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G3Xpert Query - % Power
- Thread starter kearney
- Start date
G3X Touch % Power
Good Afternoon,
We will display estimated engine power for Lycoming and Continental engines. You must specify what type of engine you have in configuration mode, as well as the engines maximum rated horsepower and RPM. We calculate estimated percent power using manifold pressure, fuel flow, and RPM. All 3 of these are required for % power to display.
Thanks,
Justin
Good Afternoon,
We will display estimated engine power for Lycoming and Continental engines. You must specify what type of engine you have in configuration mode, as well as the engines maximum rated horsepower and RPM. We calculate estimated percent power using manifold pressure, fuel flow, and RPM. All 3 of these are required for % power to display.
Thanks,
Justin
A quick follow up - will the G3X provide reliable % pwr when running lean of peak? i.e. lower fuel flow than the lyc charts state for a given RPM/MAP combination. If so, does it assume an 8.5:1 CR?
Larry
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RV10inOz
Well Known Member
The G3X does do the LOP %, so that is based on fuel flow, and I would guess 8.5:1
For the purposes of knowing roughly your %HP near enough is good enough.
When ROP, it works on Mass air flow, basically MAP and RPM are it.
With any engine monitor, the simple test is go up and fly full rich, at a steady MAP and RPM, then lean all the way to LOP and to ICO. The old JPI's and even the G1000 (I think) would still show the %power of say 75% all the way through to ICO, so long as the MAP and RPM were constant.
Ohh and if you are worried, just run the mixture back up, dont touch anything else. It will relight again.
For the purposes of knowing roughly your %HP near enough is good enough.
When ROP, it works on Mass air flow, basically MAP and RPM are it.
With any engine monitor, the simple test is go up and fly full rich, at a steady MAP and RPM, then lean all the way to LOP and to ICO. The old JPI's and even the G1000 (I think) would still show the %power of say 75% all the way through to ICO, so long as the MAP and RPM were constant.
Ohh and if you are worried, just run the mixture back up, dont touch anything else. It will relight again.
As I've said for several years now, these % HP figures displayed are only estimates, just as Garmin states. Since baro, ignition timing and humidity are not taken into account, they won't be that accurate.
In testing on Les Kearney's RV-10, we found LOP WOT vs. throttled ROP at the same displayed % power did not give the same TAS, therefore the same hp was not being developed.
When I was running engine dynos we always took humidity and baro data before a run to be able to calculate corrected hp. Ignition timing has a large effect on power LOP as we've demonstrated in flight testing as well.
In testing on Les Kearney's RV-10, we found LOP WOT vs. throttled ROP at the same displayed % power did not give the same TAS, therefore the same hp was not being developed.
When I was running engine dynos we always took humidity and baro data before a run to be able to calculate corrected hp. Ignition timing has a large effect on power LOP as we've demonstrated in flight testing as well.
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The G3X does do the LOP %, so that is based on fuel flow, and I would guess 8.5:1
For the purposes of knowing roughly your %HP near enough is good enough.
When ROP, it works on Mass air flow, basically MAP and RPM are it.
With any engine monitor, the simple test is go up and fly full rich, at a steady MAP and RPM, then lean all the way to LOP and to ICO. The old JPI's and even the G1000 (I think) would still show the %power of say 75% all the way through to ICO, so long as the MAP and RPM were constant.
Ohh and if you are worried, just run the mixture back up, dont touch anything else. It will relight again.
Thanks. I do understand it is only an estimate.
