How accurate is calculated torque likely to be?

[pannetron]

I assume that the ECU calculates torque based on reported airflow and ignition advance using the virtual torque tables. How accurate is that likely to be? Seems it would be completely dependent on the virtual torque table values, which I'm sure I don't fully grok.
2025-06-10_09-46-49.jpg

[Cringer]

I assume that the ECU calculates torque based on reported airflow and ignition advance using the virtual torque tables. How accurate is that likely to be? Seems it would be completely dependent on the virtual torque table values, which I'm sure I don't fully grok.
2025-06-10_09-46-49.jpg

Virtual Torque is like Virtual VE (a mathematical estimation) of reality. It is accurate enough for what GM needs is to do on a factory engine to control the transmission and what not. I would not use it to replace a dyno. The ECM's reported Torque comes from Virtual Torque (there are also modifiers that are applied to the Virtual Torque tables).

[verlon]

GMW8762 states:

4.2.3.127.1 Powertrain Interface Definition. Engine Torque Actual Extended Range is transmitted by the
ECM. This signal provides information about the actual engine torque at the crankshaft. The basis of torque
calculation is characteristic maps within the ECM calibration set. The content of the maps is measured at an
engine dynamometer. The basic engine friction is considered as a function of cooling temperature, oil
temperature, engine speed and load. This includes the torque losses of water and oil pump and the variable
portion of A/C compressor torque losses (every component that is connected at an engine dynamometer, i.e.,
the content of a base engine). Variable torque losses of the generator (depending on the electrical load) and
the hydraulic power steering torque losses may be only partially included. Therefore the actual torque signal
does not fully represent the effective torque at the clutch.
Engine Torque Actual Extended Range Validity shall be set to ?Invalid? if the inputs for determining the data
value is failed or unavailable with the appropriate DTC set, and a backup value exceeds the accuracy
requirements.
Data Delay: 30 ms
Accuracy Requirement (Steady State):

Absolute Value (Engine Torque Actual Extended Range) > 50 Nm: +- 10%
Absolute Value (Engine Torque Actual Extended Range) <= 50 Nm: +- 5 Nm

But it has nothing in common with reality.
For example, completely stock L94 shows actual torque ~54 Nm in park/neutral
Commercial trucks/vans (with 5.3 and 6.0) and Corvettes usually has more accurate engine torque calculation.

[87gtNOS]

I assume that the ECU calculates torque based on reported airflow and ignition advance using the virtual torque tables. How accurate is that likely to be? Seems it would be completely dependent on the virtual torque table values, which I'm sure I don't fully grok.
2025-06-10_09-46-49.jpg

I set up the scanner to read torque and calculate HP and I use that as part of my street tuning. As an example, for WOT 2nd gear and 3rd gear runs, (streets of Mexico), I was adding fuel until the HP started to drop off and the area under the curve (BOTH the HP and TQ curves) became less...then I knew where the car was happy, not just relying on a magical 0.84 lambda # type thing....

[87gtNOS]

This is a run from 2000 rpm to 6400 rpm....the gray line is TQ and the Yellow is HP. They cross at 5252, about 391/391. Peak HP was 428 I think and the TQ was over 400 from 4000rpm +.

SO not only watching all the other things going on (Lambda, MAP, PE, etc) this helps see when you start to go backwards.

hp .jpg

[Cringer]

I set up the scanner to read torque and calculate HP and I use that as part of my street tuning. As an example, for WOT 2nd gear and 3rd gear runs, (streets of Mexico), I was adding fuel until the HP started to drop off and the area under the curve (BOTH the HP and TQ curves) became less...then I knew where the car was happy, not just relying on a magical 0.84 lambda # type thing....

That's not really going to be accurate or a good way to go about it. Virtual Torque takes into account the commanded EQ ratio. Simply changing lambda changes the calculated result and unless you have calibrated the Virtual Torque on a dyno, this outcome is useless IMHO. Also, unless you do back to back pulls, the weather is going to be a huge factor in the calculated cylinder airmass, which will really skew your results. You are much better off calculating acceleration or using some time based method to determine the work being performed.

EQ TQ.jpg

[Alvin]

There are post all over the gen 5 section where people are trying to get calc torque back in line after mods. That should tell you right there it isn't a reliable source.

[07GTS]

just use this ([8001.113.avg(-200)]) - ([8001.113.avg(200)])

its front wheel speed against future front wheel speed in time, it will show u if ur forward momentum is increasing or decreasing, then if u make power mods u can see if vehicle is faster or not, just note that it uses future data so will not work live in the scanner u have to save log and look back at it