5% increased gas mileage

[88turboii]

so ive been trying to figure out how to squeeze some extra mpg out of my TII.. trying to break 30mpg. currently running haltech e6k, 750cc primary injectors, RB 3" exhaust, cold intake, 60-1 hybrid turbo. cruising timing is about 27 deg, 0 split at 2500 rpm (60mph). If i keep it under 60 mph, i can get about 28mpg. if the headlights are up or a/c is on, ive found i lose about 1-2mpg each

my buddy mentioned an idea about the keeping secondary throttle plates closed during cruise and i figured i would try it out. Well if you look at the throttle body works, it does not take much to movement to start cracking open the secondary plates, so normally during cruise, they are cracked open. so i reinstalled the 3rd set of throttle plates, which are commonly removed for the TB mod, and i can rig them open or closed with a spring. this will throw your fuel p/w off during boost (map based tune), but its ok in cruise because i just run in closed loop fuel

during my last trip (5 hours driving one way), on the way out i rigged them closed, so only using primary throttle plate. on the way back I rigged them open, which would be how it works from factory fully warmed up. it made a difference of about 2mpg (28 vs 26 mpg), so about 5% gas savings. unfortunately, i had my lights for both trips, so still havnt broken 30mpg

anyway, so the next thing i was going to do is wire in a solenoid to control whether the valves are open or closed. this would be connected to an ECON button in the cabin, similar to modern hybrids. Im thinking you could also wire this to your standalone ECU to trigger dual maps and boost settings