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Leaning While Climbing

mfleming

mfleming

Well Known Member
Patron
I really did search but came up empty.

Here's what should be a basic leaning question. When departing my home field (KJSY) I'm at 5000' by the time I get to pattern altitude. Being such mountainous country, I'm frequently climbing to much higher altitudes. My conundrum is, how do I lean with a constantly increasing altitude? I mean, do you just lean until you're happy and just continue to lean to that value as you climb higher?? I really don't like the idea of waiting till I get to my destination altitude before starting to lean. This confused pilot would really like to know .
 
The thumb rule I use; lean while climbing to maintain EGTs at about what they are at full power during takeoff. So for me this is around 1250 degrees. Once at altitued do the “big pull” and go ~20 degrees LOP. For high altitude takeoff I’ll look for the same 1250 or so EGT once established in the climb. For very hight altitude takeoff the engine is well leaned before the roll to get max power.

I typically take off and climb to 8000-14000 feet. Throttle is wide open from take off to let down at the end of the trip.

Carl
 
if I am taking off from a long runway and do not have mountains around, I cruise climb at peak EGT at 300fpm and 120+ kts.
I did the math, and climbing rich at peak power and Vy saves me merely 3 minutes in trip length but burns 0.5 gal more when I go to 10K
 
PilotjohnS said:
if I am taking off from a long runway and do not have mountains around, I cruise climb at peak EGT at 300fpm and 120+ kts.
I did the math, and climbing rich at peak power and Vy saves me merely 3 minutes in trip length but burns 0.5 gal more when I go to 10K
Click to expand...
You go right to peak EGT the whole time you climb? What altitude do you start this? How long have you been operating this way?
 
mfleming said:
I really did search but came up empty.

Here's what should be a basic leaning question. When departing my home field (KJSY) I'm at 5000' by the time I get to pattern altitude. Being such mountainous country, I'm frequently climbing to much higher altitudes. My conundrum is, how do I lean with a constantly increasing altitude? I mean, do you just lean until you're happy and just continue to lean to that value as you climb higher?? I really don't like the idea of waiting till I get to my destination altitude before starting to lean. This confused pilot would really like to know .
Click to expand...
I do the same as Carl.. but my numbers are a little different, and because I am carburated, I don’t fly LOP. At sea level, full power, full rich, I see about 1320 EGTs. I maintain that in my climb. Around 8500 and above, I start to aim for 1360 EGT. At altitude when the power is 65% or less, I will aim for peak EGT, which is about 1510. So for takeoff at 100% power, I am 190-200 degrees ROP.
 
PilotjohnS said:
if I am taking off from a long runway and do not have mountains around, I cruise climb at peak EGT at 300fpm and 120+ kts.
I did the math, and climbing rich at peak power and Vy saves me merely 3 minutes in trip length but burns 0.5 gal more when I go to 10K
Click to expand...
If I’ve interpreted what you’re saying correctly then that sounds aggressive. Anything near peak EGT at WOT is asking for detonation.

1708475072611.jpeg
 
Carl Froehlich said:
The thumb rule I use; lean while climbing to maintain EGTs at about what they are at full power during takeoff. So for me this is around 1250 degrees. Once at altitued do the “big pull” and go ~20 degrees LOP. For high altitude takeoff I’ll look for the same 1250 or so EGT once established in the climb. For very hight altitude takeoff the engine is well leaned before the roll to get max power.

I typically take off and climb to 8000-14000 feet. Throttle is wide open from take off to let down at the end of the trip.

Carl
Click to expand...
That sounds easy!
 
RV8JD said:
"Target EGT Method" - How to lean your engine for takeoff and climb at any altitude.

Click to expand...
Interesting read. It seems almost too simple. Is a particular EGT number really always the "right" one, day after day, at all density altitudes?

Also, I'm not sure I'm a big fan of playing with the mixture knob during my takeoff roll though, hunting around for some particular EGT.

