the thin air at high altitudes, so it is correct to measure using the local pressure. The test bench results are converted to sea level (and 20°C) according to DIN standards - even though this doesn't reflect reality for TDIs.

Quote:

Are there any more ways to mess around on the dyno?

There are many ways to do it. A relatively effective and inconspicuous method is to not disengage the clutch when rolling. This increases the calculated power by adding the losses of the engine being dragged along.
Gentle (gradual) braking works on the same principle.

Conversely, the calculated power can be slightly reduced if, instead of just disengaging the clutch when decelerating, you shift the transmission into a lower gear (e.g., as a preliminary measurement for chip tuners ).

BTW: I'd be interested to know what the approximate fake performance gain is between "rolling with a gear without disengaging the clutch" and "rolling in a low gear" without making any changes to the engine...

Hello Ulf,

The question of how pressure and temperature differences affect performance has always fascinated me! Based on my subjective experience, all my TDIs have always been able to deliver their full rated power (maximum speed), but the torque curve, especially during the hottest summer months, was somewhat lacking due to the turbidity characteristic (lack of intercooler effect?). Perhaps the lack of air density was also a crucial factor in achieving the maximum speed?


You write:

What does the 9N-ASZ software tell us?
The torque limiter does not have an ambient pressure correction, and the full boost pressure is maintained down to an ambient pressure of 980 millibars.


Where does the aircraft read the current QNH/QFE value from? I thought it always used a factor (approximately 1.3 bar for standard atmospheric conditions) above the actual ambient pressure.

Therefore, at an altitude of 2500 meters on the Großglockner road, the absolute pressure in the intake manifold should be approximately 2.0 bar, not 2.3 bar as would be the case at sea level.
Regarding that matter, the tuner who operates his workshop up there should be instructed to recalculate things, because otherwise he's only hurting himself.

Or are we talking past each other again?
Thank you for your reply.

Best regards,

ObenbeiMutti wrote:

Where does the aircraft query the current QNH/QFE from?

He's only querying the current outside air pressure (QFE) using a sensor in the Message Service Gateway (MSG).

Quote:

I thought it always exceeded the actual ambient pressure by a certain factor (in the case of ASZ, by 1.3 bar).

No, the LD target pressure values in the KF (calibration file) are absolute pressure values, just like those that come out during logging.
However, the maximum allowable load is limited by a protective control unit that uses external pressure (also as an absolute value, via the controller) and speed to determine the maximum allowable load setting.

Quote:

Therefore, on the Großglockner road at an altitude of 2500 meters, the absolute pressure in the intake manifold should be approximately 2.0 bar, and not 2.3 bar at sea level.

Yes, something like that.

Quote:

Regarding that matter, the tuner who operates his workshop up there would already be advised to recalculate, because otherwise he risks harming himself.

Generally correct. However, the power loss at high altitudes for TDIs doesn't follow the simple conversion factors used for naturally aspirated gasoline engines: as a result, TDIs (depending on the software! - as far as I understand) only start to lose power at altitudes of approximately 950 mbar or higher, whereas naturally aspirated gasoline engines already experience about a 6% power loss at that altitude.

Okay, I understand now. Thank you very much.

ulf wrote:

... But the power loss of TDIs does not generally follow the simple conversion factors used for naturally aspirated gasoline engines. ...

Therefore, proper testing stands also have tables for correction factors that depend on the vehicle. However, most technicians are too lazy to look them up.

Bertil wrote:

That's why proper testing stands also have tables for correction factors depending on the vehicle. However, most technicians are usually too lazy to look them up...

Ah, now I understand why some TDI protocols show only minimal differences between Pmot and Pnorm, even though the ambient pressure and temperature would actually allow for quite significant increases, similar to what is shown in the diagram above.

From what I've read recently, this situation with the testing stations is a risky game. Ideally, any potential errors might cancel each other out, but in the worst-case scenario, it could lead to a 'Kawenzmann error' (a significant and potentially damaging mistake).

However, it's probably fair to assume that tuner manufacturers have questionable motives, as the reputable automotive magazines consistently provide sufficiently plausible and accurate results for their long-reach antenna tests.

I still find it hard to believe that the ASZ (presumably a vehicle or engine) has a serial production variation of 7.8% to 10 horsepower. Manufacturers don't give things away or use bad references! The GPS-recorded maximum speeds seem to align well with the manufacturer's specifications, assuming the standard tires are used.

According to the GPS, mine is running exactly 1.0 km/h faster when the tires are fully inflated.

So, with 8 horsepower, the maximum speed difference across all sedans, regardless of fuel type, is a mere 5 km/h within the speed range starting from 220 km/h, when comparing the models. (163 hp ~ 225 km/h, 170 hp gasoline engine ~ 230 km/h.)

It's easy to make generalizations about all car manufacturers: modern sedans with 170 horsepower always seem to reach around 230 km/h, while those with 150 horsepower typically go up to around 220 km/h.

Does the K-Power or the good old DZR have any input on this?

To the best of my knowledge, there is a slightly more suitable metric that mechanical engineers often prefer to use in this context instead of torque: the tensile force margin.

