Leaning Best Practice for newbie

[DualRatedFlyer]

8 minutes ago, jaylw314 said:

I'd also point out that's where Continental says you can lean to your heart's content, whereas Lycoming says you can do so below 70%.  I think I remember that from one of Deakin's articles

My POH specifics not to lean above 75% power.  

I wasnt aware that 65% is the magic number where mixture setting becomes less critical.  Guess I could imply that from his charts, but I always run 75% power and havent really considered running at a lower power setting unless altitude dictates it.  Was just curious why 65% was being recommended. 

[Shadrach]

6 minutes ago, jaylw314 said:

I'd also point out that's where Continental says you can lean to your heart's content, whereas Lycoming says you can do so below 70%.  I think I remember that from one of Deakin's articles

Not sure about Lycoming, but my late sixties era POH advises against any leaning below 75% HP without an EGT gauge installed. It further states that if the aircraft is equipped with an EGT gauge, leaning should be limited to no less than 200ROP at 75% or above.  For cruise at less than 75% it recommends 100ROP for best power or 25ROP for best economy. That's not horrid advice considering the era and the equipment, but it's not great either. We can do much better now!

[Shadrach]

56 minutes ago, DualRatedFlyer said:

My POH specifics not to lean above 75% power.  

I wasnt aware that 65% is the magic number where mixture setting becomes less critical.  Guess I could imply that from his charts, but I always run 75% power and havent really considered running at a lower power setting unless altitude dictates it.  Was just curious why 65% was being recommended. 

It's pretty conservative for the IO360.  The engine has healthy detonation margins. I think it would require some serious effort (abuse) to induce actual detonation...Like say climbing out at full throttle pitched for 75MIAS, with the cowl flaps closed, in August, in Pheonix, while leaned to 50 ROP.   This is not to say that you can't over temp an IO360, it's very possible in hot weather at steep climb angles and low speed, but detonation in these engines is a rarity.

Edited October 24, 2018 by Shadrach

[Oldguy]

2 hours ago, Shadrach said:

What's the humidity on a standard day?

Standard.....

Sorry, I could not help myself. It has just been one of those days. 

[jaylw314]

46 minutes ago, DualRatedFlyer said:

My POH specifics not to lean above 75% power.  

I wasnt aware that 65% is the magic number where mixture setting becomes less critical.  Guess I could imply that from his charts, but I always run 75% power and havent really considered running at a lower power setting unless altitude dictates it.  Was just curious why 65% was being recommended. 

65% and 70% were not limits, they were just statements from Continental and Lycoming that ANY leaning was fine and would not produce detonation (IIRC, the 70% number was from a general Lycoming publication, not a SB or anything).  @Shadrach is right, the IO-360 has ridiculous detonation margins, so even those numbers are probably conservative in terms of detonation, although there may be a question of cylinder longevity.

You can certainly lean above 70%.  Heck, you can lean above 75%--IIRC, Lycoming's publications recommend leaning to best power during climb once you're above 5000'.  You've just got to be more careful and have more information

Edit: I did double-check, the POH specifies leaning below 75% during cruise.

[Shadrach]

4 minutes ago, jaylw314 said:

65% and 70% were not limits, they were just statements from Continental and Lycoming that ANY leaning was fine and would not produce detonation (IIRC, the 70% number was from a general Lycoming publication, not a SB or anything).  @Shadrach is right, the IO-360 has ridiculous detonation margins, so even those numbers are probably conservative in terms of detonation, although there may be a question of cylinder longevity.

You can certainly lean above 70%.  Heck, you can lean above 75%--IIRC, Lycoming's publications recommend leaning to best power during climb once you're above 5000'.  You've just got to be more careful and have more information

Edit: I did double-check, the POH specifies leaning below 75% during cruise.

I lean at negative DAs in the winter time. In these parts on a cold winter day the DA can be -500 at 3000msl.  At lower altitudes I lean to rough (~ 80LOP) and enrichen enough to keep my coldest CHT above 280df. Usually end up between 35-45LOP.

[gsxrpilot]

Ok... just to be clear (who said that?)

"Aggressive Leaning", "LOP", or any other version of that... is not the problem. The problem is not leaning ENOUGH. 

So the reason for recommending 65% is that running at Peak or very close to Peak by not Leaning enough is not a danger at that low power setting. 

In my airplane, at 75% power, I need to be at least 25° LOP. I'd like to give that a little margin so I say 30° LOP is the minimum for me at 75% power. At higher power, I just have to be even Leaner.

