LOP - AMAZING - try it if you can and haven't yet

[Seth]

Alright - I'm a LOP fan now.

 

This thread is not meant to stir arguments, though I'm sure it will, but after operating ROP for my first 900 hours, after just 5 hours using LOP, I'm a fan (and yes, I'm right about 905 hours).

 

As noted in a separate thread, during a recent partial under warranty top overhaul, my injectors were put back in the wrong order causing a hot and lean #2 cylinder.  That was recently corrected and on a flight down to South Carolina for a wedding this weekend, I finally got the fuel flow that the Mooney Missile can perform with it's speed.

 

Due to the lean #2 cylinder, I have had to run rather Rich.  Now, I'm have all my cylinders peaking at once which means I can run a full 1 GPH leaner ROP, but my engine now really runs LOP smoothly.

 

So, I dropped from doing 185 knots at 18GPH to 175 knots at 11.6-12.0 GPH.  That is significant. 

 

6 GPH for about 10 knots.  If I ran at 182 knots at 16.7 GPH ROP then it's still a 4-5 GPH savings for 7 knots.   

 

It increases the range of my aircraft I'm running well LOP (30-70 degrees LOP).  For instance, for my trip this weekend, I matched the MPG of my former F model if not besting it.  At one point over NC and VA, I hit 188 knots on 11.8 GPH.  That was only with a tailwind of about 10-15 knots. 

 

As long as no cylinder has an EGT too close to peak so I don't burn up the valves, I'll continue to be a big fan of LOP. 

 

Lower fuel burn, small speed drop off, cooler CHTs, it's a winner.

 

If you have an engine monitor and have the ability to try LOP.  Try it.  I wish I had earlier.  That lowers my cost by 5-6 GPH or $30-$40 per hour.  For 100 hours per year, that's right now $3000 to $4000 per year which is significant to the overall flying budget (1/3 less in fuel costs which are about half the budget or 1/6 less per year in costs).

 

I'm only comfortable running LOP right now at higher altitude cruise, but as I practice and get more comfortable, I'll learn to LOP at lower altitudes as well as during decent. 

 

-Seth

[jetdriven]

Welcome to the church of LOP. Science and hard data winning out over closely-held superstition one pilot at a time

[1964-M20E]

Congratulations and welcome.

[Seth]

Hey, I know they used to use it in WWII, and that it does work, but I've never had a smooth running LOP experience before.  With the GAMI injectors in the right place, my spread is so small and it just runs smooth.

 

I'm curious to those that have converted (and I'm reading and researching a lot), how rich can my leanest cylinder be EGT wise?  20 degrees?  30?  50?

 

Also, how do you usually handle LOP decents? 

 

I know about the "red box" but what are your normal experiences and power settings?  Specifically IO-550 users, but also all other engines that are run LOP on the board.

 

Thanks, just trying to get real data from actual LOPers in real life, not just the "book."

 

-Seth

[NotarPilot]

Don't you mean how LEAN can your leanest cylinder be EGT wise? I think 20-50F on the rich side at high power settings is right in the red box.

[WardHolbrook]

Hey, I know they used to use it in WWII, and that it does work, but I've never had a smooth running LOP experience before.  With the GAMI injectors in the right place, my spread is so small and it just runs smooth.

 

I'm curious to those that have converted (and I'm reading and researching a lot), how rich can my leanest cylinder be EGT wise?  20 degrees?  30?  50?

 

Also, how do you usually handle LOP decents? 

 

I know about the "red box" but what are your normal experiences and power settings?  Specifically IO-550 users, but also all other engines that are run LOP on the board.

 

Thanks, just trying to get real data from actual LOPers in real life, not just the "book."

 

-Seth

Instead of asking a bunch of questions on this forum, why don't you take a portion of that $3000 to $4000 annual savings and invest in some serious training by the guys who reinvented the way piston airplanes are being flown? http://www.advancedpilot.com/

 

You can take the course on site or online either way it's probably a good investment.

[NotarPilot]

I think that's easier said than done, besides I would have to hear some very compelling reviews to get me to part with $995 or even $395 for the online course, and I haven't yet.

