Question for Paul McBride, the General Aviation News engines expert: What is your professional opinion about flying a Mooney 20J with a Lycoming IO-360 engine lean of peak without fuel injectors if the temperatures are within guideline perimeters?
Paul’s Answer
This is a subject that has been around the general aviation community for a long time and it has always been a controversial topic. So, with that in mind, I’ll step off the cliff and give you my “professional opinion.”
Right out of the gate I’ll start off by saying that if it were my airplane and engine, I wouldn’t do it, and I’ll give you some reasons why.
Hopefully, anyone who is considering doing this during the operation of their Lycoming engine should first refer to Lycoming Service Instruction 1094D or its latest revision.
Probably the most important recommendation set forth in SI1094D is this statement in bold text: “ALL LEANING RECOMMENDATIONS ARE BASED ON CALIBRATED INSTRUMENTATION.”
Lycoming follows this statement by stating that the company also recommends “that all engine instrumentation be calibrated annually.”
Now I’ve been around the aviation community for a long time and I’ve got to be honest with you: I couldn’t tell you of one aircraft owner I’ve met over the years who has complied with that recommendation. How about you?
Another thing that really concerns me is that instrument calibration of the more sophisticated turbocharged engine is extremely important because of the higher operating temperatures.
While there are all kinds of products that claim better operational results — and there may be — I still am from the old school that subscribes to the aircraft and the engine manufacturers’ recommendations.
In my mind if these so-called improved operational products were that good, don’t you think the original manufacturer would be using them?
The one big question you must ask yourself is if these improved products are going to be suitable for safe operation across the board worldwide in some very different operational arenas than the one you operate in.
I’d also like you to think about one other thing: Is it worth it to operate your engine at lean of peak?
I think the two least expensive things you can put in your engine are avgas and oil.
If you don’t believe that, just ask someone who recently had to replace a cylinder.
LOL on the last two sentences.
What’s wrong with me…. I never lean while taxiing……and I always run Lean of Peak while flying…,,,,Lycoming O-320 fuel injected…….I even have a Lean Assist on my Dynon that tells me how much lean of peak I am running…..Engine runs like a Top and plugs are Super Clean….One thing that I Do Do is I run the Fine Wire plugs all on the bottom and regular plugs on top.
38 years Lycoming 0-360 LOP, no problems.
I go by what the engine says. As mentioned, Mfg. publications assume an inept pilot.
For the past 20 years, I have run my Continental IO 520 engine lean of peak. In the 784 hours since top overhaul with new cylinders, the only problem I have experienced is one exhaust valve not sealing completely . It was rectified about 4 years ago and no other problems. Oil consumption is about 1 quart per 5 hours. Lean of peak works for me on the Continental engine.
I would love to give you an answer. But I have not been flying regular. I was taught this when I first started. I don’t want to answer a Queston I am not sure of. Please get the info
from a pro. I hope you get the answer.
I’ve followed the Lycoming leaning recommendation on my TCM engine for the last 15 years. The engine runs clean; plugs are clean, cylinder borescope shows little build up on the heads , valve look great, exhaust stacks are a light gray.
The engine is close to TBO and uses only 1 qt of oil per 10-12 hours.
Fuel is actually my second highest expense, behind the hangar rent. !
How do you operate an IO-360 without fuel injectors???
Running lean of peak: During normal operation (rich of peak) means you are cooling the cylinders down from stoichiometric (peak temperature) with excess fuel. Running lean of peak is cooling the cylinders with air. Lycoming says not to operate lean of peak.
The engine is air cooled whether ROP or LOP. When ROP, the additional fuel HELPS with cooling. When LOP, the engine is making less power, which HELPS with cooling. Less power when LOP equals lower inter-cylinder pressure and contributes to engine longevity.
Lycoming recommendations have been well established as the MFG not trusting pilots to understand proper LOP operations, so they maintain that ROP is preferred. The fact is that running incorrectly ROP is more likely to cause damage (e.g. 50° ROP above 75% HP.
I’m wondering the same thing, along with what “products” Paul referred to in the article.
I’m wondering the same thing, along with what “products” Paul referred to in the article.
The only ‘operational product’ that I use is Camguard, along with Phillips 20-50xc oil.
Other add TCP to reduce the lead compounds build up in the engine.
leaning during taxiing keeps the plugs hot to reduce the lead deposits and fouling.
I lean at all altitudes during cruise, to the onset of roughness, then richen for smooth running.
I asked myself the same thing, an IO360 with no fuel injectors is not going to run well. Lol I assume he meant he doesn’t have balanced GAMI injectors, however the IO360 does not usually need them as it will typically run very well 50* LOP on the stock injectors which are balanced and matched out of the box. If you want to find out for sure if your engine will run LOP, you need to run the GAMI lean procedure on the Savvy website, record the data, upload it, and find out what the GAMI spread is between each cylinder. Ideally you want it under .5GPH.