How Do You/How Should I lean a O470

[Nikhiln25]

Pretext this by saying I’m a new plane owner and a 140 hour PPL. I own a Cessna 182R with O470U and JPI 730 with 6 point EGT/CHT probe.

My flight school taught me the old pull till power drop then add. I carried that with me until my current plane, for which now I just lean to loss of power, add back a bit until the plane doesn’t add anymore power and then just make sure CHTs are below 380 (this would correspond with peak egt operation I believe if I was to use lean find). My mechanic told me (correctly) that the POH says best power is for 65% less power only and I should do the 50 RoP. I usually run 22/22 or 22/23 mp/rpm regardless of altitude. If high then I’m full throttle.

This results in usually 70% power or around there. For this the PoH recommends 50 RoP. But everything I’ve heard about 50 RoP is it’s the worst place to operate, the red box etc etc. I want to make sure I’m not harming the engine at peak egt and 70% power

I know this will bring some opinions out, but how do you lean your 182s

 

[flyingron]

With a carbed engine, the flows aren't likely close enough to get all the cylinders to peak together, so even despite the multipoint engine gauge, you're still in the lean til it start to peak and then enrich a bit.

 

[GeorgeC]

previously:
https://www.pilotsofamerica.com/community/threads/poh-vs-engine-operators-manual.90376

 

[flyingron]

The 182R POH is somewhat vague here. None of the mixture settings are "limitations" other than "Run full rich below 8000 and then you 'may' lean out."

It does say if you have an EGT, you can lean to 50 rich of peak for "recommended lean" or peak for "best economy." Again that's going to have to be the "first peak" if you have a multipoint.

Continental says that as long as you are at (or below) max recommended cruise (which above 8000 in this N/A engine you will be), then you can set the mixture anywhere between full rich and so lean that the engine is misfiring and you won't harm anything.

 

[Nikhiln25]

The 182R POH is somewhat vague here. None of the mixture settings are "limitations" other than "Run full rich below 8000 and then you 'may' lean out."

It does say if you have an EGT, you can lean to 50 rich of peak for "recommended lean" or peak for "best economy." Again that's going to have to be the "first peak" if you have a multipoint.

Continental says that as long as you are at (or below) max recommended cruise (which above 8000 in this N/A engine you will be), then you can set the mixture anywhere between full rich and so lean that the engine is misfiring and you won't harm anything.

When they say max recommended cruise do they mean what the cruise table peaks out at (so 75%?) or 65%. I would think logically if I’m at 70%, not a single cylinder is above 370 with cowl flaps closed, and there is no engine roughness, does where I am on the EGT curve even matter? I would guess the answer is no

 

[flyingron]

For the O-470-U the max recommended curise is 172 BHP at 2400 RPM. If you work down from the rated HP of 230, that's pretty close to 75%.

 

[455 Bravo Uniform]

I think I’ve shared this on POA a few times. Apologies if you’ve already seen it.

 

[Nikhiln25]

I think I’ve shared this on POA a few times. Apologies if you’ve already seen it.

Thank you

So effectively less than 75% power (since that is the max recommended cruise for this plane va the 65% mentioned in the video above) my practice of pull till rpm loss, add to gain back power and watch CHT is sufficient enough without obsessing over where I am on EGt curve

 

[MountainDude]

You are doing just fine. I would not change anything.

 

[Ed Haywood]

Add the RPM, MP, FF, and OAT sensors to your JPI 730. Then it will calculate and display % HP for you. Use that to set cruise power, lean til it stumbles, enrich til smooth, and fine tune with the FF.

 

[Nikhiln25]

Add the RPM, MP, FF, and OAT sensors to your JPI 730. Then it will calculate and display % HP for you. Use that to set cruise power, lean til it stumbles, enrich til smooth, and fine tune with the FF.

Yup- I’m planning on making the full investment into the 730 in the coming months. Won’t cost me much relative to what it will give me

 

[Ed Haywood]

Yup- I’m planning on making the full investment into the 730 in the coming months. Won’t cost me much relative to what it will give me

I think that is a smart move. As a new owner, it will give you more confidence in learning to operate your engine at max efficiency. I think you'll like the added redundancy also.

 

[WDD]

Bringing an old thread back to life.