I did my initial flight training and most of my flying in Florida, so never got practical experience or instruction taking off at high altitudes. All I got was: "When you're at high [how high?] altitude, lean until you get maximum RPM [during runup? during takeoff roll? what if you have a CS prop?], and then lean at altitude as usual." Not exactly a comprehensive education.
 
Draker said:
Interesting read. It seems almost too simple. Is a particular EGT number really always the "right" one, day after day, at all density altitudes?

Also, I'm not sure I'm a big fan of playing with the mixture knob during my takeoff roll though, hunting around for some particular EGT.

I did my initial flight training and most of my flying in Florida, so never got practical experience or instruction taking off at high altitudes. All I got was: "When you're at high [how high?] altitude, lean until you get maximum RPM [during runup? during takeoff roll? what if you have a CS prop?], and then lean at altitude as usual." Not exactly a comprehensive education.
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It is nice and simple. No need to fiddle with anything during takeoff.
At some stage soon after takeoff simply look at your EGT. It should be something roughly 200d rich of peak. Say 1250 or whatever.
Then just slowly pull the mixture back as you climb to keep it at that number. It doesn’t have to be continuous. Every 500’ or even every 1000’ just lean it back to 1250.
It’s way simpler than it sounds!
 
Draker said:
Interesting read. It seems almost too simple. Is a particular EGT number really always the "right" one, day after day, at all density altitudes?

Also, I'm not sure I'm a big fan of playing with the mixture knob during my takeoff roll though, hunting around for some particular EGT.
Click to expand...

The technique I've always followed is to takeoff using whatever settings are appropriate for the density altitude, then take note of the EGT at about 1000 AGL (i.e., when leaving the traffic pattern).

That's my target EGT for the rest of the climb. Whenever it deviates more than 5º or 10º from there, give the red knob a little twist to bring it back on-target.
 
Does anyone watch CHT's if leaning in climb? My rule is if I get to 400° F on any jug I'm leaning a bit to much. I'm running a Lyc carb'd O-360. After I level off, I can lean to peak EGT without running high CHT's
 
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thehagg501 said:
Does anyone watch CHT's if leaning in climb? My rule is if I get to 400° F on any jug I'm leaning a bit to much. I'm running a Lyc carb'd O-360.
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I watch CHTs but when I lean, the CHTs go down once I'm lean of peak. (fuel injected)
 
PilotjohnS said:
if I am taking off from a long runway and do not have mountains around, I cruise climb at peak EGT at 300fpm and 120+ kts.
I did the math, and climbing rich at peak power and Vy saves me merely 3 minutes in trip length but burns 0.5 gal more when I go to 10K
Click to expand...
Edit: I do this above an altitude that gives me less than 65% power and CHTs below 400F below 65% power
 
thehagg501 said:
Does anyone watch CHT's if leaning in climb? My rule is if I get to 400° F on any jug I'm leaning a bit to much. I'm running a Lyc carb'd O-360.
Click to expand...
Absolutely, the point of running richer than peak power EGTs is to provide cooling. If you are at an altitude where the engine is producing less than 75% HP you should be ok. Above 75% HP you need to keep an eye on CHTs.
 
RV8JD said:
"Target EGT Method" - How to lean your engine for takeoff and climb at any altitude.

Click to expand...
+1 for this method.

If you have the chance to takeoff at around sea level, note what your EGTs are and use that as the reference.

My home field is 2200. I'm full everything at takeoff and then lean back to my reference EGTs once I'm about 1000' AGL or higher (1320 for me). Then I just keep leaning back to that every 1000 feet or so in the climb. Once level I lean until I feel the engine start to get rough and dial it back a few turns. (I usually cruise at least 7500 so this is also < 65% power in cruise)

No fuel injection, so I can't really run LOP.
 
thehagg501 said:
Does anyone watch CHT's if leaning in climb? My rule is if I get to 400° F on any jug I'm leaning a bit to much. I'm running a Lyc carb'd O-360. After I level off, I can lean to peak EGT without running high CHT's
Click to expand...
I watch CHTs during the climb, but I primarily control them with AIRSPEED. I’m not impressed with Busch method of leaning reference to CHT. I feel that CHT is more a function of airflow over the cylinders, and EGT is a better indicator of where to set the mixture.
 
