too aggressive leaning?

[dominikos]

I’m new to leaning, as I used to follow POH using a single EGT gauge. Now, with a new engine monitor, I’m trying to figure out the proper approach. I attached screenshot of my engine monitor from today’s flight. Here is my logic for leaning:

• I try to stay below 65%, as somebody noticed, above 8,000 ft, 65% or less is a norm anyway
• I keep CHTs at/below 380F. If needed, I open cowl flaps slightly. #1 cylinder is the warmest
• EGTs, watch them but don’t really use for leaning - try to keep them below 1500F
• I lean for smooth performance, lean out, find rough running engine, and come back from there

Plane is M20J. Am I too aggressive? On this flight, at 6,000ft, power was at 47%, TAS: 131kts (with 35kts XW), fuel flow @ 6.3 gph.

[kortopates]

Below 65% power you can leave the mixture anywhere without concern. There is no longer a red box of high ICP’s to avoid. If not in a hurry, just lean a bit past peak on the LOP side to get maximum NM/GPH for max economy and cool temps if you like.


Sent from my iPhone using Tapatalk

[Fly Boomer]

16 minutes ago, dominikos said:

I keep CHTs at/below 380F.

With those CHTs, I think you are fine.

[Ragsf15e]

Honestly if you’re below 65%, then play around because you won’t hurt anything.  Start with say wide open throttle, 2500rpm, and 8000’ cruise.  Lean back very slowly until the last cylinder peaks.  You can leave it right there at “peak” if you like.  If you want a smidge cooler cylinders, lean 10 degrees further on that last cylinder.  Beyond that at low power, you’re losing lots of speed for not much gain in efficiency.  

[mhrivnak]

These engines can often go deeply lean of peak before getting rough. When I do Savvy's GAMI lean test, it'll go down to 90F LOP before any significant roughness. You certainly can fly deeply LOP, but you might consider being much closer to peak to get the LOP benefits while still keeping most of the speed. I usually aim for ~25F LOP.

FWIW those CHTs are a lot higher than I'd expect to see on my J at such a low power setting. Same for oil temp. May be wise to check the baffling next time the cowling is off. Though I usually fly at around 130Kts indicated, and maybe the extra air flow more than offsets heat from the additional power?

[Ragsf15e]

8 minutes ago, mhrivnak said:

These engines can often go deeply lean of peak before getting rough. When I do Savvy's GAMI lean test, it'll go down to 90F LOP before any significant roughness. You certainly can fly deeply LOP, but you might consider being much closer to peak to get the LOP benefits while still keeping most of the speed. I usually aim for ~25F LOP.

FWIW those CHTs are a lot higher than I'd expect to see on my J at such a low power setting. Same for oil temp. May be wise to check the baffling next time the cowling is off. Though I usually fly at around 130Kts indicated, and maybe the extra air flow more than offsets heat from the additional power?

72 degrees F oat probably didn’t help his chts either.  But you’re right, more speed generally helps the cooling.

[Schllc]

I only have experience with the big continental mooney's but LOP always yielded temperatures much lower.  Average LOP would be closer to 320degF

ROP would be at those temps averaging closer to the 365deg.

Are these temps typical for the four cylinder LOP?

[Ragsf15e]

10 minutes ago, Schllc said:

I only have experience with the big continental mooney's but LOP always yielded temperatures much lower.  Average LOP would be closer to 320degF

ROP would be at those temps averaging closer to the 365deg.

Are these temps typical for the four cylinder LOP?

No, I’ve always seen low 300s, but in that picture he’s at low altitude with throttle pulled back to help get to low power.  The oat is pretty warm.

Up at normal cruise altitudes with wide open throttle and barely lop he should see low 300s.

[Mooney Dog]

wow i have never seen my CHTs that hot in my E model down here. I normal sit around 320-330 on all of them, 14xx egt. Recent temps too. Didnt think speed would play that much difference.

 

Granted i normally run ROP around 9.8gph.  

