LOP?

[RBD]

My father-in-law recently purchased a Diamond DA40, which is equipped with the Garmin G1000 avionics package. He has owned several planes over the years, but none have had such detailed engine monitoring. I know that it is becoming more commonplace to run LOP and I've even heard that it is better for the engine. I'm looking for a good explanation of the logic behind LOP, as well as the pros and cons. Thanks for your help and I hope to see all of your beautiful RVs at Sun'n'Fun....please don't get mad if I drool on your canopy.

Cliff notes: Looking for info on LOP procedures, pros/cons.

[Bryan Wood]

Go to www.avweb.com and search John Deacon's articles called the Pelicans Perch. Somewhere in the mountain of good info there will be articles on LOP. Be aware that Deacon will be a new hero of yours.

Enjoy,

[petehowell]

Slight spelling correction on the name - but full agreement - the articles are great stuff

[airguy]

Agreed - very few people can explain LOP better than he already has.

[frankh]

An easy way to get there (sorry if this is so obvious...It wasn't to me until I'd flown for a while) is to simply yank the mixture until the engine basically quits and then feed it in a little at a time until the engine just runs smooth.

Check your CHTs they should be around the 295 to 325 range.

If you have a Dynon or similar you can select the lean mode and gradualy richen the mixture from here to find peak EGT and then back off to 50 to 100F LOP.

There are two reasons I do it this way.

1) the engine spends zero time in the 25 to 75deg ROP detonation danger zone.

2) The airplane is too fast for a novice IFR student and I wanted a way to tame the beast (slow it down) and get it set up quickly to a point where I didn't have to fuss with the engine, i.e concentrat on flying and not fussing with the red knob.

My IFR training protocol is to take off, set 2600rpm at 500 feet. At 2500ft (aiming for a cruise alt of 3000) pull the throttle to 20.5 to 21"MP, Dial the prop to 2400RPM. Pull the mixture for a quick and dirty smooth running as described above....This gives me around 100F LOP.

For my long cross county trip I will try to dial it in to 25F LOP, but I have a warm #4 cylinder which may prevent this.

Cheers

Frank

[Walter Atkinson]

The advantages of LOP operation include:
1) a cleaner running combustion chamber, cleaner ring lands, valves, and piston heads;
2) a cooler running cylinder, resulting in a stronger cylinder;
3) lower peak pressure pulses on the crank, bearings and lower end;
4) cleaner oil due to lower blow-by;
5) extended range, resulting in greater options when dealing with weather or ATC or changes in plans;

Cleaner and cooler are better. LOP is cleaner and cooler.

The only disadvantage is that you need to have a conforming engine where:
1) fuel:air ratios are balanced,
2) there is a healthy ignition system, and
3) there are no induction leaks.

But, you want that anyway, don't you?

Walter

[gmcjetpilot]

Originally Posted by Walter Atkinson

The advantages of LOP operation include:But, you want that anyway, don't you? Walter

Nice article in kit plane. I like your MESSAGE. It is reasonable and "balanced" with out hyperbole and rhetoric. Just the facts and opinion stated with out prejudice to others opinions. Nice job. Its a choice and not a must.

[kentb]

I now have 40 tach hour on my engine. I have been running 100 ROP even when running my engine below 75% power. My oil usage for the last 30 hours has been about 2 qts. I will be doing an oil change to regular oil (not mineral oil).

Should I continue to keep thing on the rich side or should I start using LOP operation now? Should I just try to put it at peak egt for now?

Kent

[frankh]

If you have been running your engine hard and the CHTS have been coming down (and possibly oil temp) then it has probably broken in.

If so I would go for it...If not then run it real hard (like WOT throttle down low) for another couple of hours and then run LOP.

Frank

[dan]

Originally Posted by kentb

Should I continue to keep thing on the rich side or should I start using LOP operation now? Should I just try to put it at peak egt for now?

Imho, you should first determine what the "gami spread" is for your engine (delta in fuel flow at peak EGT for all 4 cyls). Record the data if you can. If that looks good, i.e. the spread is down to a few tenths of gph or less, then imho you can have at it with LOP. If you have a wide gami spread, then you may want to invest in some custom restrictors for your injectors to achieve a lower (ideally zero) spread.