Lycoming leaning technique?

cbmontgo

cbmontgo

Pre-takeoff checklist
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cbmontgo
I know there have been a million discussions and opinions on this matter, but I have a "habit" question to ask regarding leaning and climb out.

I fly a 172S with the O-360-L2A and an older P model with the 0-320-D2J.

Let's say you are departing a field at sea level and want to fly VFR east and climb to, say, 9,500 feet MSL cruising altitude in a 172.

What is your optimal leaning technique from field elevation as you climb to 9,500'?
 
cbmontgo said:
I know there have been a million discussions and opinions on this matter, but I have a "habit" question to ask regarding leaning and climb out.

I fly a 172S with the O-360-L2A and an older P model with the 0-320-D2J.

Let's say you are departing a field at sea level and want to fly VFR east and climb to, say, 9,500 feet MSL cruising altitude in a 172.

What is your optimal leaning technique from field elevation as you climb to 9,500'?
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I have a JPI so I can monitor all the CHTs, I basically lean for max performance while keeping my CHTs under 400. I start leaning as low as 1000MSL. No point in burning more fuel if the CHTs are fine. I keep leaning through the entire climb.
 
ScottM said:
I pull the mixture until the engine stutter and push it in until it stops.
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Doesn't that get a little exciting when the engine stops...or are you just pushing it in until it won't go further?:D
 
I always hear that a Lycoming should not be leaned aggressively above a 65% power setting, so it begs the question...do you climb all the way to 9,500 at full power and lean gradually while climbing? Or, do you level off incrementally to lean the engine at a lower power setting?

Obviously, you would/could not climb to that altitude at full rich.

I am just curious what the consensus is.
 
cbmontgo said:
I always hear that a Lycoming should not be leaned aggressively above a 65% power setting, so it begs the question...do you climb all the way to 9,500 at full power and lean gradually while climbing? Or, do you level off incrementally to lean the engine at a lower power setting?

Obviously, you would/could not climb to that altitude at full rich.

I am just curious what the consensus is.
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Generally you lean while climbing. Keep in mind that the power you're outputting rapidly decreases in a normally aspirated piston in the climb (even with full throttle).
 
cbmontgo said:
I always hear that a Lycoming should not be leaned aggressively above a 65% power setting, so it begs the question...do you climb all the way to 9,500 at full power and lean gradually while climbing? Or, do you level off incrementally to lean the engine at a lower power setting?

Obviously, you would/could not climb to that altitude at full rich.

I am just curious what the consensus is.
Click to expand...

I start leaning right away, there's absolutely no reason to be 700+ degrees rich of peak ever.
 
cbmontgo said:
I always hear that a Lycoming should not be leaned aggressively above a 65% power setting, so it begs the question...do you climb all the way to 9,500 at full power and lean gradually while climbing? Or, do you level off incrementally to lean the engine at a lower power setting?

Obviously, you would/could not climb to that altitude at full rich.

I am just curious what the consensus is.
Click to expand...

On my 182, the POH has a "Normal Climb" power setting of 2400 rpm, 25" MP, and 16 GPH fuel flow, which is substantially less than full rich of 24 GPH. As soon as practical after takeoff, that is what I adjust to until I reach cruise.

I suspect the 172 may also have a designated "Normal Climb" setting. But, I don't know what it would be.
 
gismo said:
During a full power climb?
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I'll pull fast for LOP on my climb power reduction, I don't climb full power exept for take off and to get clear. If I have to climb hard for terrain, I'll pull back to find peak and shove forward for 150 ROP.
 
I've noted what full power EGT is and keep it there until I throttle down.
 
cbmontgo said:
I fly a 172S with the O-360-L2A and an older P model with the 0-320-D2J.
Click to expand...

That'd be IO-360-L2A for the 172S...

Let's say you are departing a field at sea level and want to fly VFR east and climb to, say, 9,500 feet MSL cruising altitude in a 172.

What is your optimal leaning technique from field elevation as you climb to 9,500'?
Click to expand...

I use the Deakin technique - Check EGT at 500-1000 AGL on climbout, and just keep leaning to that number. This does assume that you have proper instrumentation to do so - Though in this case, even a single-probe EGT like the Alcor will work, I think.
 
