Mixture LOP vs ROP - Good video

[aero101]

http://www.aopa.org/members/files/pilot ... rrPpv_04Xm

[Island Flyer]

I saw this video a couple of days ago and was just going to ask some questions about others on the forum with LOP. There is also an article in the last AOPA Pilot magazine about LOP and ROP pros and cons that pairs with the video. Tim and I have discussed this several times in the past and from a mechanics viewpoint he thinks it could be good for his business because if you are off on the LOP parameters either from not having the proper engine monitoring equipment, or misreading the data, or the monitoring equipment not being accurate you can easily damage the engine. The ramifications of being a little off in ROP are mainly burning more fuel than you otherwise could get away with.

I've added the JPI EDM 700 so now I'll be able to monitor the engine. The fuel dispersal in the Lycoming is much better than a TCM so I haven't added GAMI injectors yet and may not need to. Tim recommends we run some tests once the plane is flying again and see if the CHTs between the cylinders is close enough before changing injectors or trying to run LOP. The attractive part is that it could save 2 or 3 gallons per hour and at $6+ per gallon that could be $20+ per hour.

Is anyone running LOP rountinely and what are your thoughts?

[BudG]

Hi Rhys,

glad all is coming along with your bird. Mine is getting ready to be covered so hopefully I'll have it back in a few weeks. Anyway to add to the thread. I have the IO540 and installed GAMI's. I too have the EDM700. When I initially got the injectors I ran the engine LOP on xcountries. I was at altitude and got about 110 mph indicated at about 9 gph. at 10-11K ft. running about 20deg LOP. Then I tried running at same altitude and if memory serves me, around 18" MP burning about 9-9.5 gph my indicated was 120mph. at 30 to 50deg ROP.
I was told to read my Lycoming owners manual and it said to run it ROP. I guess for the same reason alot of knowledgeable folks say run it ROP. I don't know about Cont.'s but it wasn't that much more fuel to stay in the safe zone. I regularly run about 50 ROP no matter what my flight profile. The EDM is great for that and CHT's for climbouts and operating in Eastern Washington. I'm no expert but for me an extra couple of bucks will just mean that I have to go without my frappacino ahahahaha.

PS. with the Gami's my cht's and egt's are almost flatlined and the engine purrs. Not that expensive all things considered.
Fuel at Whidbey Island is at $5.35 right now. Hope it holds.

CAVU2U
Bud

[SlowFlyer]

I have seen this subject all over the forum and the web. I find that the best info available about the subject is on the avweb articles http://www.avweb.com/news/pelican/182583-1.html (link is dedicated to cruise settings, read whole series for more info)
Having a carburated engine with less than perfect fuel distribution I stay on the very rich side of peak, 150F or more. If I had FI with GAMMI I would definetley run LOP, you get cooler cht, better fuel efficiency, less residues from combustion inside the cylinder leading to fouled plugs and other problems.
At high power settings 70-80% 50ROP should yield the highest cht´s (not good), still this is what engine manufacturer recommends.
Hope it helps.

[a64pilot]

The avweb article had me going, all the way up to where I can't lean more than 180 deg ROP.
OK so that's the magic that makes LOP work, don't allow ROP leaner than 180 ROP and you will get better fuel burns.
If you do what Lycoming recommends, and run 50 ROP, then you fuel consumption LOP or ROP won't be much if any different

[andy]

With an uncompensated carbureted O-360-C1F engine I stick with the instructions in the Textron Lycoming Engine Operator's Manual, which says at or below 75% power to lean for engine roughness and then enrich until the engine runs smoothly and power is regained. With an EGT gauge it says to operate at peak EGT for best fuel economy at 75% power and below. My JPI EDM-800 engine analyzer gives me a more accurate picture of peak EGT than the Maule gauge, which is only connected to one cylinder. The Lycoming Operator's Manual also says not to operate more than 150 degrees ROP at maximum (75%) cruise power unless the aircraft operator's manual shows otherwise and to monitor cylinder head temperatures.

With close cowling and no cowl flaps, Maule cylinder head temperature can be a problem in hot weather at low altitudes and slower airspeeds. I've watched the JPI CHT readings drop with a slightly richer mixture in that situation.

I've read the articles that favor LOP operations but all of them are for fuel injected engines. I also don't want to give the insurance company any reason to deny a claim by not following the manufacturer's recommended procedure.

[aero101]

As this video states and common sense dictates, LOP in carburated engine is not practical as it's not sufficiently balanced in EGT under most conditions. Even the fuel injected engines in most cases will require the Gami Injectors although Lycomings are somewhat better then Continentals in this respect.

[Mountain Doctor]

I have the JPI EDM700 and run my O-360 at peak at power settings below 75%. I monitor the CHTs and keep the hottest cylinder, usually #3, below 375 degrees and oil temp below 180.

If I start to run hotter, I will either lean it more into LOP (I can only do this slightly due to engine smoothness), or richen it to 100 ROP. 50 ROP creates too much heat and hotter CHT's than peak. So I run at peak, 100 ROP, or just barely LOP.

It works and is safe and effective. It's not rocket science but you need a monitor and you need to pay attention.

Not a big deal.

The Avweb articles are a good resource.