I can't provide formulas, but as far as I understand, the argument against using 'torque' as a measure of acceleration perception is that the moving masses of the motor also create a 'dynamic resistance' to changes in rotational speed. Therefore, a motor with twice the inertia of another will accelerate worse at the same torque.

This would also have an impact because diesel engines require more robust connecting rods, crankshafts, etc., due to the higher combustion pressures, which further complicates comparisons between gasoline and diesel engines.


Perhaps the results are being artificially inflated if this is not taken into account. It would also nicely explain why some diesel vehicles are becoming more popular.

Mechanical engineer? Does anyone know anything about that?

I'd like to bring up another point, which is perhaps going in a different direction, but:

Someone who conducted AU training courses in this area (from Coburg) once shared an interesting observation.
The higher-powered engines, such as the M3, are often used for various examples and are frequently found on test benches.
The E90 must be the one. What do you think went through people's minds when they heard that news?
Due to the OBD2 requirement, a testing device must be connected for the emissions test. When the device is connected, the engine meets the Euro4 emission standard. However, if the device is disconnected, it no longer meets the Euro4 standard. Furthermore, when the engine is tested on a dynamometer with the device connected, the power output is 20 kW lower than expected. Without the device, the power output is correct.

I wasn't actually there, I only heard about it from the lecturer who conducts the AU training courses.
No, this isn't a belated April Fool's joke; I find it harsh how the manufacturers are proceeding with the bandages. Of course, it makes sense that the measurement cycle requires the OBD2 protocol, so they probably just solved the problem in that way.

ObenbeiMutti wrote:

I still don't want to believe that the ASZ has a serial production variation of 7.8% -> 10 horsepower. Nothing is given away or poorly referenced by the manufacturer! The GPS-logged maximum speeds simply match the factory specifications, assuming standard tires. My device shows a speed that is exactly 1.0 km/h faster according to the GPS, when the tires are overinflated.

You can usually disregard the maximum speed you might see on a flat surface in real-world conditions because even the slightest headwind or tailwind will directly affect the result. The same principle applies to very small inclines and declines.

My Polo's power output, according to the official DZR measurements taken at the factory, consistently fell between approximately 138 and 143 horsepower across numerous tests – and I meticulously checked all the input parameters: I measured the tire rolling circumference, had multiple weighings done, etc.

Search within this forum for information on power output variations, etc.: most posts from knowledgeable people confirm that TDIs, on average, exceed the legal tolerance of 5(?)% to a greater extent, and this is usually done in favor of the customers.

Quote:

Does the K-Power or the good old DZR actually work with it?

Of course, it doesn't measure the maximum speed, because the measurement principle is based on acceleration.

The E90 must be what it is, so what do you think went through people's minds when the information came out:
Due to the OBD2 requirement, the tester for the emissions test must be connected. When the tester is connected, the engine meets the Euro4 emission standard. If the tester is not connected, it no longer meets the Euro4 standard. Furthermore, when performing a power measurement with the tester connected on the dynamometer, 20 kW less power is measured than expected. Without the tester, the power reading is correct.

Hello Aron,

No, this definitely no longer exists!

Cycle detection used to exist, but it was quickly shut down and resulted in severe penalties.

A vehicle MUST always comply with the emission values of the emissions cycle. Therefore, it is not possible to 'disable' the EURO4 emission standards without modifying the approval certificate (ABE).
However, it should be noted that emissions are not measured above a speed of 120 km/h.

It's easy to make generalizations about all manufacturers, stating that modern sedans with 170 horsepower always go up to around 230 km/h, while those with 150 horsepower always reach approximately 220 km/h.

Unfortunately, it's not that simple, because the most important factor in determining a vehicle's top speed is its aerodynamic drag area. Aerodynamic drag changes exponentially.
The best example of this is the Lancia Delta HF Integrale EVO2: despite having 220 horsepower, the engine couldn't accelerate this mobile brick to over 215 km/h.
The T5 is another example.
However, the aerodynamic surfaces of modern cars are becoming increasingly similar.

Please search here in the forum for information on power output variations, etc.: most posts from knowledgeable people confirm that TDIs, on average, exceed the legal tolerance of 5(?) by a significant margin, and this is usually done to benefit customers.

'That's correct, however, it is also known that TDI engines lose excessive power over the course of their lifespan. Therefore, one might speculate that they initially release more power so that, at around 100,000 km, the specified standard power output is still present. '

Best regards, Jochen.

Hi Jochen,

Quote:

That is correct; however, it is also known that TDIs can lose excessive power over the course of their engine life.

Okay, I'm not noticing anything . Despite having 241,000 km. The Mass Air Flow (MAF) sensor problem, with too low readings and therefore constant operation in the soot reduction mode, seems to affect specific production years more than others. I certainly can't claim that all older TDIs suffer from this issue.

Performance loss is perhaps more likely to occur with the DPF devices, which tend to suffer from clogging as they age .
I've already had new 140hp 2.0 TDI engines with a DPF that performed significantly better than the specified 140hp and tolerance.

Best regards, Rainer.