But when you're learning to do this, learning to find peak, how to calculate degrees LOP, which cylinder is the right one to watch, etc? It's safe to play around with it at 65% power or less.

Running at Peak or close to Peak EGT is what causes engine issues such as detonation, over heating, excessive ICP, etc. 

[Shadrach]

22 minutes ago, gsxrpilot said:

Ok... just to be clear (who said that?)

"Aggressive Leaning", "LOP", or any other version of that... is not the problem. The problem is not leaning ENOUGH. 

So the reason for recommending 65% is that running at Peak or very close to Peak by not Leaning enough is not a danger at that low power setting. 

In my airplane, at 75% power, I need to be at least 25° LOP. I'd like to give that a little margin so I say 30° LOP is the minimum for me at 75% power. At higher power, I just have to be even Leaner.

But when you're learning to do this, learning to find peak, how to calculate degrees LOP, which cylinder is the right one to watch, etc? It's safe to play around with it at 65% power or less.

Running at Peak or close to Peak EGT is what causes engine issues such as detonation, over heating, excessive ICP, etc. 

Paul,

I actually find that CHTs start to drop precipitously on the lean side of 50ROP.  Peak EGT is an underrated power setting in my opinion. It yields CHTs in the same range or lower than 100ROP but with better BSFC and is typically nice and smooth.

[gsxrpilot]

2 minutes ago, Shadrach said:

Paul,

I actually find that CHTs start to drop precipitously on the lean side of 50ROP.  Peak EGT is an underrated power setting in my opinion. It yields CHTs in the same range or lower than 100ROP but with better BSFC and is typically nice and smooth.

That's interesting. I've not seen that. But I'd be very leery of running at say 75% at Peak. That would put you right in the middle of the Red Box/Fin most of the time.

Flying a N/A engine, I'd regularly run right at Peak but I was typically high enough to be at very low power. 12K or 13K in an M20C will be well below 65% power. So peak is a great place to run.  But with my turbo, I set the % power regardless of altitude. So I tend to be a bit more cautious. I either run 75% and 100° ROP or 65% and 30 to 35° LOP. Either way, my cylinders stay cool and I'm just babying my engine. And with 1500 hours on the original cylinders, I feel like it's time to baby it all the way home to TBO.

[Shadrach]

1 hour ago, gsxrpilot said:

That's interesting. I've not seen that. But I'd be very leery of running at say 75% at Peak. That would put you right in the middle of the Red Box/Fin most of the time.

Flying a N/A engine, I'd regularly run right at Peak but I was typically high enough to be at very low power. 12K or 13K in an M20C will be well below 65% power. So peak is a great place to run.  But with my turbo, I set the % power regardless of altitude. So I tend to be a bit more cautious. I either run 75% and 100° ROP or 65% and 30 to 35° LOP. Either way, my cylinders stay cool and I'm just babying my engine. And with 1500 hours on the original cylinders, I feel like it's time to baby it all the way home to TBO.

My experience mirrors what the attached graphs from both GAMI and Lycoming portray (see my notes in yellow and red). Peak is slightly cooler, kinder and way more efficient then 100ROP.  In a NA carburetted engine, if you can get your richest cylinder to peak, you're doing about as well as could be hoped for. Which is where lean it until it's rough and enrichen to smooth would put most O360s. In a TSIO, peak ought to be just as kind as 100ROP (if not more so) provided TIT remains below red line. It's certainly cleaner.

Edited October 24, 2018 by Shadrach

[gsxrpilot]

Ross, 

No argument here. I would just suggest that ensuring you are measuring the EGT of the correct cylinder is critical to this working.  If you identify peak as the first cylinder to peak, then the others are all in the danger zone just rich of peak. Of course if you use the last cylinder to peak, then the other cylinders would be leaner. 

Also at high power settings, the boys at GAMI have created detonation at peak EGT. Thus the admonition to only use that at lower power settings. I saw it when I attended the APS class there a year ago or so.

[takair]

Just to complicate matters, I think mag timing effect on cylinder pressure is under-rated in the leaning discussion.  When Lycoming came out with the he 20 degree timing service bulletin, the intent was to avoid detonation under almost all conditions below 75% power.  I assume this means a smaller or no red box.  25 degree timing, preferred by many for LOP and better  power output, is more sensitive to the higher pressures that can create detonation.  Would be curious if GAMI ever did any detonation testing with the timing set closer to TDC (ie 20 degrees). I suspect the size of the red box would decrease.  With 20 degree timing, I find I can maintain low CHTs, thus further from detonation, at almost any Mixture setting.  25 degree is more sensitive to mixture with respect to CHTs.  In the end it is a trade off.  I recognize that turbo operation is a different world.