The best technique for each airplane is probably going to vary depending on how it's equipped. There are a lot of variables at play when answering the original poster's question. For example:

Carbureted or fuel injected
GAMI vs non-balanced injectors
Fixed pitch vs constant speed
Engine monitor vs analog engine gauges

I have balanced injectors, but a fixed pitch prop. I can't draw 100% power on takeoff or climb with my propeller pitched as it is. So even with full throttle, I'm at a place where I can lean to climb LOP at 75% or less pretty soon after takeoff. If the OATs are not too high, I can do this without the cylinders exceeding 400. The G3X is a big help because it shows power output in percent rather than just giving me a manifold pressure & RPM combo and leaving me to do the math on my own.

--Ron
 
It is surprising that in 2024 we are still having to do this manually with most ignition and fuel delivery system in our engines, but here we are. I'd recommend reading this excellent and seemingly timeless article in Kitplanes by Kevin Horton: https://www.kitplanes.com/determining-engine-power/

If you have a good feeling for how much power you are developing at a particular MP, temperature, pressure altitude, and RPM then you will know what FF you should have. When you adjust for this number depends on if you are really hot and high and need max power on takeoff, or you can start at full rich and gradually reduce FF during the climb. That's what I usually do.
 
rv8ch said:
It is surprising that in 2024 we are still having to do this manually with most ignition and fuel delivery system in our engines, but here we are. I'd recommend reading this excellent and seemingly timeless article in Kitplanes by Kevin Horton: https://www.kitplanes.com/determining-engine-power/

If you have a good feeling for how much power you are developing at a particular MP, temperature, pressure altitude, and RPM then you will know what FF you should have. When you adjust for this number depends on if you are really hot and high and need max power on takeoff, or you can start at full rich and gradually reduce FF during the climb. That's what I usually do.
Click to expand...
Sounds a lot like me. Fuel Flow is the first thing I look at. I tend to start to lean till I just see a small amount of fuel flow decrease then look at other numbers that people look at above.
 
The OP has a lot to ponder with all the replies. In my opinion there is a lot of correct information here, analysis paralysis is fun for some and less fun for others. I enjoy digging into the numbers when I'm in the mood or at a stage where I understand all the workings, but hypothetically speaking if I had one thing to relay to someone new to flying my carb'd O360 is to lean on the ground so much that more then a brisk taxi will kill the engine. Lean in the air to keep all 4 jugs below 400°. I realistically can't begin to pull mixture until I'm below 75% power. My field is 2000 ish msl.

My son is at UND working twords his commercial. They preach leaning to 1450 EGT after reaching altitude. They fly carb'd O360's in newish Archers.

Both methods accomplish my same jug rule. Keep em below 400.
 
thehagg501 said:
... They preach leaning to 1450 EGT after reaching altitude. They fly carb'd O360's in newish Archers...
Click to expand...
If they are targeting a specific EGT, across their fleet, then I wonder if they configured all of their airplanes to have the EGT probes mounted in exactly the same location. I would also wonder what they teach when operating from different density altitude fields away from home base. Of course, there are many opinions and variables here. Since the OP was taking a "survey" of sorts, I operate exclusively as Carl in post # 2 explains, including WOT to the max extent possible. In cruise with a strong headwind, I sometimes opt for ROP/best power. If any CHT exceeds 400, then my first action is to increase airspeed. If the temp does not come down, second action is enrich the mixture. RV-8, IOX-360. I am not an expert, but this has worked well in close to 500 hours and my efficiency and speeds are routinely above my local flying buddies.
 
Michael- try this….

