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Leaning for cruise, richening for climb

rightrudder

Well Known Member
So, I've got about 70 hours on my IO-320-D1A and am comfortable with 50 degrees LOP for cruise. I'm set up with EGT and CHT monitoring for all four cylinders.

So if I want to depart lean cruise and do a full-throttle climb, what's the best procedure? If I was at 4500' DA climbing to 6500' DA, I'd go full rich, floor it, and then re-lean at my new altitude. But what if I'm at 8500' DA going to 10,500' DA with the same climb scenario? In this case, would I just richen the mixture to, say, 150 degrees ROP? Full rich here and it would be gargling in fuel. I'm interested to hear your techniques.
 
I believe a link was recently posted here to a Mike Busch article about the "red box" or similar. Essentially, depending on your % power you need to be farther either ROP or LOP to avoid the highest internal cylinder pressures (ICP) that stress the engine the most. I actually downloaded the article and added it to my folder of engine manuals. I may even print out the graph and tape it to the panel. I'm on my phone other wise I would find and post the link.

Edit: https://www.jpinstruments.com/wp-content/uploads/2013/05/Mike-Bush-Red-BoxRed-Fin.pdf Here ya go, good reading

Chris
 
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Leaning for climb

I agree with previous posts. Additionally, your CHT's are a good indicator of internal combustion pressure. Keep CHT under control, and your engine will stay happy. Above 8000 DA, I cruise climb at full throttle by adding a bit of mixture to increase LOP EGT, or max climb by quickly adding a lot of mixture to about 150 ROP. In either case, I fine tune mixture to keep CHT between 360 and 380, depending on OAT. On hot days with heavy load, LOP climbing is not be feasible with my set up.

This is my first plane with full engine instrumentation, and I am impressed by how quickly CHT's respond to control inputs. In this case the analyzer supports the old rule of thumb "Never lean at full throttle below 5000' DA"

Jay
 
Thanks, guys. I appreciate the help! I always try to do the "big pull" quickly to get through the potential detonation zone.
 
In this case the analyzer supports the old rule of thumb "Never lean at full throttle below 5000' DA"

I assume you run full rich down low as a method of keeping CHT under control. You can lean to best power at any altitude, if you can cool the resulting output.
 
Good reminder Dan. I do use full rich at full throttle down low. My home airport is 3400' so I spend a lot of time above 5000', and sometimes forget others live at a more hospitable altitude.
Jay
 
Mixture in climb

Hi Doug,

I go from LOP in the cruise to my 'target EGT' for any climb, which ends up around 100 ROP above about 5,000'. My target EGT is what I get at sea level with WOT, 2500 RPM and full Rich (1200F). I always cruise WOT so its just a mixture change for me. When I get to the new altitude I let the aircraft accelerate ROP then re-lean for 25-50F LOP.
Cheers
Nigel
 
Target EGT

Hi Doug,

I go from LOP in the cruise to my 'target EGT' for any climb, which ends up around 100 ROP above about 5,000'. My target EGT is what I get at sea level with WOT, 2500 RPM and full Rich (1200F). I always cruise WOT so its just a mixture change for me. When I get to the new altitude I let the aircraft accelerate ROP then re-lean for 25-50F LOP.
Cheers
Nigel

Nigel is giving the best answer, IMHO. That terminology comes from the GAMI bunch. I have my target EGT pasted on my panel right next to my EFIS screen. I don't recall if he's using the method of determining the target EGT that they recommend but the important point is that you can lean for improved power during a climb and also improve fuel economy during it.
 
Hi Doug,

I go from LOP in the cruise to my 'target EGT' for any climb, which ends up around 100 ROP above about 5,000'. My target EGT is what I get at sea level with WOT, 2500 RPM and full Rich (1200F). I always cruise WOT so its just a mixture change for me. When I get to the new altitude I let the aircraft accelerate ROP then re-lean for 25-50F LOP.
Cheers
Nigel

Same procedure here, works fine.
 
Nigel is giving the best answer, IMHO. That terminology comes from the GAMI bunch. I have my target EGT pasted on my panel right next to my EFIS screen. I don't recall if he's using the method of determining the target EGT that they recommend but the important point is that you can lean for improved power during a climb and also improve fuel economy during it.

Same procedure here, works fine.
Aw, yes but please confirm for me that all of you are flying behind constant speed props. That is an important detail that needs to be included in the discussion. These numbers will be different flying behind constant speed and running LOP vs fixed pitch and running LOP.
 
I assume you run full rich down low as a method of keeping CHT under control. You can lean to best power at any altitude, if you can cool the resulting output.

I fly by CHT. Meaning that if I I add power and trim for climb, I may see my CHT's go up. Remember, as you climb the air will (should) get thinner, which macks your mixture richer. If my CHT's start to climb, I will add a little fuel to cool them.

Often I set ghe AP for a 500 FPM cruise climb and only lean when I hit my target altitude. If I'm going up a long way (more than 2,000'), I will add throttle as as go.
 
Const speed prop on 71NS

My 8 has a constant speed prop. The RPM does affect the EGT so if you are using a target EGT then there has to be a corresponding RPM value. For me it is 2500 RPM with the mixture full rich.

Bill you add throttle in a climb? Do you pull it back after takeoff? I guess I am lazy and just leave it firewalled all the time.

Cheers
Nige
 
Aw, yes but please confirm for me that all of you are flying behind constant speed props. That is an important detail that needs to be included in the discussion. These numbers will be different flying behind constant speed and running LOP vs fixed pitch and running LOP.

Yes, I'm running constant-speed.
 
My 8 has a constant speed prop. The RPM does affect the EGT so if you are using a target EGT then there has to be a corresponding RPM value. For me it is 2500 RPM with the mixture full rich.

Bill you add throttle in a climb? Do you pull it back after takeoff? I guess I am lazy and just leave it firewalled all the time.

Cheers
Nige

Yes, I'm running constant-speed.
Thanks for confirming that. Just so that anyone reading will know. The procedures and/or numbers for running with constant speed props will not be the same for those running fixed pitched props. As an example I have a fixed pitch with an IO-340. The above mentioned 2500 RPM is not attainable except for a small window of operation with my configuration. So if one is running fixed pitched and trying to mimic those numbers it will only be attainable in that small environmental window for which that prop/engine combination is designed.
 
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