G3X %Power

Prior to installing the G3X I set power according to a set charts that was given to me. I compared these settings with those in the Cessna manual (C-177) the engine came from. The Cessna charts were pretty limited but showed the charts I had to be accurate.

Now, with the G3X I find a significant difference from the charts. If I set power according to my charts, the G3X consistently shows the power as 5% lower. This seems be to backed up by fuel flows being significantly higher then I would expect from an IO-360 when I set power according to the G3X.

Has anyone else experienced this? Can anyone confirm the accuracy of the G3?

Scott A Jordan
N733JJ
80331 1100 hours, now with Glass!

The fuel flow and % of power are related. Take the time to calibrate your fuel flow ie fly a few legs and carefully compare what you filled vs what you used. Calibrate and that should solve the problem.

Wayne said:

The fuel flow and % of power are related. Take the time to calibrate your fuel flow ie fly a few legs and carefully compare what you filled vs what you used. Calibrate and that should solve the problem.

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I have calibrated my fuel flow, it is now spot on. This is one of the indications that my power is actually higher than the G3X says it is.

Do this test, get up to altitude, set WOT and 2500 RPM. Note the % power, then lean all the way through until all cylinders are Lean of Peak EGT. say about 10-20 degrees. The % power should be 10% less or there about and should vary with fuel flow only. If you can go to idle cut off and not change.....that tells me something.

Keen to know what the result is.

Remember with rich mixtures power is MAP and RPM dependent, Lean mixtures it is fuel flow only.

RV10inOz said:

Do this test, get up to altitude, set WOT and 2500 RPM. Note the % power, then lean all the way through until all cylinders are Lean of Peak EGT. say about 10-20 degrees. The % power should be 10% less or there about and should vary with fuel flow only. If you can go to idle cut off and not change.....that tells me something.

Keen to know what the result is.

Remember with rich mixtures power is MAP and RPM dependent, Lean mixtures it is fuel flow only.

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I plan to do some definitive testing but it will be a couple weeks. The ignition is out for adjustment and I will then be out of town.

Will report back in a couple weeks.

RV10inOz said:

Remember with rich mixtures power is MAP and RPM dependent, Lean mixtures it is fuel flow only.

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Power on a given engine is determined by many variables regardless of whether rich or lean. These include:

MAP
RPM
AFR
Ignition timing
IAT
CHT
Exhaust back pressure which varies with altitude