I'm reading several of Greg Banish's books and just finished reading the "spark hook" test again as a way to find Maximum Brake Torque (MBT) as a function of spark timing. I have a long straight flat hill near my house that seems to work well for slow sweeps under various loads. In the context of my OBD1 $EE 8051 LT1s, it takes time to upload new tunes to the LT1 to vary spark timing and I worry about weather conditions changing too much from run to run to really be comparable. As an alternative, I was pondering perhaps loading multiple PCMs ahead of time, each with the same spark tables but shifted a few degrees relative to each other and then immediately swapping them out between runs.

BUT... As I'm nosing through the various tables in the '94-95 LT1 $EE 8051 setup, I see a "spark correction vs. MAP vs. Coolant Temp." Has anyone ever tried adding a switch into this circuit and then adding a potentiometer or resistor box to the circuit once you got to the test site to command a particular coolant temp and thereby vary commanded spark timing? One could then setup the spark correction table with a particular set of correction factors per temperature and very quickly change resistance values to sweep spark timing within the context of a single run. For example, if the driver held the vehicle speed constant by varying TPS and then varied the coolant temp which forced the spark advance to vary, then all you would have to do after the run is look at the data logs to find the minimum TPS/MAP needed to maintain a given speed. You could repeat this test multiple times at various operating points without the need for multiple tunes or musical PCMs.

Is this feasible? Or quixotic?