Need to run a GRAPH of IAT vs GPH under constant conditions....AND a GRAPH of coolant temp vs GPH under the same conditions?
In most cases both IAT and coolant temp go up as the engine warms...so you need to test AFTER the engine is warmed up and is stable.
You can vary the coolant temp reading using a pot to add some resistance.
IAT you'd probably need to vary in reality...by routing warmer air? Some have used added resistance though?
You are trying to see WHICH is more correlated with reduced GPH at cruise and engine warm? Or if both are.
You COULD test both at cruise...finding IF there was reduced GPH if they were tweaked...then set up a circuit with the set resistances that you would manually switch ON after cruise conditions were reached?
Or...something like that....you need to be careful about running in too lean of a condition though.
http://www.nonags.org/members/nijqk/Sensor%5Fmods%2Edoc