From Lycoming website as well

""During normal operation, maintain the following recommended temperature limits:

• Cylinder head temperature – limit listed in the Lycoming Operator’s Manual.
• Oil temperature – limit listed in the Lycoming Operator’s Manual.
• For maximum service life, maintain the following recommended limits for continuous cruise operation:
• Engine power setting – 65% of rated or less.
• Cylinder head temperatures – 400˚ F. or below.
• Oil temperature – 165˚ F. – 220˚ F.

""

Edited May 21, 2022 by Mooney Dog

[Cruiser]

you seem to understand the process. You hit all the key data points. Your procedure seems fine. 

For normal operation, you were way too LOP, there is no reason to operate that far LOP unless you just want to save fuel and are not in a hurry to go anywhere. 
65% HP would be 8.6 gph FF. You can experiment with the settings but anything above 5000' AGL you should be full power and lower RPM to set the desired performance. 

Monitor the CHT, EGT and FF as you are doing. 

[mooneyflyfast]

Those CHTs are fine and typical in my experience. Under these conditions I would typically run full throtle 2500 RPMs. IAS 130. TAS 150 burning 9 GPH.  if 3 or 4 CHT gets close to 400 lean very slowly while monitoring CHT. If you lean too much your speed will suffer. There’s a sweet spot where yourCHTs are good and your speed doesn’t suffer unduly.  Your low power setting/130 TAS would be fine for just puttering around but would be torture on a long cross country.

[dominikos]

appreciate everybody pitching in, good to have validation that I’m approaching it correctly. The purpose of the flight was just a quick hop to drop plane for annual. I would try to go a bit faster on x-country.  50 kts winds were not helpful in getting anywhere fast…

[Shadrach]

+1 for oddly high CHTs for the fuel flow/power setting.  I don’t see CHTs that high in full power climb, but perhaps it’s a function of how slow you are flying in warm air.  

[Ragsf15e]

Here’s what mine looks like at similar power… wide open throttle, just LOP (like 10 degrees), 9500’.  My outside temp is much cooler and in celcius.  Outside temp makes a big difference in my experience.  My chts are much lower than yours.  My number 1 has always been cool.

This had my F settle out around 141 ktas loaded about 300lbs below gross.

 

 

[jaylw314]

3 hours ago, Ragsf15e said:

Here’s what mine looks like at similar power… wide open throttle, just LOP (like 10 degrees), 9500’.  My outside temp is much cooler and in celcius.  Outside temp makes a big difference in my experience.  My chts are much lower than yours.  My number 1 has always been cool.

This had my F settle out around 141 ktas loaded about 300lbs below gross.

 

 

 

I don't think colder air at altitude is as helpful as you think.  The delta T between a CHT of 350F and OAT of 10F is 340F, while at OAT of 70F the delta T is 280F.  I mean it is a bigger delta T, but not by a massive amount. 

Worse still, at altitude, the air mass is 30% less at 10,000' MSL, so it's ability to cool is nerfed right there, even if the air is colder.

Cruising in my J over the SoCal desert during the summer, I would get OAT's of 75F at 10,000' MSL.  That was not fun when ATC asked me for higher, and I typically would see CHT's in the 380-400F range, which is really the only time I ever do.  At home in the NW during the summer, I'll cruise at 5,000' MSL at 75F, but my CHT's are comfortably down in the 330-350F range.

Edited May 23, 2022 by jaylw314

[Ragsf15e]

17 minutes ago, jaylw314 said:

I don't think colder air at altitude is as helpful as you think.  The delta T between a CHT of 350F and OAT of 10F is 340F, while at OAT of 70F the delta T is 280F.  I mean it is a bigger delta T, but not by a massive amount. 

Worse still, at altitude, the air mass is 30% less at 10,000' MSL, so it's ability to cool is nerfed right there, even if the air is colder.

Cruising in my J over the SoCal desert during the summer, I would get OAT's of 75F at 10,000' MSL.  That was not fun when ATC asked me for higher, and I typically would see CHT's in the 380-400F range, which is really the only time I ever do.  At home in the NW during the summer, I'll cruise at 5,000' MSL at 75F, but my CHT's are comfortably down in the 330-350F range.

I agree with the higher, less dense air not cooling as well.  I do think the outside air temp plays a descent role.  Even if it’s minor (say half the actual delta), it might be the difference between 380 and 350 CHTs.