The engine's timing or spark...
The engine's timing or spark control is programmed on the Spark Control table. Both a low- and high-octane table exists for the tuner.
Maximum Knock Retard VS. RPM VS. Map Table
In order to provide a safeguard against engine detonation, the high-octane table refers to the Maximum Knock Retard vs. RPM vs. MAP table (Knock Retard table) when the computer senses detonation from one of the knock sensors on the engine. In essence, this table measures knock, then correlates it to engine rpm and manifold absolute pressure (MAP) to determine how much timing it is allowed to pull from the high-octane table.
Brian will change the values in the Maximum Knock Retard vs. RPM vs. MAP table to pull 1-4 degrees of timing when knock is detected. According to him, any engine that senses knock of greater than four degrees is either improperly tuned or running an improper octane grade. By pulling a few degrees of timing once knock is sensed, the engine develops less power thereby cooling the combustion chamber without pulling out timing unnecessarily. Although it is possible to change the sensitivity of this table to account for hardware that may cause "false knock," the sensitivity will remain stock for this application.
For the five dyno pulls done on the '06 GTO to create a maximum power/safe tune, the ECM was programmed with 24 degrees of total timing in the high-octane table. While logging the dyno pull on VCM Scanner, the engine registered a maximum of 1.7 degrees of knock. Although this is not excessive, even on the modified tune it would result in total timing being pulled back to 22 degrees. The high-octane table was modified to have 22 degrees of timing and it should be noted that on the final two dyno pulls, no knock was present.
Torque Management
Torque Management (TM) reduces power on all upshifts and downshifts by a percent reduction of available torque, by either closing the throttle blades or using spark reduction. In the GTO, the ignition timing is reduced in an effort to protect the transmission. Six-speed-equipped cars do not have TM programming, but HP Tuners has a tab titled M6 C.A.G.S that allows the tuner to disable the skip-shift functionality.
In the stock high-octane table...
In the stock high-octane table (not shown), the timing from 2,200 rpm at the maximum cylinder flow rate (1.36) progressively moves up from 19 to 22 degrees by redline. Brian Lohse modifies the high-octane table (shown) by locking in 22 degrees from 2,200 to the engine redline. Part throttle timing (low cylinder flow rates) is not changed, but the additional six degrees of timing at higher flow rates adds more power in the indicated rpm range. Although not shown, the low-octane table is modified in much the same manner with the timing bumped from 16 to 22 degrees.
Within the TM functionality is an Abuse Mode, which is programmed to reduce torque starting at low rpm. In the stock programming, the available torque is reduced based on an ECM lookup table under % Torque Reduction vs. Spark. Entering zeros for the values causes the computer to disregard the programmed parameters.
In TM, Torque Reduction vs. Torque vs. Shift table, the factory has pre-set torque percent reductions for each available shift of the four-speed auto trans based on whether the engine is at wide-open throttle or not. Removing the pre-set torque percent reductions will result in all available torque on each shift.
Now that you have some background, follow along with the photos and charts as we take you through the tuning on a 2006 LS2-equipped automatic GTO, owned by Bob Cook of Allen, Texas. The tuning and testing was completed by Real Performance Motorsports (RPM) of Lewisville, Texas using HP Tuners software for the LS2 engine.
Conclusion
Via its tuning on the '06 GTO, RPM was able to gain a peak of 20 horsepower and 17 lb-ft of torque at the rear wheels. Translated into crankshaft numbers, that's almost 30 horsepower.
According to Lohse, "The '05 and '06 LS2-based GTOs respond very well to tuning, in large part due to the conservative nature of the tune that Pontiac puts into the cars. Almost as significant as the horsepower and torque gains are the changes that were made to eliminate torque management. Although not measurable on a dyno, since torque management engages during shifts, the elimination of it allows the cars to pick up .1 to .2 tenths in the quarter-mile while simultaneously giving the owner confidence that he can consistently bracket race without fear of torque management intruding and literally losing the race for you."