I have a 0 470R in my 182P. I've been experimenting running LOP. I pull mix back until stumble, add a bit, and then keep richening the mixture in increments to raise the CHT until it gets to 380. I'm effectively not managing by targeting a certain temp below or above peak EGT, but but rather by adjusting to hit the desired CHT. My reasoning is that it's the CHT that matters.

I've gone from 14 GPH to 11, and I can't see a decrease in TAS. In all fairness, I'm now flying in late fall cooler temps, so that might be affecting it.

Nothing bad has happened so far; no cylinder heads departing, no drastic (or any for that matter) increase in oil consumption, etc.

 

[asicer]

I have a 0 470R in my 182P. I've been experimenting running LOP. I pull mix back until stumble, add a bit, and then keep richening the mixture in increments to raise the CHT until it gets to 380. I'm effectively not managing by targeting a certain temp below or above peak EGT, but but rather by adjusting to hit the desired CHT. My reasoning is that it's the CHT that matters.

What are the other 5 CHT? The differential also matters.

 

[WDD]

What are the other 5 CHT? The differential also matters.

True. I only have a simple single CHT / EGR instrument. I do need a more modern EIS.

 

[RyanB]

Bringing an old thread back to life.

I have a 0 470R in my 182P. I've been experimenting running LOP. I pull mix back until stumble, add a bit, and then keep richening the mixture in increments to raise the CHT until it gets to 380. I'm effectively not managing by targeting a certain temp below or above peak EGT, but but rather by adjusting to hit the desired CHT. My reasoning is that it's the CHT that matters.

I've gone from 14 GPH to 11, and I can't see a decrease in TAS. In all fairness, I'm now flying in late fall cooler temps, so that might be affecting it.

Nothing bad has happened so far; no cylinder heads departing, no drastic (or any for that matter) increase in oil consumption, etc.

Get ready to put cylinders on it. You aren’t doing yourself any favors running LOP. Those few dollars saved in fuel will be ready to spend on new cylinders.

 

[Ed Haywood]

Bringing an old thread back to life.

I have a 0 470R in my 182P. I've been experimenting running LOP. I pull mix back until stumble, add a bit, and then keep richening the mixture in increments to raise the CHT until it gets to 380. I'm effectively not managing by targeting a certain temp below or above peak EGT, but but rather by adjusting to hit the desired CHT. My reasoning is that it's the CHT that matters.

I've gone from 14 GPH to 11, and I can't see a decrease in TAS. In all fairness, I'm now flying in late fall cooler temps, so that might be affecting it.

Nothing bad has happened so far; no cylinder heads departing, no drastic (or any for that matter) increase in oil consumption, etc.

Hard to know for sure given lack of instrumentation, but I would guess your method is closer to peak EGT than LOP. I dunno what Conti says, but Lyco says peak EGT for best economy is just fine.

 

[Brad Z]

True. I only have a simple single CHT / EGR instrument. I do need a more modern EIS.

LOP is very difficult with a carbureted engine due to uneven fuel dispersion, and impossible without a 6 cylinder EGT sensor to monitor the EGT delta of each cylinder.

 

[Randomskylane]

Lean to fuel flow per book, then watch cht. It’s quicker than lean to stumble and guess a turn/ half turn/ quarter turn/ whatever you are doing

 

[danhagan]

I did the same as you in my previous Tiger. Spent several minutes watching which cylinder was reaching peak adjusting, fine tuning ... then just went with the pull mixture to stumble and add 2 turns ... it was the same place on my plane (carbed also). Probably read the same things you're looking at as a new owner as well regarding 50* ROP, etc.

Ran that Tiger for over 11 years and about 1000 hours. It was at 1700 total time when sold and they did a thorough inspection for the new buyer including the "valve wobble test" ... awesome compressions and passed that wobble test with flying colors ... so I guess the old technique leaning works well. That plane has had 3 more owners in the past 6 years and still hasn't had an engine overhaul ...

 

[MRC01]

With a carbed engine, the flows aren't likely close enough to get all the cylinders to peak together, so even despite the multipoint engine gauge, you're still in the lean til it start to peak and then enrich a bit.

True. Yet some engines get closer than others. One factor (among several) is the intake runners. Engines having the carburetor near the center have intake runners that are closer to equal length, and consequently more even mixture distribution. Engines having the carburetor located near one end of the engine (front or back), have unequal length manifold runners which contributes to bigger differences from leanest to richest cylinder.