New Ovation owner, seeking adivice on what most of you run LOP or ROP and why

[bg8810]

Its been talked about to death, and I have seen many arguments on either side. I currently have 3 people with Mooney experience saying only ROP, the POH says ROP, and I have another couple guys with Mooney experience saying LOP. I have noticed it runs a little rougher when LOP also cylinders are a little cooler which is nice. I would just like to know what do the Ovation drivers on here use and why? I do have a EDM 700 on the plane to help in leaning btw. Thanks for any and all your input! By the way, I am absolutely loving the Mooney!  

Edited October 29, 2019 by bg8810
misspelled a word

[MooneyMitch]

Probably many replies you’ll receive will be quite technical in nature. Mine is not.

My experience with my former IO550G was this.....I purchased the  Ovation with approximately 1700 hours on new factory engine.  The previous owner flew that engine approximately 200 hours per year, long distances at 50 LOP, continuously.

During pre buy, borescope revealed no issues other than very smooth cylinder walls, no cross hatch marks whatsoever.  Compressions in the lows 70’s.  Oil usage was 15 hours per quart.  I purchased.

I added additional 500 + LOP hours on that engine prior to OH at PowerMasters, Tulsa.

PM mechanic that disassembled my engine asked, this engine is a LOP engine, right?

How did you know that, I asked? His reply, I instantly recognize a LOP engine as it’s very clean inside.

That’s it.  

Oh yes, at altitude, approximately 12.8 (or less) at 175 kts.

Edited October 29, 2019 by MooneyMitch
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[gsxrpilot]

LOP = more hours out of the engine and more flight time from each gallon. What's not to like.

[MooneyMitch]

The Ovation, my opinion.... a fabulous airplane!! 

[MooneyMitch]

Another thought.... running a bit rough at 50 LOP?  Richen up just a bit and see.  You’ll find the sweet spot ( lots of variables involved). 

 

[Parker_Woodruff]

Yeah, how far LOP are you for the rough engine.  You may need to do a GAMI test or you may just be too far LOP.

[gsxrpilot]

A rough running engine while LOP is because of uneven fuel distribution between cylinders. As you go leaner and leaner, eventually you get to idle cut off. If your fuel distribution is not balanced, one cylinder might be at idle cutoff while another cylinder is just at peak. That equals a rough running engine.  A GAMI Lean test will show the level of balance or imbalance in the fuel distribution. If fuel distribution balance is perfect, the engine will run perfectly smooth all the way to idle cut off.

Typically a distribution or "GAMI spread" of 0.5 gph or less, between the first cylinder to reach peak and the last cylinder to reach peak, is good enough. A spread greater than 0.5 gph will cause most engines to run rough at anything beyond 20° or 25° LOP.

[FlyingScot]

3 hours ago, gsxrpilot said:

LOP = more hours out of the engine and more flight time from each gallon. What's not to like.

 

3 hours ago, MooneyMitch said:

The Ovation, my opinion.... a fabulous airplane!! 

Absolutely to both. I have run ROP (on rare occasion) and 30-50 LOP (almost always), GAMI. Engine is smooth, even at 50 LOP = @10K' ~12GPH @175kts. Temps great, engine purrs, boroscope images are cylinders-of-the month. Range/endurance much improved LOP = better reserves IFR at same load.

Leaner eventually leads to idle cut off, which for me is pretty uniform/abrupt (no significant leading roughness, which I take to mean pretty good balance across injectors).

How can you beat it. I have been current in a whole lot of different types of aircraft, liked them all (mostly ;-), but I honestly can say I truly love the Ovation...

[kortopates]

3 hours ago, gsxrpilot said:

A rough running engine while LOP is because of uneven fuel distribution between cylinders. As you go leaner and leaner, eventually you get to idle cut off. If your fuel distribution is not balanced, one cylinder might be at idle cutoff while another cylinder is just at peak. That equals a rough running engine.  A GAMI Lean test will show the level of balance or imbalance in the fuel distribution. If fuel distribution balance is perfect, the engine will run perfectly smooth all the way to idle cut off.

Typically a distribution or "GAMI spread" of 0.5 gph or less, between the first cylinder to reach peak and the last cylinder to reach peak, is good enough. A spread greater than 0.5 gph will cause most engines to run rough at anything beyond 20° or 25° LOP.

Remember it takes 2 things to run smooth LOP, mixture distribution is key but so is a healthy ignition system. The ignition system is under a lot more stress LOP than ROP and if there are any issues with it, they'll show up right away under the stress of firing LOP. Hence why we do the LOP Mag test in flight to check it out. So roughness encountered from LOP ops can come from cylinder power imbalance (such as poor mixture) or it can come from faulty ignition leading to premature misfire. Only a review of your downloaded diagnostic engine data can tell you the difference! (although sometimes the cause can be so obvious its clearly visible in flight)

[Niko182]

At the beginning of ownership, I flew the plane strictly ROP. Once the Gami injectors and JPI 900 went in I started running it LOP and at peak. low down i'll fly it LOP since theres no need to get there fast, above 8000, I like peak alot.  I'm however starting to fly it more and more LOP.

