JPI 900 HP constants

[larryb]

Has anybody put effort into setting the HP constants to get  an accurate %HP display?  If so, are you happy with the result?

In my Encore I just have the default setting so far. I show 106% on takeoff.   I need to pay more attention to what it shows in both LOP and ROP cruise.

Larry

[kortopates]

Its easy to correct and update - just follow the instructions in the Pilot Guide for doing so. Too many pilots assue the installer calibrated the HP Constant - and think its accurate from the start but that virtually never happens. The other consideration is the unit is computing % power based on a ROP calculation - not LOP. You need to go by simple FF and compression ratio for LOP power. (Incidentally, another engine monitor does calculate % power for both ROP and LOP but I've never missed this on the JPI.)

[larryb]

I've read the manual, and am planning to make the updates. FYI, the manual does discuss different settings for LOP and ROP operation. My question was more of have other folks done this and what their experience was.

 

Thanks, Larry

[DMM]

IO-360 and I am happy with the results.  Its close to 100% on takeoff (depends on DA) and appears to be correct at cruise LOP or ROP.   Based on FF when LOP it's spot on. 

 

Also make sure the MAP is calibrated and the Fuel Flow K factor has been adjusted.  These will affect the HP accuracy. 

Edited November 25, 2019 by DMM
additional info

[0TreeLemur]

Followed the instructions.   Works great on my C.  Agrees with the book.

[Bob_Belville]

I set my 930 back in 2012 when it was installed by the book. It has to be done in flight with reference to the Owners Manual power settings. It remains very accurate - I've never had to change the constant.