Cessna Mag article "What you don't know about your engine can kill it" August 2003. Basicly they are saying lean to peak ... then a little further and she'll smooth out and run cooler. Keven Knight refered to constant speed engines, I have a variable speed Lycoming O-320-E2D in my 172M. I also have a single EGT prob on my #4.
Does this LOP 50 degrees apply to variable speed also? Has any one out there tried it on this engine?
I'll admit I'm a little nervous trying something that goes against all my previous training, but it does make sense. Before I try it, I'm curious if anyone else has, and the results they got.
I am one of the instructors Kevin Knight was writing about. Yes, I've tried it. Yes, it works. No it won't hurt your engine. Yes, it's better for it. I personally know several Cessna 150 and 172 owners who are operating this way. More 182, 185, 206, and 210 guys. You do need to know HOW and you do need the proper instrumentation and knowledge of what's happening in the engine. We are NOT a LOP school. We are an engine management school and we teach ROP operation safety as well.
We had 36 participants in this month's class (last weekend) and about 7 or 8 were Cessna owners. The rest were a mix of Beech, Piper, Lancair, and Cirrus. I don't think we had any Mooney drivers in this last class. The bulk were operating injected engines, but several were operating carbureted engines.
Visit our website to see what participants have been saying after they take the class.
Walter Atkinson
Advanced Pilot Seminars
www.advancedpilot.com
IF all of your F:A ratios are balanced, yes a single probe EGT works.
In a 172, this will not likely work well without better instrumentation.
Visit our website at www.advancedpilot.com and see John Deakin's articles on AVWEB at www.avweb.com under the moniker, Pelican's Perch. Read Kevin Knight's article in Cessna Owners.
I've been following with interest the various reactions to Kevin Knight's article on "leaning" in the August COO magazine. I'm curious to learn if Lycoming or TCM has responded to the article--does anyone have any information from the manufacturers? In the meantime, erring on the side of caution makes me want to abide by the POH in terms of leaning my 172M.
Cheers!Walter Atkinson wrote:
> IF all of your F:A ratios are balanced, yes a single probe EGT
> works.
>
> In a 172, this will not likely work well without better
> instrumentation.
>
> Visit our website at www.advancedpilot.com and see John
> Deakin's articles on AVWEB at www.avweb.com under the moniker,
> Pelican's Perch. Read Kevin Knight's article in Cessna Owners.
>
> Walter Atkinson
> Advanced Pilot Seminars
Interesting comment by one of your attendees: "After attending the Advanced Pilots' Seminar, I changed my technique to run at or slightly (50F) rich of peak EGTs at those altitudes... Since the class -- AT ALTITUDES > 8000 -- I have been doing exactly that (on normally aspirated IO470Ls) and there is no way to hurt the engines up high. ..." It doesn't sound like you've convinced HIM that LOP is a good idea!
Let me weigh in on this subject if you don't mind. John Deakin is a highly respected voice on this subject, and I find his opinions highly educational. But in order to take advantage of LOP (lean of peak) operations safely, it is a MUST that proper engine instrumentation be implemented,...ALONG WITH an engine set-up that can be usefully and safely managed with that instrumentation.
BOTTOM LINE: Single probe: There is NO WAY a horizontally opposed, air cooled, CARBURETED engine can be safely run lean of peak on more than a few cylinders, above 65% power. Period. The reason is that in order to do that, the sloppy system that involves a carb will have at least SOME cylinders running richer than that, and THAT means SOME cylinders are at risk of valve and piston failure. The only way to safely run carbureted engines is in accordance with their mfr recommendations, typically such as that of Continental, which state:
This will give best economy, best range (for that power setting), and safest running condition for the engine (at that power setting.)
No one should consider LOP operation without accurate EGT/CHT instrumentation on EACH CYLINDER regardless of fuel metering type.
"Constant speed engine" ??? "Variable speed engine" ??? Give it a rest. If such terminology is being thrown around by the clients then it should be pretty clear there's not much understanding going on or the subject is not being competently taught. (Sounds like we've got another "thermal runaway" going on.)
George... you stress CARBURETED. Can a fuel-injected IO-540 (182S) be run LOP safely? If so, under what conditions?
> BOTTOM LINE: Single probe: There is NO WAY a
> horizontally opposed, air cooled, CARBURETED
> engine can be safely run lean of peak on more than
> a few cylinders, above 65% power. Period. The
> reason is that in order to do that, the sloppy
> system that involves a carb will have at least
> SOME cylinders running richer than that, and THAT
> means SOME cylinders are at risk of valve and
> piston failure. The only way to safely run
> carbureted engines is in accordance with their mfr
> recommendations, typically such as that of
> Continental, which state:
> This will give best economy, best range (for
> that power setting), and safest running condition
> for the engine (at that power setting.)
> No one should consider LOP operation without
> accurate EGT/CHT instrumentation on EACH CYLINDER
> regardless of fuel metering type.
> "Constant speed engine" ??? "Variable speed
> engine" ??? Give it a rest. If such terminology
> is being thrown around by the clients then it
> should be pretty clear there's not much
> understanding going on or the subject is not being
> competently taught. (Sounds like we've got
> another "thermal runaway" going on.)
GAMI offers an advisory service concerning LOP operations with single probe EGT equipment.
Their Instructions-
1- Set up cruise at 5,000 to 7,000 feet, approx 65% power (or any power setting that keeps CHT below 400F), normal cruise RPM, and cowl flaps open if equipped.
2- Find "peak" on the EGT.
3- Determine if engine runs smooth at 50F LOP.
4- Call GAMI with your data @ (580) 436-4833, for consultation.
i have a 1970 172k 0320 e2d no egt no cht what is the safe leaning tecnique i fly from sea level to 3000' 5000' 8000'poh says lean til slight drop in rpm then slightly richin tail pipe inside color is white'ish am i safe using this method thanks mike
George Horn mentioned the best source of information out there...John Deakin's "Pelicans Perch". I have studied his articles about LOP engine managment. I installed GAMI injectors and 6 probe EGT/CHT in my 185 with the IO520 and flew LOP for several hundred hours. Two years ago in installed a factory reman IO550 and run it LOP.
My aircraft flies faster, runs cooler, smoother, and burns 20% less gas LOP. I have about 500 hours LOP between the two engines.
Typical CHT's are something like 345/342/350/352/348/345....usually less than a ten degree spread.
The 550 takes about 18gph to run ROP with CHT's in the high 370's....I gain 5mph and burn 14.5 LOP with CHT's as cited above.
Friend of mine flies a 185 and a 206 LOP with the same setup, probably has at least 1000 hrs between the two. Flies long trips, such as AK to Central America.
Another guy flies his turbo Bonanza from Anchorage to Hawaii (20 hours I'm guessing over the Pacific) LOP.