[MIm20c]

53 minutes ago, kortopates said:

Remember it takes 2 things to run smooth LOP, mixture distribution is key but so is a healthy ignition system. The ignition system is under a lot more stress LOP than ROP and if there are any issues with it, they'll show up right away under the stress of firing LOP. Hence why we do the LOP Mag test in flight to check it out. So roughness encountered from LOP ops can come from cylinder power imbalance (such as poor mixture) or it can come from faulty ignition leading to premature misfire. Only a review of your downloaded diagnostic engine data can tell you the difference! (although sometimes the cause can be so obvious its clearly visible in flight)

I agree with the above. You also might want to look back at the logs. If one (or both) of the mags has not been opened up in the past 1-2k hours you might want to send it (them) in for an iran. 

[KSMooniac]

Tempest fine wire plugs help tremendously too, after you get the fuel/air balance optimized. Especially on the IO-550 you should be able to lean to cutoff and stay smooth all the way!

Sent from my LG-US996 using Tapatalk

[Niko182]

8 minutes ago, MIm20c said:

I agree with the above. You also might want to look back at the logs. If one (or both) of the mags has not been opened up in the past 1-2k hours you might want to send it (them) in for an iran. 

Pretty sure its required every 500 hours.

[jaylw314]

Just now, Niko182 said:

Pretty sure its required every 500 hours.

Not if the aircraft is flown under part 91, but yes, a very good idea nonetheless...

[MIm20c]

Just now, Niko182 said:

Pretty sure its required every 500 hours.

I agree but it’s not a requirement. The mags on the Ovation are pretty durable so even 1k is doable. 

[MarkD34M]

Are you guys running 75% power and then going LOP or starting at something somewhat less like 65% or 70%. I flew my (new to me Ovation) LOP the other day and it was smooth - 12.3 GPH and 168 knots but leaned from a 65% ROP configuration to LOP. Thoughts / feedback?

[GeeBee]

That is about what I run at 65%.

 

 

[gsxrpilot]

9 minutes ago, MarkD34M said:

Are you guys running 75% power and then going LOP or starting at something somewhat less like 65% or 70%. I flew my (new to me Ovation) LOP the other day and it was smooth - 12.3 GPH and 168 knots but leaned from a 65% ROP configuration to LOP. Thoughts / feedback?

I generally always, and in the beginning always would reduce to 65% and then pull back to LOP. At 65% power I'm pretty sure I can't hurt the engine even running right at peak. After many hours of LOP and knowing exactly what to expect and what fuel flow to aim for, I sometimes run LOP at 70% or even 75%. But in the beginning, 65% is safe for the engine. 

[kmyfm20s]

The POH does have LOP settings for the ovation. 

[Niko182]

8 minutes ago, gsxrpilot said:

I generally always, and in the beginning always would reduce to 65% and then pull back to LOP. At 65% power I'm pretty sure I can't hurt the engine even running right at peak. After many hours of LOP and knowing exactly what to expect and what fuel flow to aim for, I sometimes run LOP at 70% or even 75%. But in the beginning, 65% is safe for the engine. 

Start at 75 percent power and then lean down

[TGreen]

I run 50 degrees LOP, see 165-168 true airspeed, hottest cylinder between 320 and 330 degrees. 

Only exception is around mountains if I am concerned about downdrafts. Then ROP. 

[TGreen]

And with a little tailwind it's amazing how well that works out!

https://flightaware.com/live/flight/map/N451US/history/20191029/1930Z/KHWD/KSNA

[StevenL757]

On 10/29/2019 at 12:05 PM, bg8810 said:

Its been talked about to death, and I have seen many arguments on either side. I currently have 3 people with Mooney experience saying only ROP, the POH says ROP, and I have another couple guys with Mooney experience saying LOP. I have noticed it runs a little rougher when LOP also cylinders are a little cooler which is nice. I would just like to know what do the Ovation drivers on here use and why? I do have a EDM 700 on the plane to help in leaning btw. Thanks for any and all your input! By the way, I am absolutely loving the Mooney!  

40-50 degrees LOP will keep your cylinders happy.  If you don’t have finewire plugs in your IO550, consider spending some money on them, as well as a gold seal ignition harness...which you may already have.  Combined with Bendix mags, you’ll have arguably the best ignition system for that engine platform.  LOP has known to play havoc on your exhaust system and muffler over time, but it’s a small price to pay versus running ROP, where you’ll likely wind up doing premature cylinder work.

Congratulations on Ovation ownership.  You won’t regret the decision.

Steve

[MooneyMitch]

My LOP operations were not limited to specific altitudes or specific power settings.

Many flights were local at altitudes below 4,000 ft, and at reduced power settings.

Sometimes, at 20" and LOP, which would produce 8 GPH and 150 kts or better.  Cylinder temps were in the 280-300.  There were no fine wire plugs installed in this engine.

All seemed to be just fine. 

Until I learn otherwise, the OH'd Powermasters IO550G is traveling around the Eastern seaboard just fine, to this very day. 

Others may have different experiences.

A fine engine and a darn fine airplane! 

Edited October 30, 2019 by MooneyMitch
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[RogueOne]

What RPM are you running with LOP operation?  Missile  Shows 65% @ MSL with 22”MP 2350RPM and 15.7gph

55%@7500 19MP 2250RPM 13.9gph

65%@12500 20MP 2550RPM 15.7

55%@12500 18MP 2250RPM 13.9GPH

POH does not reference % LOP or %ROP..

Thanks for your numbers

IO550 Missile