Rob

[Shadrach]

1 hour ago, takair said:

Just to complicate matters, I think mag timing effect on cylinder pressure is under-rated in the leaning discussion.  When Lycoming came out with the he 20 degree timing service bulletin, the intent was to avoid detonation under almost all conditions below 75% power.  I assume this means a smaller or no red box.  25 degree timing, preferred by many for LOP and better  power output, is more sensitive to the higher pressures that can create detonation.  Would be curious if GAMI ever did any detonation testing with the timing set closer to TDC (ie 20 degrees). I suspect the size of the red box would decrease.  With 20 degree timing, I find I can maintain low CHTs, thus further from detonation, at almost any Mixture setting.  25 degree is more sensitive to mixture with respect to CHTs.  In the end it is a trade off.  I recognize that turbo operation is a different world.

Rob

I’m pretty sure that Gami is able to run a number of ignition timing scenarios on their test cell.

[carusoam]

Mapa is where you go to learn to define %bhp by adding MP and rpm/100...

Each engine/aircraft has its own key numbers...

The coolest part about LOP... the hp calculation is based on FF.  

Got a FF/totalizer and an engine monitor?

Best regards,

-a-

[FastTex]

19 hours ago, 201er said:

How the heck did you come up with 2400/24?

Just go WOT anywhere above 3000ft, 2500RPM, and bring the mixture back to 8-8.5GPH and you'll be golden. If you want more power, then you'll have to learn a thing or two about engine management, detonation, and leaning.

This sounds so easy to do. Is it a general best practice even for the M20F? I'm still trying to understand what's best to do and this approach sounds like a great first step. Can I just increase the RPM and Mixture to gain more power if, for example, need to climb to 10000'?

[Shadrach]

3 hours ago, FastTex said:

This sounds so easy to do. Is it a general best practice even for the M20F? I'm still trying to understand what's best to do and this approach sounds like a great first step. Can I just increase the RPM and Mixture to gain more power if, for example, need to climb to 10000'?

This is best practice in any naturally aspirated injected engine. Generally speaking there is no reason to operate at anything less than full throttle for take off, climb and cruise. I know some of the old POH’s reccomemd climbing at 26 squared, but that is not a limitation, it’s a recommendation (and not a very good one). I take off and climb at max power. I sometimes reduce RPM temporarily in climb for noise abatement if I am contending with an airspace or ATC climb restriction.  Upon getting to altitude I reduce to 2500,  trim the airplane and begin leaning to desired mixture setting. The procedure is the same whether I’m cruising at 3,000 or 12,000.

you should read the previously linked columns by John Deakin. They are titled “Where should I run my engine?” and they do an admirable job of answering that question.

Edited October 25, 2018 by Shadrach

[FastTex]

7 minutes ago, Shadrach said:

This is best practice in any naturally aspirated injected engine. Generally speaking there is no reason to operate at anything less than full throttle for take off, climb and cruise. I know some of the old POH’s reccomemd climbing at 26 squared, but that is not a limitation, it’s a recommendation (and not a very good one). I take off and climb at max power. I sometimes reduce RPM temporarily in climb for noise abatement if I am contending with an airspace or ATC climb restriction.  Upon getting to altitude I reduce to 2500,  trim the airplane and begin leaning to desired mixture setting. The procedure is the same whether I’m cruising at 3,000 or 12,000.

you should read the previously linked columns by John Deakin. They are titled “Where should I run my engine?” and they do an admirable job of answering that question.

Great, thanks. At what speed do you usually climb? I need to watch my oil temp which has the tendency to go to >210 easily but I can control it if I lower the RPMs...maybe staying at WOT can help? 

[Bob - S50]

3 minutes ago, FastTex said:

Great, thanks. At what speed do you usually climb? I need to watch my oil temp which has the tendency to go to >210 easily but I can control it if I lower the RPMs...maybe staying at WOT can help? 

Just another point of input/technique for you.

1.  The oil temp limitation for my '78 J is 245F, so 210F would not be a problem.  Mine runs in the low 200's all the time and that is good because it helps cook the water out of the oil.  I would think that oil temp would be correlated to power output, air temp, and air density.  It will tend to be higher when you produce more power, at higher altitudes, and higher OAT's.  Since reducing MP, RPM, and running further LOP all reduce power; they should all also reduce oil temp.

