LOP

[N57039]

Might as well get this one started early. How many fly LOP as a normal practice. I am one. I have no problem running LOP until the engine just about quits with the stock injectors in my IO360A3B6D.

[TurboExec]

I run LOP with stock injectors. IO360A1A.  I can take it all the way to cutoff with out a shake.  Burn less gas, lower temps, and a cleaner engine...what could be better.

[mooniac58]

Should this be attempted without an engine analyzer?   I was under the impression that you should have temps for all 4 cylinders/exhaust before trying this.  Is that accurate?

I would like to start messing around with this but I fear that one of my unmonitored cylinders will fall into a dangerous temp range...

[TurboExec]

No it is actually the other way around.  When running ROP one should have an engine monitor.  When LOP your engine doesn't shake you know that the fuel distribution is very good and thus all cylinders will be running close to the same power/temp/ICPs.  LOP actually results in lower tempatures and Peak pressures in the cylinder.  My CHTs run @ about 390dF when 150dF ROP, when I go 75dF LOP my CHTs drop to about 300dF.

Start Reading

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http://www.avweb.com/news/pelican/182085-1.html

 

[Magnum]

Hi all!

Maybe I am the only one, but I fly my 205 peak EGT. I tried LOP and it runs smoothly, but for me peak EGT is the best trade off between power and fuel consumption. I usually fly at 65%, above that I go 100dF ROP. I programmed the maximum CHT at 380dF on my EDM800, when I reach this temperature I open the cowl flaps a bit to keep the temperatures below.

Lycoming recommends peak EGT as economy cruise below 75% and prohibits LOP operations (source: Lycoming operators manual, PN 60297-12). I've read all the discussions with Walter on the AOPA forum and think he is right with ICPs. But: If you fly LOP you have unburned oxygen in the cylinders. And this can lead to burned valves and damage to the exhaust system.

I don't want to convince anyone to not fly LOP, IMHO everybody has to make his own decision. 

Magnus

[TurboExec]

Can you elaborate on why you think it will lead to burned valves and other exhaust problems...

[Magnum]

Quote: TurboExec

Can you elaborate on why you think it will lead to burned valves and other exhaust problems...

[TurboExec]

Quote: Magnum

If you have debris in the cylinder (eg. burned oil coal) at high temperature and oxygen flows over it, it starts to glow. And this can burn the valves. Disclaimer: This is just my opinion, I don't have data to proof it.

What differents shops report is higher wear on the exhaust systems. But the big questions is if it costs more than the fuel savings..

[Greg_D]

Quote: Magnum

If you have debris in the cylinder (eg. burned oil coal) at high temperature and oxygen flows over it, it starts to glow. And this can burn the valves. Disclaimer: This is just my opinion, I don't have data to proof it.

What differents shops report is higher wear on the exhaust systems. But the big questions is if it costs more than the fuel savings...

 

Magnus 

[N57039]

Magnus, With the gas prices in Germany I am surprised that you are not a LOP operator. Have you ever flown in a Mooney operated LOP? I'm guessing not because the fuel saving and lower CHT's with almost no airspeed loss are very real. Your NA engine would be very happy LOP. Please ask the shops that "report higher wear on the exhast systems" what they mean and by what chemical or mechanical mechanism LOP operation causes the alleged higher wear. Bet you cannot get a straight answer.

[Magnum]

I tried LOP and the engine ran fine to approx. 60dF LOP. I ran it at approx. 10-15dF LOP for some time, but now I use peak EGT. Why? I just feel more comfortable with it and I don't have the power loss when going on the lean side. I usually fly at 65% and use around 9-9.2 gal/hr. CHT's at 350-360dF, sometimes I have to open the cowl flaps for a inch to keep them there.

Just understand me right: I don't have anything against LOP operations, it is cooler and cleaner for the engine. IMHO peak EGT is the best compromise.

Magnus

[Magnum]

Quote: Greg_D

If you have debris in the cylinder (eg. burned oil coal) at high temperature and oxygen flows over it, it starts to glow. And this can burn the valves. Disclaimer: This is just my opinion, I don't have data to proof it.

What differents shops report is higher wear on the exhaust systems. But the big questions is if it costs more than the fuel savings...

 

Magnus 

[KSMooniac]

Another 100% LOP operator here with stock injectors on my IO-360 A3B6D.  If really high (like above 11k) I'll fly at peak, though.

[Magnum]

Why do you fly peak above 11k? Because of the power reduction when operating LOP? Just looked it up in the Lycoming manual, operating peak means about 4% power reduction, LOP about 8%. (Compared to 100dF ROP)

[KSMooniac]

Magnus, yes for the increased power.  When flying really high (like 15k-16k) I've gone to best power as well since there isn't much to make at those altitudes.  My typical cruise altitudes in the plains of the US are 7-9k, and I'll fly 10-40 dF LOP depending on OAT to keep my CHTs below 380dF.

[Magnum]

What "real" performance can I expect at FL140-150? The Lycoming manual says 58-61% (@ max RPM), that sounds a bit high to me. I've never been above FL100 (in Germany Class C airspace starts @FL100 and they don't really like VFR traffic up there) and my Instructor told me I'd get around 14-15", that'd be around 45%. What climb rates can I expect in a J at 2500-2600lbs gross weight?

[KSMooniac]

At 16k I was only pulling ~16" MAP, and TAS ~130 KTAS at 7 GPH or so.  Not much performance, but that was the MEA over the Rocky Mountains so there wasn't any better option.  Climb rates were down to ~200 FPM or so and this was at ~2300 lbs.  I think the book service ceiling is about 18k, and I've been up to 16.5k on a warmish day where the density altitude was over 18k, but I was nowhere near max gross weight either.  I don't think a J could get to 18k at gross very easily! 

[Magnum]

Thanks for the info, I won't top the tanks when I try it the first time.

[AustinKalb]

My MSC said not to run LOP until my IO550 has at least 100 hours on it. I'm halfway there. Any opinions on this?

Thx.

[TurboExec]

I have heard that it is ok to break in LOP and that it is bad....take your pick.  I fly my IO360 (lycoming) LOP after the first 25 hours.  It has about 80 hours on it now and at annual the mechanic commented on how clean it was and the great compressions....so LOP hasn't hurt it.

[KSMooniac]

LOP breakin is just fine.  I think it is most important to keep the power up and steady...ie XC cruise at 75% (or more) for the first 8-10 hours.  Walter Atkinson has posted the APS breakin procedure on the AOPA Forum a few times...might be worth searching over there if you're a member. 

[N57039]

Austin, At 50 hours your engine is broken in. Fly LOP, save gas. And if you want to be a pest, ask your MSC for the scientific basis for waiting 100 hours. They won't have an answer.

[deadbug]

My engine will not operate smoothly lean of peak.  Has anybody here ever tried putting GAMIS on our little Lyc. I0360 4-bangers?  I had heard over the years that they were not really effective on those engines.  Just curious...

[Greg_D]

Sure, Gamis will work in your Lycoming IO360.  I used them very successfully in mine.  It just took 3 tweaks to get them set right.  Gami has about a 95% success rate with getting the setup correct the 1st time on the Continental big bore engines.  They say it's usually a 50/50 shot with the Lycomings.

[Cruiser]

Quote: deadbug

My engine will not operate smoothly lean of peak.  Has anybody here ever tried putting GAMIS on our little Lyc. I0360 4-bangers?  I had heard over the years that they were not really effective on those engines.  Just curious...