Virtual Torque adjustments

[rbooth]

Can one of you experienced guys confirm my understanding of modifying the virtual torque.

Is the goal to input the actual torque of the engine at the user adjusted points or is it to match or closely match what the computer is calculating the predicted power to be at the same points?

Just seems like adjusting to actual delivered torque would also require a way to adjust predicted torque as well. But maybe I am missing something!

[Higgs Boson]

you want the model to match what the car actually makes, just like your airflow model.

[rbooth]

OK, thanks.

[meatbag]

Are you guys having better luck using estimated flywheel torque or actual measured torque?

[Higgs Boson]

Are you guys having better luck using estimated flywheel torque or actual measured torque?

desired MAP, desired airmass, desired airflow vs actual

[Redline MS]

Are you guys having better luck using estimated flywheel torque or actual measured torque?

GM uses air mass to calculate torque as they have a direct correlation. From there they know the frictional loss of the engine to determine BHP. If you can really nail your calibration the air mass should match the torque. Once this is been determined much falls into place. From there GM knows the torque multiplication from the trans input shaft to the axle which is why you see those values under TQ management. Getting the air model in line is not to hard but not having access to all the limit tables forces you to skew tables to stay under certain limts

[Jay@HAP]

GM uses air mass to calculate torque as they have a direct correlation. From there they know the frictional loss of the engine to determine BHP. If you can really nail your calibration the air mass should match the torque. Once this is been determined much falls into place. From there GM knows the torque multiplication from the trans input shaft to the axle which is why you see those values under TQ management. Getting the air model in line is not to hard but not having access to all the limit tables forces you to skew tables to stay under certain limts

If you get a chance can you explain how air mass relates to calculated torque and how it's calculated?

Thank you for any information.

[HeavyChevy305]

If you get a chance can you explain how air mass relates to calculated torque and how it's calculated?

Thank you for any information.

+1.

[dertobi]

as a rough estimation you can 1:1 convert airmass [g/s] to engine power [kW] and from there to torque via the rpm coherence of torque and power.

if you want to have it exactly, there will be the compressible gas equation and efficiencies involved . but as a rule by thumb the method above works very well.

[volcom8190]

anyone mind posting a histogram file of one of/both of the tables they are using. I think I have mine setup correctly, just getting some really strange percentage error values in some cells. Seeing upwards of 200+% on a basically stock truck in some regions

[Higgs Boson]

anyone mind posting a histogram file of one of/both of the tables they are using. I think I have mine setup correctly, just getting some really strange percentage error values in some cells. Seeing upwards of 200+% on a basically stock truck in some regions

look at your Throttle Desired values and see if they make sense. it's not your histogram. it's garbage in, garbage out, not the machine.

[Redline MS]

as a rough estimation you can 1:1 convert airmass [g/s] to engine power [kW] and from there to torque via the rpm coherence of torque and power.

if you want to have it exactly, there will be the compressible gas equation and efficiencies involved . but as a rule by thumb the method above works very well.

Its close enough for this discussion although there are numerous other "trim" factors that will skew the final numbers. Also note that the "torque" valve GM uses is "Brake Torque" at the crankshaft

[mbray01]

Up to 2014 was flywheel torque modeling. 2015+ is axle torque. The torque modeling went from looking at how the engine sees torque, to now looking at how the whole car sees torque

[Higgs Boson]

Up to 2014 was flywheel torque modeling. 2015+ is axle torque. The torque modeling went from looking at how the engine sees torque, to now looking at how the whole car sees torque

its crank hp in the Virtual Torque Editor even though Driver Demand uses axle torque. BTW, I think it's the A8 that uses axle torque rather than the model year. The sticks I have seen still use crank hp in the DD table.

[mbray01]

Hmmm, I guess i haven't really paid that much attention to whats really being outputted. Just going off of the massive amounts of gm literature I have read concerning this when we were trying to crack the torque modeling coefficients when we started seeing this stuff in 2013, and 2014

[schpenxel]

mmmm GM literature, mind sharing?

[Higgs Boson]

Hmmm, I guess i haven't really paid that much attention to whats really being outputted. Just going off of the massive amounts of gm literature I have read concerning this when we were trying to crack the torque modeling coefficients when we started seeing this stuff in 2013, and 2014

A8 came out in 2015. :-)

[mbray01]

my2015, but in 2014

[Higgs Boson]

yes. i only talk in model years I'm in the car business, lol!

[GrannySShifting]

desired MAP, desired airmass, desired airflow vs actual

I logged this, Throttle Desired MAP, Airmass, and Airflow all read 0 at WOT - the only thing that does show is Throttle Desired Area Final going to 100%