2.  I usually climb at 110 - 120 KIAS, full throttle, 2700 RPM, and leaned to a target EGT as suggested by Deakin.  Since I live below a class B airspace, I tend to climb at 120 initially to reduce my rate of climb and get me out from under the 3000' shelf more quickly.  Once clear of that I tend to climb at Carson's number which is about 115 KIAS until my climb rate drops to 500 FPM.  At that point I maintain 500 FPM until I'm down to 100 KIAS at which point I climb at 100 KIAS.

3.  My engine is the A3B6D type which is timed at 25 BTDC.  For cruise, I use 2600 RPM and either 22" or WOT whichever gives me the lower MP.  So below about 7000' or so, I'm using 22" and above that I'm WOT.  I lean to just barely LOP on the richest cylinder.

You'll just have to experiment and find what you and your engine like.

[carusoam]

Mixture Topics to read up on...

0) lean on the ground to avoid build ups on the plugs.

1) LOP, fuel air ratio, CHT cooling...

2) Ignition timing what makes 25°BTDC desirable...

3) Leaning in the climb to altitude... blue/white box EGT methodology.

4) Target EGT for departures at higher altitudes than SL...

5) lop can be used in all phases of flight, During cruise and descent has the most value, least risk...

6) old POHs gave advice to run 50°ROP and ignored LOP... these were funky pieces of advice at best...

7) CHT control is everything. <380°F is preferred by many...

8) avoiding The red box is very important.

9) high powered climb, target 120 to get a decent rate balanced with chts...

10) Gumps... make sure the mixture is in for go around...

bonus points...

11) Gami spread...

12) Savvy.com

13) learn how to post your engine monitor graphs.

 

PP thoughts only, not a mechanic...

Best regards,

-a-

[201er]

4 hours ago, FastTex said:

This sounds so easy to do. Is it a general best practice even for the M20F? I'm still trying to understand what's best to do and this approach sounds like a great first step. Can I just increase the RPM and Mixture to gain more power if, for example, need to climb to 10000'?

As long as the compression ratio on F is same as J. I think it is but someone who has one should confirm.

8.0gph is 60% power at lean of peak. Very economical, cool, can’t hurt the engine no matter how you leaned to get there. Just not enough fuel to make enough power to do anything wrong. Going any slower doesn’t pay. This setting takes you just a little over Carson’s speed.

8.5gph is 65% power at lean of peak. Economic with a little more speed probably the best bang for the buck while still running cool.

10.0gph when lop makes 75% power but if you don’t lean correctly you could run into detonation or just be trashing your engine. Temps can also be harder to control (esp if not leaned correctly). To play it safe you should probably be around 12.5-13.0gph running rich of peak to run best power and maximum speed cruise. Big jump in fuel and cost for only a little more speed.

All climbs are full throttle, full rpm, lean mixture about every thousand feet to set them to what they usually read on takeoff at sea level. Climbing full power gets the climb over with faster. Power will steadily and continuously decrease to cruise power as you approach 8000ft. About 110-120kias in the climb keeps things cool and efficient. 

As you level off above 3000, leave the throttle full, reduce rpm to 2500 (2600 or 2700 if you’re high), and do the big pull where you swiftly move the mixture straight back to that 8 or 8.5gph. That’s the easy way of doing it and what i usually revert to if I’m busy. You can learn more about EGT, peak, lop, rop, etc as you progress but that’s the safe and easy way to do it.

[Shadrach]

4 hours ago, FastTex said:

Great, thanks. At what speed do you usually climb? I need to watch my oil temp which has the tendency to go to >210 easily but I can control it if I lower the RPMs...maybe staying at WOT can help? 

For standard ops I use take off flaps, trim and apply a few pounds of back pressure to the yoke. As soon as I have positive rate, I clean up the airplane, pitch for 120mias which almost always yields 1000fpm or more through about 4000msl. I  often decrease pitch for 500fpm and take whatever that yields. I lean for 1200ish on my leanest cylinder during climb. 

 

Edited October 25, 2018 by Shadrach

[Hank]

3 hours ago, carusoam said:

Mixture Topics to read up on...

0) lean on the ground to avoid build ups on the plugs.

1) LOP, fuel air ratio, CHT cooling...

2) Ignition timing what makes 25°BTDC desirable...

3) Leaning in the climb to altitude... blue/white box EGT methodology.

4) Target EGT for departures at higher altitudes than SL... and climbs to cruise altitude

5) lop can be used in all phases of flight, During cruise and descent has the most value, least risk...