Our R 172 has a single probe, the only S I've played with was a G1000 though.

The older one is anyones guess.
 
Skylane81E said:
The older one is anyone's guess.
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I've been overhauling and running/flying the 0-300- for many years and on the test cell the 0-300 all 6 cylinders will peak with in 50 Degrees of each other.

on the aircraft they will run the back two cylinders hotter CHT than the front 4, its a cowl problem.

but the fuel flow is the same on all 6.

with EGTs on all 6, #3&4 are the first to peak.
 
Naturally aspirated you can't physically climb at full power. As soon as you start climbing, power starts to drop off.

But it does create an interesting question. You can risk high head temps if you don't have the proper equipment and guess at leaning. Many 172s and Cherokees don't have a CHT or EGT, makes it hard to do any sort of accurate leaning in the climb.

I've seen enough engines try to over-temp when you lean them too aggressively in the climb due to poor cooling. So I won't keep it at full rich, but I'll conservatively pull it back a bit as I get up. Basically try to find best power and then push it rich a bit more. You really are guessing at that point. I also try to do a cruise climb if the plane has enough power to tolerate it.

If you have an EGT or CHT gauge (full on engine monitor is best), it makes it easier.
 
1. Have a good engine analyzer on hand.

2. Depart a sea-level airport, noting your EGT temp as you go wheels-up. In my case that 1,300 degrees.

3. As you climb continue to lean to (in my case) 1,300 degrees, watching CHT's not to exceed 370 degrees (my choice). If the CHT's climb to 370 either lower the nose or add fuel.

If your engine is calibrated to make best power at sea-level and your fuel flow indicates to-spec (oh ya, you DO have a fuel totalizer, right?), (in my case) 19 gph = best power at sea-level = 1,300 degrees on the #3 EGT probe. Therefore 1,300 degrees = best power no matter the altitude. Best power will, of course, decrease with altitude but the fuel/air ratio will remain the same, which is reflected on the EGT display.

This is also good for developing best power from a high altitude airport since you can lean on the rollout to achieve your known best power EGT. Sure is nice to know you're making best power flying off the 2,500 foot strip at 9,500 msl on a hot afternoon!
 
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jimbtv said:
If your engine is calibrated to make best power at sea-level and your fuel flow indicates to-spec (oh ya, you DO have a fuel totalizer, right?), (in my case) 19 gph = best power at sea-level = 1,300 degrees on the #3 EGT probe. Therefore 1,300 degrees = best power no matter the altitude. Best power will, of course, decrease with altitude but the fuel/air ratio will remain the same, which is reflected on the EGT display.
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One bit of note: The majority of engines at full rich mixture setting and rated manifold pressure/RPM are not at a best power mixture setting. Full rich is typically a good bit richer than best power. This exists for cooling purposes. If your fuel requirements are detonation limited, that is built-in to the engine rating. Note that this is not your rated power, however. Your power rating is probably something like:

250 HP @ 2575 RPM at 0.50 lb/hp-hr BSFC

Full rich might be a 0.65 lb/hp-hr BSFC, but that's a function of the rich limit for the carburetor or fuel servo.
 
ScottM said:
I pull the mixture until the engine stutter and push it in until it stops.
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I sort of do this. But Gary's plane has a vernier knob so I pull then twist then when it goes rough twist back in till it smooths out.
 
Based on some of the stuff posted here, it seems to me that a bunch of CFI's are turning out pilots who lack even the basics of leaning properly (with or without a fancy instrument) I suspect those CFI's need more dual...

denny-o
 
Dr. O said:
Based on some of the stuff posted here, it seems to me that a bunch of CFI's are turning out pilots who lack even the basics of leaning properly (with or without a fancy instrument) I suspect those CFI's need more dual...

denny-o
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Basicly:mad2:
 
Let me say that I "just" started reading Deakins' leaning articles. Seems like is credible information.

Ted DuPuis said:
Full rich is typically a good bit richer than best power. This exists for cooling purposes.
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Based on what I'm reading in Deakins, your statement is common thought but disagrees with what Deakins espouses.
 
Dr. O said:
Based on some of the stuff posted here, it seems to me that a bunch of CFI's are turning out pilots who lack even the basics of leaning properly (with or without a fancy instrument) I suspect those CFI's need more dual...
Click to expand...