Ground lean to the point that you can barely taxi. Right before your take off roll, go full rich, or nearly. While you’re rolling lean until loss of power or engine stumble. Enrichen until you “feel” like you’re at full power, then enrich a bit more. Watch your EGT’s. If they are rising fast during climb, go more rich, falling, lean.
You will then have a base line to start looking at all the other numbers and you will quickly learn what works at your field.
Detonation of small bore Lycomings is really rare. You’ve heard about all those new low time pilots blowing up engines all the time right? Nope.
Play with it, watch your EGT’s and have fun.
 
I read this tip on VAF. If you have a G3X hit lean find prior to take off. Then as you climb lean to that value.
 
JonJay said:
Michael- try this….

Ground lean to the point that you can barely taxi. Right before your take off roll, go full rich, or nearly. While you’re rolling lean until loss of power or engine stumble. Enrichen until you “feel” like you’re at full power, then enrich a bit more. Watch your EGT’s. If they are rising fast during climb, go more rich, falling, lean.
You will then have a base line to start looking at all the other numbers and you will quickly learn what works at your field.
Detonation of small bore Lycomings is really rare. You’ve heard about all those new low time pilots blowing up engines all the time right? Nope.
Play with it, watch your EGT’s and have fun.
Click to expand...
I can chew bubble gum and walk but I'm not sure I can pull this off 🤣
 
mfleming said:
I can chew bubble gum and walk but I'm not sure I can pull this off 🤣
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Easier than it sounds, but I get it. We’re not fine tooth combing this thing, just getting a rough rich of peak setting without staying full rich.
I do this mixture dance anytime I am at a high elevation field. I want as close to full power as I can get and if you don’t lean at your field elevation for take off, you’re not there. You can get away with it in most RV’s, but if your loaded to gross, high and hot, you want that power.
Leaning during climb is secondary honestly. Generating full power, or as full as you can make it, at high elevation fields might save your butt some day.
(not trying to overdramatize.)
 
thehagg501 said:
lean on the ground so much that more then a brisk taxi will kill the engine. Lean in the air to keep all 4 jugs below 400°.
Click to expand...
This is basically what I do. I would just add that keeping Lycoming cylinders below 400 is actually quite conservative.
 
Dugaru said:
This is basically what I do. I would just add that keeping Lycoming cylinders below 400 is actually quite conservative.
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So, on. 20 degF. day you’re leaning to CHT the same as on a 100 deg.F day?
Or agressive climb vs shallow climb?

Leaning is all about EGT, not CHT.

Pretty much what Dan and others already stated.
 
JonJay said:
So, on. 20 degF. day you’re leaning to CHT the same as on a 100 deg.F day?
Or agressive climb vs shallow climb?

Leaning is all about EGT, not CHT.

Pretty much what Dan and others already stated.
Click to expand...
No, I was probably unclear (or perhaps misunderstood the post I was responding to). I don't "lean to CHT." I lean using the classic technique for carburetors (lean until it gets a little rough, then push the knob back in until it just gets smooth). But I'll enrichen to keep my hottest cylinder in the 400 range as a last resort when needed. This last resort is necessary only on the hottest days, usually if I've made a brief stop somewhere. Usually I just need to shallow out a climb, etc.
 
Dugaru said:
No, I was probably unclear (or perhaps misunderstood the post I was responding to). I don't "lean to CHT." I lean using the classic technique for carburetors (lean until it gets a little rough, then push the knob back in until it just gets smooth). But I'll enrichen to keep my hottest cylinder in the 400 range as a last resort when needed. This last resort is necessary only on the hottest days, usually if I've made a brief stop somewhere. Usually I just need to shallow out a climb, etc.
Click to expand...
Gotcha.
It’s always fun “Forum Flying” isn’t it ;)
 
Draker said:
Is a particular EGT number really always the "right" one, day after day, at all density altitudes?
Click to expand...

I didn't believe this, but fortunately I saved the Garmin logs from every flight I've ever done in N12VD, and lo and behold: the EGT recorded during my wide open throttle takeoff rolls was exactly 1305 varying by only ±15F over the course of 100+ takeoffs, across a wide range of density altitudes and OATs. This is astonishing to me. I just learned quite a bit about EGT and mixture from this thread.
 
