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Old 10-24-2018, 08:16 PM
Kellym Kellym is offline
Join Date: Aug 2005
Posts: 89

Originally Posted by tim2542 View Post
I donít believe % power indications from an engine monitor will be accurate when LOP, at least the GRTís use a Lycoming % power table that goes out the window when LOP.
15.7 x fuel flow / rated HP works when LOP.
Edit: that works with 8.5:1 compression ratio, I donít know the number for others C/Rís
Tim Andres
Actually the number for 8.5 to 1 is 15.0 x FF= HP, HP/rated power equals % power. For 200 hp IO360 that is 10gph when LOP for 75%. For 260HP IO540 that is 13 gph =195 hp = 75%.
It looks to me like Dynon is using a FF ratio to MAP and RPM to determine % power. I had a problem with my fuel flow, indicating much higher than actual, and it wouldn't show LOP when so lean engine was stumbling and losing power. Now that I fixed the FF, the LOP/ROP indications appear to match the above calcs. You can't hurt a normally aspirated engine at any mixture setting if you have RPM and MAP where they fit the 65% setting. Once you have achieved LOP with a fuel injected engine, you can add throttle to WOT and you will still be LOP regardless of power generated.
For climb I just roughly adjust mixture to maintain EGTs between 1200 and 1300 until I level off and lean to LOP.
Kelly McMullen
EAA Tech Counselor
RV-10 40866
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