That is correct. I have found very few pilots are equipped for piston flight.

Jaybird180 said:
Let me say that I "just" started reading Deakins' leaning articles. Seems like is credible information.
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He receives credibility because he has a lot of time flying airplanes that most of us wish we would be allowed to fly. Some of his advice is good, some of it is not.

Based on what I'm reading in Deakins, your statement is common thought but disagrees with what Deakins espouses.
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It varies depending on engine model. But typically for a naturally aspirated Lycoming engine, this is the case. Probably more like an 0.60 rather than an 0.65, but rated power will be 0.48-0.52 range. Continentals may be another story, and I don't know about the setup on their fuel systems.

As it related to Jim's comment on what he flies (and to the OP), this is correct.
 
To me, it depends on how high I'm going.

climbegt.jpg


The above data (JPI 700) shows my EGT during climb (starting at 1000' AGL) and stopping at 5500' MSL (I dropped the climb RPMs to 2500 or so shortly after busting through pattern altitude). Notice that the EGTs only decreased an average of 85 degrees or so and CHTs were fine the whole way up. So with this small of an EGT change, I personally don't bother leaning during a climb to 5500'. But If I were going higher, somewhere around this point, I'd pick an EGT and run it up 100 degrees or so by leaning. And I'd do this repeatedly as I climb and as EGTs cool another 100 degrees.
 
Single point Alcor and an FS-450 fuel flow meter on an O-360 Lyc. 172. No need to make this more complicated than it has to be folks. Lean in climb to maintain reasonable power, fuel flow and EGT temps. At cruise, to the OP, understand that each plane will have it's own sweet spot for leaning purposes. Go back to the tried and true lean till rough and then smooth it out slowly. Over my time in my plane, I have watched the values in fuel flow and EGTs during this process and know where the values should be. BTW I was also taught that the reverse applies when descending: to enrichen the mixture gradually as you descend. My A&P sez that the engine will reward me in the long run for treating it gently. YMMV
 
I was taught, never lean below 3000', then lean on climb at less than 2400RPM for peak rpm. This is generally less than 70% power. Engine O-320-H2 (matches the POH procedure)

By habit, I will typically not lean until Im at altitude for FL5500 and below. On climb to higher altitudes, Ill lean slowly every 1000ft or so to get peak RPM.

But Im not paying for fuel since the plane rents wet. Just don't want to foul a plug and get the best performance possible.
 
JohnAJohnson said:
To me, it depends on how high I'm going.

climbegt.jpg


The above data (JPI 700) shows my EGT during climb (starting at 1000' AGL) and stopping at 5500' MSL (I dropped the climb RPMs to 2500 or so shortly after busting through pattern altitude). Notice that the EGTs only decreased an average of 85 degrees or so and CHTs were fine the whole way up. So with this small of an EGT change, I personally don't bother leaning during a climb to 5500'. But If I were going higher, somewhere around this point, I'd pick an EGT and run it up 100 degrees or so by leaning. And I'd do this repeatedly as I climb and as EGTs cool another 100 degrees.
Click to expand...

The chart is very interesting...I just had a JPI 730 installed but haven't had a chance to fly more than a 30 min. "just to see what it does" trip. I noticed the same EGT characteristics - #3 was over 1400 in climb, the other 3 were comfortably in the 1350 area. I really need 3-4 trips of over an hour each to learn both about the 730 and how to better use it.
 
Jaybird180 said:
Let me say that I "just" started reading Deakins' leaning articles. Seems like is credible information.



Based on what I'm reading in Deakins, your statement is common thought but disagrees with what Deakins espouses.
Click to expand...

Links to articles?
 
TripleZ said:
I was taught, never lean below 3000', then lean on climb at less than 2400RPM for peak rpm. This is generally less than 70% power. Engine O-320-H2 (matches the POH procedure)

By habit, I will typically not lean until Im at altitude for FL5500 and below. On climb to higher altitudes, Ill lean slowly every 1000ft or so to get peak RPM.

But Im not paying for fuel since the plane rents wet. Just don't want to foul a plug and get the best performance possible.
Click to expand...

FL5500 - that's 550,000 ft. :goofy: The O-320 is a rocket? What airframe?

I'm sure you meant FL055. ;)
 
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