LOP setting

[StanN45]

I know this horse has probably been beat to death somewhere, but I'm going to ask anyway. IO550, GAMI injectors, 23 squared (or WOT and 2300), JPI 700 analyzer to monitor,,,,,,what do most like to use, on average, as a LOP setting, 20, 30, 50 degrees LOP...? Or do they all differ in order to run 1250-1350 EGT?

 

[Challenged]

550 here as well, I usually end up anywhere between 25 to 40 when flying LOP but I don't think it matters much as long as the engine as smooth and you aren't making too much power. Here's a graphic, but I don't recall where I snagged it from. It does seem to roughly coincide with most of what I've seen on the topic though.

IO550 Fuel flow, LOP:
11 gph = 55%
12 gph = 60%
13 gph = 65%
14 gph = 70%
15 gph = 75%

 

[wilkersk]

There's a ton of info compressed into one article on the GAMI site: https://gami.com/articles/bttfpart1.php

You might be interested in the advanced pilot course: https://www.advancedpilot.com/onlinecourse.html

 

[DoubleD]

I run the IO-520 at 40-60 deg LOP. The two parameters I use are smooth running and CHTs less than 350 deg. I pay no attention to the absolute value of EGTs in normal operation.

 

[j1b3h0]

I think I read somewhere the most hp per lb of fuel is at 20 degrees LOP. My 520 Bonanza will consume just over 12gph @ 22” 2300Rpm at 20 degrees LOP.

 

[Lance F]

Please keep in mind that at WOT peak is dependent on altitude for a normally aspirated engine. Fuel flows for WOT LOP operation are meaningless without specifying altitude. (Example: for Lycoming IO360 would have peak ~10gph at sea level and ~7.5gph at 12,000'. Your IO520 will be thirstier.) And as DoubleD stated, absolute values of EGT are not how peak is determined.

 

[Tantalum]

Also remember that each engine is going to operate slightly differently. These aren't laser cut precise machines, they're fairly "clumsy" designs.. you have to have an understanding of mixture and watch the temps and use your ears and senses when you settle your engine into cruise flight..
(1) are the temps okay? (CHT and EGT)
(2) does the engine sound okay
(3) does it feel smooth?
(4) is your fuel flow similar to what you expect for a given RPM/MP setting?

What specific setting might work well for someone might not work well for someone else

absolute values of EGT are not how peak is determined

1,000X this.

 

[Jeff767]

EGT values are useful only as a monitor of health on a specific engine. Placement of the probes in the exhaust pipes can cause wide variances even among like engines.

 

[Checkout_my_Six]

I run 25 square at 14 gph.

 

[dwalt]

this is 50 LOP at 6000’. oat 15c. io550