Draker said:
I didn't believe this, but fortunately I saved the Garmin logs from every flight I've ever done in N12VD, and lo and behold: the EGT recorded during my wide open throttle takeoff rolls was exactly 1305 varying by only ±15F over the course of 100+ takeoffs, across a wide range of density altitudes and OATs. This is astonishing to me.
Click to expand...

In God we trust. Everyone else, bring data.
 
After takeoff & during climb I lean as needed to keep AFR around 12, which is roughly the “best power” region. If power is above about 65%, I avoid the red region on the AFR gauge, which approximates the “Red Box / Red Fin”. Once at cruise altitude, I do the Big Mixture Pull until I’m well into the LOP green region, with AFR approaching 16.

IMG_2835.jpeg
 
newt said:
The technique I've always followed is to takeoff using whatever settings are appropriate for the density altitude, then take note of the EGT at about 1000 AGL (i.e., when leaving the traffic pattern).

That's my target EGT for the rest of the climb. Whenever it deviates more than 5º or 10º from there, give the red knob a little twist to bring it back on-target.
Click to expand...
I got a chance to try this method yesterday. It work well and it's simple!!
 
Ok. This weekend I tried different methods. My old way of leaning to peak egt during climb wasnt the best.

I ‘ll admit I have been educate. This is where theory fails in practice.

I said above I lean to peak egt during climb, and on paper that makes sense. But in reality I dont like it because it prolongs climb. Once at altitude, i can pull back power to 55%,, go lean of peak and sip 5.5 gph while zipping along.

This weekend it was obvious that my 9A likes to cruise above 10500 msl. It seems to me there is no point babying climb since there appears to be a drastic increase in efficiency above 10500 for my incarnation of this fabulous design.

So lean to maintain peak climb power at 500 fpm once chts settle in at 395F or so. Thats my plan.

Thanks for the thread. It has really helped refine my technique.
 
It seems to me that a lot of folks flying out there do not have a firm grasp on the basics of fuel to air mixture and how it relates to their engine performance.
I think some would do better to ignore their engine monitors and go old school for a while.
As an example, get to your cruise altitude, pull mixture until engine roughness, carburetor, or significant loss of power, injected, and then enrichen until smooth or return of power, enrichen a bit more. Check your EGT’s.
You will be as lean as you can get at that point, if that is what you’re after. No need for an engine monitor to get you there.
For those that know there numbers, try it. You will be surprised how well the numbers match up. I will note it is much easier with a carb to feel the roughness.
 
JonJay said:
It seems to me that a lot of folks flying out there do not have a firm grasp on the basics of fuel to air mixture and how it relates to their engine performance.
I think some would do better to ignore their engine monitors and go old school for a while.
As an example, get to your cruise altitude, pull mixture until engine roughness, carburetor, or significant loss of power, injected, and then enrichen until smooth or return of power, enrichen a bit more. Check your EGT’s.
You will be as lean as you can get at that point, if that is what you’re after. No need for an engine monitor to get you there.
For those that know there numbers, try it. You will be surprised how well the numbers match up. I will note it is much easier with a carb to feel the roughness.
Click to expand...
Jonjay, you are right. But the injected engine goes pretty lean before roughness sets in; probably much leaner than a carb would go. But once one is lean of peak, whether 5F or 50F, the efficiency is the same because horsepower is directly related to fuel flow. So I imagine a carb guy could follow your leaning procedure, and then reduce throttle to get a very high mileage (nautical miles per gallon), since once lean of peak, miles per gallon has to do with horsepower output, whether it is through further leaning, or reduction of throttle; i don't think it matters much.
 
