LOP, Worth it?
 

Most people are trained to fly with the mixture set Rich Of Peak, but lately with fuel prices out of control there has been a lot of hype building about flying the airplane Lean of Peak. The advantage is your flying with much more efficient fuel burn, but your also running your engine hotter which could be damaging.

I learned about it in an engine class at the beginning of summer and towards the end of summer there was an article in AOPA that basically said it was the greatest thing ever, which made me interested.

Has anyone here ever experimented with it, or have any thing worth adding to what I've already said?

When I used to rent unless I needed to meet a specific time limit for a XX hour cross country or get to XX hours for XX certificate it was rental power all the way.
If you are paying for the aircraft wet and paying a common fuel surcharge the less you fly the less you pay so I flew just under redline everywhere I went and monitored the instruments to ensure I did not redline the tach or overtemp the engine.

The problem with LOP is you are operating very close to TOO lean, which would damage the engine.

The problem with using typical EGT's or just using the tach to set LOP is that the individual cylinders may not be (and probably are not) tuned identically in a typical engine. The EGT and tach look at the engine as a whole. You could have three cyclinders working ROP, with one cyclinder operating WAY too lean and the EGT will average the four and show you in an acceptablr range. Unfortunately, three cyclinders are burning more gas than you think, and one is getting cooked.

You might be able to operate LOP with a single EGT if your engine is tuned very precisely and you are confident that it will stay that way, but the accepted way to do LOP is to use seperate EGT/CHT sensors for EACH cyclinder...that way you can set LOP, monitor all cyclinders individually, and make sure that no one cyclinder is too lean.

Rental = go with ROP.

I agree with every one else if you renting then run rich, your paying for the fuel any way might as well burn it. If you own the plane then use lop to save if fuel.

Rich of peak. A touch more expensive, yes, but I think its the smart and safe way to do things. And if you rent, then its no matter.

All the airplanes here are generally are equipped with cylinder head temperature gauges with a redline that is reasonably accurate though usually not calibrated to Fahrenheit/Celcius scales with any accuracy. Since a cheap CHT gauge is connected to a single-point sensor, the sensor is placed at the point of highest expected temperature on the engine. On the lower left rearmost cylinder of an opposed Lycoming or Continental engine the highest heat is experienced due to poor exposure to intake cooling air flow around the engine. CHT, if it works properly is a more significant reference to engine temperature therefore. It is always prudent use oil temperature as a cross reference with both readings.

The latest fuel injected piston Lycos and Conts have individual LED readouts for EGT and CHT, as well as single-point oil temperature readings. These engines employ fairly sophisticated algorithms to advise the pilot when to stop leaning the engine based on a variety of considerations. The advisory system is very effective at balancing fuel consumption, cylinder head temp, oil temp and a variety of additional concerns such as engine life optimization.

On the other hand, if you are renting as others have said who cares, run it rich of peak. The waste of gas and added carbonization are minor concerns compared to burning a valve or cracking a head if you lean it out too much.

I read an article about operating LOP, but the guys had done quite a bit of aftermarket upgrades. They had a pretty nice engine analyzer installed, and most importantly an upgraded injection system to provide the correct amount of fuel to each cylinder. I'd advise that if you want to operate lean, talk to a mechanic who is open to the idea, and knows what you need to get the job done.

Running a typical NA engine slightly ROP is not exactly good for it. If you notice a good CHT gauge will actually show ROP running the hottest point (usually 50 ROP will yield peak CHT). EGT isn't the best indicator for wear upon the engine.... and some engines that run LOP don't quite evenly distribute the fuel/air to each cylinder either. LOP does not run hotter... CHT and ICP (pressure) starts to fall drastically... detonation is almost impossible LOP... however possible slightly ROP....ICP is an important bit of information often overlooked...especially in certain MP/RPM settings

There are a lot of myths in the aviation world... shock cooling is not as common as people think it is... (in order to shock cool an temps must drop around 500-600 degrees in a small amount of time) - Bob Hoover has feathered both engines in a redline dive and yet never had "cylinder head cracks"... go figure...

GAMI swears by LOP....

John Deakin talks quite a bit of running Lean of Peak (LOP). Here is his first column on it. There are several more in the archive section.
Pelican's Perch #8:<br>Go Ahead, Abuse Your Engine!

You'll need an account on avweb, which is free.

I ran LOP in a turbo normalized bonanza with an IO-550. We'd run props high, at 29" all day long, burning 17gps with a TAS of around 190kts. Never had any problems with the engine. But we had GAMIs and a digital engine trend monitor.

For time building:

Rather than chance long term engine damage by running balls to the wall and lean of peak, would you consider running at 55 to 65 % max power, normal mixture procedures and negotiate a dry rental rate with the FBO?