Why is the delivered torque so high?

[mrfister77]

This has to be way off. Can someone please help me understand what's going on? It's an '02 silverado, 5.3 w/all bolt-on's GMPP ASA cam: 226/236 @ .050 110 lsa .525 lift, Yank 3200, stock internals, stock heads+intake+throttle body. The delivered torque output is 510-529ft.lbs. at 90% + throttle. The torque comes in around 28** rpm and stays that way through 6200 (my set shift point) in 1st 2nd and the start of 3rd, I can't go any further with out breaking the law. Am I wrong in thinking that the delivered torque is supposed to be +/- 15 to20 percent? If so, even @ + 20% 529=424. That still seems high for a mostly stock 5.3.

[mrfister77]

Anyone?

[Chris@HPTuners]

the engine torque PID is a calculated number that is based primarily on airflow and EQ Ratio.

Most often "tuning" the airflow higher or lower by changing the MAF table directly makes the calculated torque higher or lower by the same percentage.

It also depends heavily on the differecne between the currnt spark and the MBT Spark table. The MBT Spark is considered the point at which the engine is producing 100% of the calculated torque. The table Torque Loss % vs Spark Retard tells the PCM how much torque is lost due to the spark being less than MBT. AFAIK, GM doesn't calibrate these values for every engine especially LS1's where the accuracy of the torque calculations wasn't super critical.

In your case, your head/cam mods and tuning have most likely changed the airflow and also the MBT characterstics of the engine.

[mrfister77]

OK! That makes perfect sense. Thank you for your very informative answer. Can I still use the Del. torque to reference tuning changes? Even though it's not right it would still yield the same results, to that figure, or do I need to fix my tune to make this more accurate? Thanks.