Need Help Interpreting Dyno Results on 5.3 with 6L80

flyingfool · November 17, 2019

7 hours ago, davester said:

Um, that's not a "dyno run". That's just speeding on a public road.

There's no sensor in your truck that measure how much torque and/or horsepower it is generating, anywhere in the drivetrain. Any numbers your app is showing to you are just a rough approximation of what power your truck should be generating, if everything is working properly, likely under ideal circumstances.

its actually more accurate than a dyno, because your adding more real world variables , like drag from wind resistance, and drag on all four tires , and better cooling at speed.

I'm not a 20 year old punk speeding recklessly, I find deserted roads that are very safe to do this on.. SUnday morning 5 am no one is around.

au contraire ... there are sensors that are fully capable of calculating all this information, the TCM relies heavily on torque management to shift and protect the transmission. and hp is easily given with g-meter, rpm, etc....

Edited November 17, 2019 by flyingfool

truckguy82 · November 17, 2019

1 hour ago, flyingfool said:

its actually more accurate than a dyno, because your adding more real world variables , like drag from wind resistance, and drag on all four tires , and better cooling at speed.

I'm not a 20 year old punk speeding recklessly, I find deserted roads that are very safe to do this on.. SUnday morning 5 am no one is around.

au contraire ... there are sensors that are fully capable of calculating all this information, the TCM relies heavily on torque management to shift and protect the transmission. and hp is easily given with g-meter, rpm, etc....

The goal of the dyno is to know your horsepower

Wind drag from the vehicle is the exact opposite of the sort of variable you want to introduce to get that number.

Those are variables you want for tuning the vehicle, but certainly not for the purpose of figuring out how much horsepower you have

Edited November 17, 2019 by truckguy82

flyingfool · November 17, 2019

HP is HP regardless of wind drag, i dont see where a street simulated dyno run vs a chassis dyno matters.... sound like you want an engine dyno if you really want to cut out the chassis and tranny variables. ..

davester · November 17, 2019

5 hours ago, flyingfool said:

its actually more accurate than a dyno, because your adding more real world variables , like drag from wind resistance, and drag on all four tires , and better cooling at speed.

I'm not a 20 year old punk speeding recklessly, I find deserted roads that are very safe to do this on.. SUnday morning 5 am no one is around.

au contraire ... there are sensors that are fully capable of calculating all this information, the TCM relies heavily on torque management to shift and protect the transmission. and hp is easily given with g-meter, rpm, etc....

There COULD be a sensor on your truck to find it out, but there isn't. Instead, GM has some tables indicating how much power the engine it thinks the engine makes under various conditions, and uses that value. So, whatever hp and/or torque you see displayed is not based on what hp/torque the engine is actually putting out, just what the ecm thinks it should be putting out, based on a calculation.

A dyno run is something that actually measures what hp/torque something is putting out.

flyingfool · November 17, 2019

all the numerical data, being created by the engine and its sensors, all fall neatly into the Physics formulas for calculating Horsepower and Torque. the ecus have this stuff programmed into the software.. do you disagree?

list off all sensors and plug in the data into the formula for HP or Tq..and if your missing the Torque number solve for the unknown you just solve for it using physics formulas..

all of which is happening within half a second. atleast from the OBD2 port, , but internally in the ecu I bet its much faster calculation.

truckguy82 · November 17, 2019

11 minutes ago, flyingfool said:

all the numerical data, being created by the engine and its sensors, all fall neatly into the Physics formulas for calculating Horsepower and Torque. the ecus have this stuff programmed into the software.. do you disagree?

list off all sensors and plug in the data into the formula for HP or Tq..and if your missing the Torque number solve for the unknown you just solve for it using physics formulas..

all of which is happening within half a second. atleast from the OBD2 port, , but internally in the ecu I bet its much faster calculation.

Yes I do disagree. I know all the sensors. They have all been pretty much the same since 1996.

You could possibly get to an extremely rough calculation by using the maf, map, afr, and fuel flow.

All this sensor data can basically tell you how much air is going in and how much fuel your burning with the air. Basically it knows how powerful the explosions are.

Would this information be accurate if you have a completely stock vehicle and you know, say the exhaust back pressure? Yeah it could theoretically be close. As soon as you change anything, this all becomes irrelevant. Put a restriction in your tailpipe, none of your sensors will tell you it’s there yet it would make way less power. Disconnect all your accessories drives in the engine bay, your sensor data won’t know that.

So yeah, algorithms based off sensor data is nearly worthless unless it’s a bone stock vehicle that the algorithm is still applicable.

davester · November 17, 2019

21 minutes ago, flyingfool said:

all the numerical data, being created by the engine and its sensors, all fall neatly into the Physics formulas for calculating Horsepower and Torque. the ecus have this stuff programmed into the software.. do you disagree?

list off all sensors and plug in the data into the formula for HP or Tq..and if your missing the Torque number solve for the unknown you just solve for it using physics formulas..

all of which is happening within half a second. atleast from the OBD2 port, , but internally in the ecu I bet its much faster calculation.

Well, you are confusing theory with actual. If you are happy with an approximation, great. Some people want an actual measurement.

flyingfool · November 18, 2019

18 hours ago, truckguy82 said:

Yes I do disagree. I know all the sensors. They have all been pretty much the same since 1996.

You could possibly get to an extremely rough calculation by using the maf, map, afr, and fuel flow.

All this sensor data can basically tell you how much air is going in and how much fuel your burning with the air. Basically it knows how powerful the explosions are.

Would this information be accurate if you have a completely stock vehicle and you know, say the exhaust back pressure? Yeah it could theoretically be close. As soon as you change anything, this all becomes irrelevant. Put a restriction in your tailpipe, none of your sensors will tell you it’s there yet it would make way less power. Disconnect all your accessories drives in the engine bay, your sensor data won’t know that.

So yeah, algorithms based off sensor data is nearly worthless unless it’s a bone stock vehicle that the algorithm is still applicable.

you forget about the 3 axis Accelerometer sensor which plays a bit part in calculating power. g-tech and 1/4 mile track testing are very close on HP data

truckguy82 · November 18, 2019

5 minutes ago, flyingfool said:

you forget about the 3 axis Accelerometer sensor which plays a bit part in calculating power. g-tech and 1/4 mile track testing are very close on HP data

I am aware most use this, and you brought up calculation via sensor data.

Wind resistance is the sort of variable you don’t want with the accelerometer. They are pretty accurate for acceleration figures, but to measure hp they are pretty bad.

I am just trying to make my point that there is no replacement for a dyno.