JonJay said:
It seems to me that a lot of folks flying out there do not have a firm grasp on the basics of fuel to air mixture and how it relates to their engine performance.
I think some would do better to ignore their engine monitors and go old school for a while.
As an example, get to your cruise altitude, pull mixture until engine roughness, carburetor, or significant loss of power, injected, and then enrichen until smooth or return of power, enrichen a bit more. Check your EGT’s.
You will be as lean as you can get at that point, if that is what you’re after. No need for an engine monitor to get you there.
For those that know there numbers, try it. You will be surprised how well the numbers match up. I will note it is much easier with a carb to feel the roughness.
Click to expand...
Ya and when you get to lean the motor will die. Letting you know you are to lean for sure. Or just buy an SDS EM-5F fuel injection and electronic ignition system and you can dial in anything you want.
My luck varies Fixit
 
PilotjohnS said:
But once one is lean of peak, whether 5F or 50F, the efficiency is the same because horsepower is directly related to fuel flow.
Click to expand...
Why would you ever go leaner than 5 deg. If you don’t gain efficiency? I’m in an area that I don’t fully understand but it wouldn’t make sense to go slower unless you’re gaining something.
I thought we go lean of peak to gain range, ie, efficiency?
 
Carl Froehlich said:
The thumb rule I use; lean while climbing to maintain EGTs at about what they are at full power during takeoff. So for me this is around 1250 degrees. Once at altitued do the “big pull” and go ~20 degrees LOP. For high altitude takeoff I’ll look for the same 1250 or so EGT once established in the climb. For very hight altitude takeoff the engine is well leaned before the roll to get max power.

I typically take off and climb to 8000-14000 feet. Throttle is wide open from take off to let down at the end of the trip.

Carl
Click to expand...
I used this process this weekend and it was great.

I normally would give a bit of a twist of the mixture every 500’ without being too specific to what I was tracking aside from keeping the CHTs in control. Once at the final altitude, I leaned like normal.
 
JonJay said:
Why would you ever go leaner than 5 deg. If you don’t gain efficiency? I’m in an area that I don’t fully understand but it wouldn’t make sense to go slower unless you’re gaining something.
I thought we go lean of peak to gain range, ie, efficiency?
Click to expand...
With wide open throttle and lots of lean of peak there is a marginal efficiency gain as oppose to just barely lean of peak and then closed throttle. In my io320 it is almost imperceivable, But the engine seems much happier at 5 F lean of peak but throttled back to 55%. That is just my engine and airframe combo. YMMV

PS i am hoping the new G100ul is a higher octane and would allow me to run really lean of peak and/or be smoother when leaned. Cant wait to try it.
 
PilotjohnS said:
With wide open throttle and lots of lean of peak there is a marginal efficiency gain as oppose to just barely lean of peak and then closed throttle. In my io320 it is almost imperceivable, But the engine seems much happier at 5 F lean of peak but throttled back to 55%. That is just my engine and airframe combo. YMMV

PS i am hoping the new G100ul is a higher octane and would allow me to run really lean of peak and/or be smoother when leaned. Cant wait to try it.
Click to expand...
You should be able to go much leaner at WOT with an injected engine at any reasonably cruise altitude. There is a significant increase in efficiency. That’s why we run lean of peak. Many here run WOT and at least 100d LOP or more.
I would suggest balancing your injectors.
Anyway, lots of posts here or simply google away….
Getting too far off topic so I’ll leave you with that and apologize.
 
JonJay said:
It seems to me that a lot of folks flying out there do not have a firm grasp on the basics of fuel to air mixture and how it relates to their engine performance.
I think some would do better to ignore their engine monitors and go old school for a while.
As an example, get to your cruise altitude, pull mixture until engine roughness, carburetor, or significant loss of power, injected, and then enrichen until smooth or return of power, enrichen a bit more. Check your EGT’s.
You will be as lean as you can get at that point, if that is what you’re after. No need for an engine monitor to get you there.
For those that know there numbers, try it. You will be surprised how well the numbers match up. I will note it is much easier with a carb to feel the roughness.
Click to expand...
I know my numbers but typically I do as you suggest without looking at the engine monitor. I then look at the engine monitor to confirm.
 
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