G SERIES PILOT’S GUIDE .
INSIGHT
INSTRUMENT CORPORATION BOX 122, FORT ERIE, ONTARIO, L2A 5M6
35
T.H.P.
Theoretical Horsepower Display
The horsepower display has been improved and requires explanation. First the HP display depends on three configuration
parameters and these need to be set correctly.
The (1) Max RPM, (2) Engine HP and (3) turbo configuration are set to match your engine.
(1) Typically max RPM is 2700.
(2) For turbo’d engines we have a new configuration identifier - a digit followed by “B”. You may choose 0, 1, 2, 1B, 2B.
The B means boosted. When absent it implies turbo-normalized. If your engine manifold pressure can exceed 30 inches
then choose boosted.
(3) The HP calculator has takeoff and cruise modes. Any RPM within 125 of max is considered takeoff. Anything below
that is cruise mode. As we have said before this is theoretical HP not real HP. It will not identify engine faults. Without a
torque sensor on the engine there is no such thing as a real HP reading.
If the Engine HP parameter is set incorrectly it will distort the percentage HP calculations.
The HP algorithms do the best they can to predict engine power even though some essential information is missing.
The display now shows power in either yellow or white. When the incoming information is favorable and will yield a good
result it will display the value in white.
So what are the favorable conditions?
The instrument needs fuel flow, RPM, peak EGT and all the configuration data set correctly. If it doesn’t have peak EGT
because you haven’t leaned yet, like during take off and climb, then it assumes you are leaning correctly on the way up.
Once you reach a good peak EGT the HP calculations will work well. Peak in this case means you have all the lean boxes
displayed above the columns. Once you reach this point, leaning past peak or going back to the rich side of peak will still
produce good HP indications. The value will display in white. If you operate outside of normal parameters the HP will be
less accurate even though the display may still be white. When you change manifold pressure the fuel air ratio will be
approximately the same but to the extent that is not the HP accuracy will compromised. The HP calculations work best
during leaned for cruise operation, where they are most useful.
G3 and G4 single looks like this.
G4 twin looks like this.
