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Input on leaning

G

grumman41

Active Member
I’m looking for input on leaning with the Advanced flight system EFIS. I’m including my aircraft setup and flight background.
RV6, IO 320, CS prop, CHT and EGT monitoring.
Ive got a lot of experience in normally aspirated and turbo motors but for the most part it has been jets and turboprops for a long time. Most of the recips I flew had no or poorly calibrated gauges so we operated accordingly. This is really the first recip I’ve flown with complete and calibrated gauges.
 
I would start without the EFIS specific leaning tools. Learn to lean with just the EGT readings first. Many posts here on how and when to lean. Probably as many opinions on that as colors in a rainbow though. Need to search and read a lot about this and a few consistent themes emerge out of the emotion,re-hash and bad data. There is not really one way to do this. A lot depends upon goals and some approaches can create limited risk if used improperly.

Definitely take the time to learn. Your engine and your wallet will thank you.

Larry
 
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You're going to have to determine what you want to lean to. If you want to run ROP +x, you would lean until the first EGT peaks and used that as your reference EGT. If you want to run LOP -x, you would use that last EGT to peak as your reference EGT.
 
It might depend on whether your engine is fuel injected or carbureted. In my 7A (sold) I had trouble going LOP with the carbureted engine. However with fuel injected Lancair I had, LOP was fine. In the carbureted 7A I found that leaning via EGT worked well, normally I leaned to around 1325 for the hottest cylinder (usually#4). An old wives tail is keep EGT + CHT below 1800 and you'll be fine. Of course your experience may vary.
 
First thing I would do (did do) is run a GAMI Leaning test. If the EGT spread between cylinders is too great, running LOP may not be possible or desirable. Such a problem can be remedied by changing to matched injectors. I had a kind of high EGT spread and didn't go the matched injector route, limiting my ability to run LOP. Rather, I lean until I get the EGTs around 1300 or so and the fuel flow is about what I expect

AFS EFIS's have a Leaning EGT Mode (Peak Detect) you can engage that will aid in running LOP safely, as long as the EGT spread isn't too great.

Here's Lycoming's take on leaning. https://www.lycoming.com/content/leaning-lycoming-engines
 
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Something to remember when you experiment.
When you are operating below 65% power you cannot really do any damage with your leaning experimentation no matter where you place the red knob.
It is a good way to find your best and most desirable results, be that going as fast as you want to go or use as little gas as possible or achieve your most ideal temperatures or any combination thereof.
Above 65% you have some envelops to avoid when going from the rich side to the lean side.
Lots of info on the subject as others have pointed out.
 
grumman41 said:
I’m looking for input on leaning with the Advanced flight system EFIS. I’m including my aircraft setup and flight background.
RV6, IO 320, CS prop, CHT and EGT monitoring.
Ive got a lot of experience in normally aspirated and turbo motors but for the most part it has been jets and turboprops for a long time. Most of the recips I flew had no or poorly calibrated gauges so we operated accordingly. This is really the first recip I’ve flown with complete and calibrated gauges.
Click to expand...
My technique is to takeoff full throttle, full prop and full mixture. Note the EGT on any cylinder, doesn’t really matter which one, they should all be rich enough to be safe. Then as you climb, you adjust the mixture control to maintain that number in the climb. (You will control CHT with airspeed, just lower the nose for 110 to 130 knots as appropriate to keep the CHTs where you want them.) when you get to your cruising altitude, level off and accelerate, throttle back the MP if you want (18 to 22 inches works fine), dial back your prop to where you want, then play with the mixture. Lean till it gets rough, enrichen to smooth it out , maybe go a little richer or leaner, depending on what you are trying to achieve. Under 65%, you are probably safe to explore your peak EGTs, then use that peak number to reference off of. You can fly peak at 65% power and below, or above 65%, you can use this chart.

Edit: because of the efficiencies of the Vans intakes, I add 2,000 feet to the chart numbers. ie; 100 degrees ROP at 6,500 feet.
 

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Thanks for the input gentlemen. Many summers have passed but use to fly the six cylinder Continentals in a skydive operation. It’s what local engine folklore would say is the worst possible scenario for a large engine. Wide open power, leaning soon into the climb and power to idle for the decent. I seen one new engine go to TBO with no cylinders replaced and never a cylinder replaced on other big sixes while I was there. The best I remember was referencing pitch, one cylinder head gauge and fuel flow numbers.
 
Grumman41,

Which AFS EFIS is installed? Advanced Flight Systems has an outstanding video on exactly how to use the Lean/Rich modes. Everyone has their own technique so you’re gonna get a lot of differing views but here’s my technique (notice I did not say procedure- this is only one way). AFS video link at the bottom. I have an AFS 5500EFIS and the instructions in this video work well for me. You’ll also have to make sure your engine settings in the EFIS calibration pages are properly selected. I don’t usually cruise down low so these numbers may change based on your altitude, I usually cruise 8-10k
  • For best speed 100 degrees ROP. ROP is done from the one that peaks peak first, then you richen based off it so that it will be the hottest/leanest (nearest to peak EGT) cylinder and the rest will be colder/richer.
  • For best economy 20 degrees LOP. Use the last cylinder to peak, so it is the hottest/richest (yet still nearest to peak EGT) and the rest will be colder/leaner.
Here’s the video:
 
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I spoke with the folks from Gami at OSH a few years ago. I was told the best LOP was 5-10 degrees lean. You get economy without much loss of power.

Do the spread test first and tweak the injectors If needed. Once gal/hr is balanced between the cylinders, you will find the sweet spot for the RPM you like to use and the different altitudes.

For example, I know that at 8,000’ fuel flow rate is around 13.1 gal/hr. I don’t use the lean find function and just dial 13.1gal/hr in and then make minor adjustments to get the cylinders balanced.

Cylinders run cooler and this helps on hot summer days.

My personal experience with flying LOP - I flew my last continental (with Gamis) 700 hrs past TBO. Compressions were in the 70’s but everything else was wearing out.
 

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OK, simple education tool.

My mate John Deakin wrote these many years ago. Article 63-67. Plenty of others to read also but these answer your question.

www.avweb.com

Pelican's Perch #63:Where Should I Run My Engine? (Part 1)

In his many columns about how to lean, whether to use full power after takeoff, oversquare operation and so on, AVweb's John Deakin has left many of the details up to the pilot/owner. Yet many readers would just as soon have him tell them exactly how to set up and run an engine. In this month's...
www.avweb.com www.avweb.com

As for how much LOP,or ROP to be, that is simple.

  • At 65% power, use richer than 100 ROP, or leaner than peak EGT.
  • At 70%, use richer than 125ºF ROP, or leaner than 25ºF LOP.
  • At 75%, use richer than 180ºF ROP, or leaner than 40ºF LOP.
  • At 80%, use richer than 200ºF ROP, or leaner than 60ºF LOP.
 
Great info, thanks gents. I quickly read a post from Joe Blank ( my aircraft builder) concerning power settings and leaning. I meant to save the link but not having any success searching hear. It may have been elsewhere, if anyone comes across it please forward.
 
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