[Pat Hatch]

Just curious, what kind of K factors are folks getting with their G3X using a FT-60 Red Cube transducer? I noticed that the default K factor in the G3X calibration page was 68,000. I have now bumped it up to 71,179 after several long legs over 3 hours indicated that I was actually using about 1.3 gallons less than what was being indicated on the fuel page. What's yours?

I don't think engine type should make any difference, but mine is an O-360-A1A carbureted.

 

[g3xpert]

Boost pump?

Hi Pat,

How much do you fly with the electric boost pump on?

Myself and others (with carburetors) notice that the fuel flow is always exaggerated when the boost pump is on, but looks "normal" when just running on the mechanical pump. Must be fuel pump pulses affecting the turbine vane inside the flow sensor.

Steve

 

[Pat Hatch]

Hi Steve,

Funny you should mention that. I did notice that every time I turn the boost pump on, the fuel flow jumps up slightly. I wasn't sure why that was, but what you say makes sense. I don't think the actual fuel flow is increasing, just an indication issue, I guess. Anyway, I don't think the error is appreciable for the short times that I have the pump on--usually just during takeoff and landing.

I can see where the 'fuel used' numbers would be more accurate for the longer legs, in part for this very reason.

I do note that my fuel indicating system is very accurate with the capacitance sending system that I have (Van's), compared to the E.I. indicators I had before. The G3X system rounds to the nearest gallon whereas the E.I. system rounded to the nearest 2 gallons. Also, the G3X calibration protocol is a lot more sophisticated. I have the curves for both in flight and on the ground (taildragger). Works well.

 

[MarkW]

Pat,
I started at the default 68k and then adjusted to about 69.5. I later moved it back down to about 69.3. This is from memory but very close. My fuel number are darn near perfect now.