6) old POHs gave advice to run 50°ROP and ignored LOP... these were funky pieces of advice at best...

7) CHT control is everything. <380°F is preferred by many...

8) avoiding The red box is very important.

9) high powered climb, target 120 to get a decent rate balanced with chts...

10) Gumps... make sure the mixture is in for go around...

bonus points...

11) Gami spread...

12) Savvy.com

13) learn how to post your engine monitor graphs.

 

PP thoughts only, not a mechanic...

Best regards,

-a-

I bolded the easy to do parts that will save money and headaches. Can't comment on LOP, as your injected engine does that much different [and easier!] than my carbureted one . . .

Have fun, learn lots and fly safe!

[FastTex]

On ‎10‎/‎25‎/‎2018 at 9:09 AM, 201er said:

As long as the compression ratio on F is same as J. I think it is but someone who has one should confirm.

8.0gph is 60% power at lean of peak. Very economical, cool, can’t hurt the engine no matter how you leaned to get there. Just not enough fuel to make enough power to do anything wrong. Going any slower doesn’t pay. This setting takes you just a little over Carson’s speed.

8.5gph is 65% power at lean of peak. Economic with a little more speed probably the best bang for the buck while still running cool.

10.0gph when lop makes 75% power but if you don’t lean correctly you could run into detonation or just be trashing your engine. Temps can also be harder to control (esp if not leaned correctly). To play it safe you should probably be around 12.5-13.0gph running rich of peak to run best power and maximum speed cruise. Big jump in fuel and cost for only a little more speed.

All climbs are full throttle, full rpm, lean mixture about every thousand feet to set them to what they usually read on takeoff at sea level. Climbing full power gets the climb over with faster. Power will steadily and continuously decrease to cruise power as you approach 8000ft. About 110-120kias in the climb keeps things cool and efficient. 

As you level off above 3000, leave the throttle full, reduce rpm to 2500 (2600 or 2700 if you’re high), and do the big pull where you swiftly move the mixture straight back to that 8 or 8.5gph. That’s the easy way of doing it and what i usually revert to if I’m busy. You can learn more about EGT, peak, lop, rop, etc as you progress but that’s the safe and easy way to do it.

So...this works great, THANKS! I have been doing a few flights where I quickly moved to about 8.5GPH. Everything appears to be more stable (oil temp, CHTs, etc.).

Now at what point to "revert"? For example: I like to be @pattern ALT when about 3NM from the airport. If I'm @5000' with WOT, 2400RPM and 8.5GPH how do I get to FULL PROP, MAX MIXTURE and LOW RPM/Speed and get ready to land? It might sounds like a silly question but I found myself to look for a procedure during that phase of the flight.

[jaylw314]

Most people are of the mind to simply descend without making any changes.  You'll go really fast during the descent and the air will make your mixture even more lean, so your CHT's should decrease some as you descend.  Once you're at pattern altitude, you just pull throttle, increase prop and mixture.

I often take a couple more steps because my wife hates bumps, so going fast down low is not always kosher.  I'll leave the mixture leaned, reduce throttle to about 19" MP and then reduce RPM to 1900 (MP will climb to about 20" or so).  I don't have a RPM restriction, so this wouldn't work for everyone.  That way, descent will be slower, and the slower RPM's will keep enough heat in the engine.

[Bob - S50]

It's all technique so you'll have to try a few things and decide what you like.  My descent plan:

If the air is smooth, just lower the nose and trim for 500 FPM rate of descent.

If there is even a suggestion that the air may be bumpy I leave my RPM at 2600, descend at 500 FPM and keep pulling the power to maintain 20" MP.  If that turns out to be too fast for the amount of turbulence, I'll use 15" MP instead.

Approaching the pattern I'll pull the power to 15", reduce RPM to about 2200 or 2300 and slow to about 100 - 110 KIAS.  At some point in the pattern my RPM will drop below my selected RPM.  That tells me the engine is not making enough power to allow the prop control to maintain RPM so I can safely push the prop control full forward.

During this entire time I never touch the mixture.  I leave it set from the time I set it for cruise until I shut down for parking.

If I have to go around I have trained myself to do the following:  cowl flaps open, mixture full rich, prop full forward, throttle full forward, positive rate, gear up, 80 KIAS, flaps up and run my electric trim nose down at the same time to compensate for the pitch change.  Then 100 KIAS, cowl flaps to trailing and climb at 100 KIAS to pattern altitude or 1000 AGL if executing an instrument missed approach.

Enjoy getting to know your airplane.