[WardHolbrook]

You haven't spoken to the same guys I have then. That's why I made the suggestion. (Grin) 

 

Yes it's expensive, but so is a top overhaul if you happen to muff something up. I've never found additional training not to be worthwhile. 

[Seth]

I agree - don't want to cause an expensive issue that I could have avoided by burning up my engine. 

 

I'm still reading a lot and talking a lot, but I was just curious how people tend to in real world experience deal with the final cylinder to peak.  How far can you usually get that cylinder on the lean side before your first cylinder starts to run rough due to needing fuel?  20 degrees LOP? 50 LOP?  Just curious.  All of mine peaked at almost the same time so I was able to get the last one pretty well LOP, but I was wondering what others have experienced.

 

-Seth

 

 

For instance:

 

 

Red Box = No Fly Zone

At and below about 60% power, there is no red box. Put the mixture wherever you want it.
At about 65% power or so, 100ºF ROP to Peak.
At about 70%, 125ºF ROP to 25ºF LOP.
At about 75%, 180ºF ROP to 40ºF LOP.
At about 80%, 200ºF ROP to 60ºF LOP.

 

 

But what are you actually seeing?

[DS1980]

Just curious. What were your concerns about it before?

[Awful_Charlie]

I've always been a fan of LOP as long as the engine will take it.  Last time out, FL 95, 10degC:

KIAS KTAS GPH   nm/USG

164 194     21.8    8.9

160 189     16.2   11.7

148 175     14.6   12.0

I didn't want to stay on the 16.2GPH for too long (which was peak EGT), as CHT's were starting to get towards my limit, so somewhere around 15.5 may have been a better TAS/mpg tradeoff, but that's still a 5GPH+/20%+ saving on ROP.

Of course, it also depends on you attitude towards money and time!

[aaronk25]

Every engine is different and play with it a bit. Get it 50 lean of peak and then over a period of a couple mins bring fuel flow back closer to peak in small increments and watch CHT and you will notice that after a certain amount of fuel added any more doesnt result in much more power but will drive CHT up exponentially so figure out the power setting and save it. Remember limit Cht to 380 or less.

For example my J will run 148kts with chts around 300-330. 152 at Cht of 340 and 157 at 360 Cht.

I won't go into altitude and fuel flow but you get the picture. If turbo inlet temp is a factor don't run in excess of the limitations.

[aviatoreb]

I've always been a fan of LOP as long as the engine will take it.  Last time out, FL 95, 10degC:

KIAS KTAS GPH   nm/USG

164 194     21.8    8.9

160 189     16.2   11.7

148 175     14.6   12.0

I didn't want to stay on the 16.2GPH for too long (which was peak EGT), as CHT's were starting to get towards my limit, so somewhere around 15.5 may have been a better TAS/mpg tradeoff, but that's still a 5GPH+/20%+ saving on ROP.

Of course, it also depends on you attitude towards money and time!

 

Hi Awful.

 

What can your M do at 21.8gph at 12k?  Seem like >200TAS...your plane seems faster than book.

 

Folks, I sat in awful's M with him driving, and I can attest that I was very impressed with the seemingly faster than book speeds.

[jetdriven]

Every engine is different and play with it a bit. Get it 50 lean of peak and then over a period of a couple mins bring fuel flow back closer to peak in small increments and watch CHT and you will notice that after a certain amount of fuel added any more doesnt result in much more power but will drive CHT up exponentially so figure out the power setting and save it. Remember limit Cht to 380 or less.

For example my J will run 148kts with chts around 300-330. 152 at Cht of 340 and 157 at 360 Cht.

I won't go into altitude and fuel flow but you get the picture. If turbo inlet temp is a factor don't run in excess of the limitations.

 

I have found anything leaner than 15-25 LOP results in a huge speed loss for a correspondingly miniscule fuel flow reduction.

[Seth]

Just curious. What were your concerns about it before?

I didn't have an engine monitor in my F model and in the Missile I wanted to break it in ROP (even though I know you can break in an engine LOP).  WhenI was ready to give it a try, I had the cylinder problem which led to the top and another break in period.  Then I had the hot cylinder which was caused by the local mechanic performing the Top OH putting the fuel injectors back on in the wrong locations.  It would not run LOP smoothly because I had one very lean cylinder.  The fuel injectors are in the right place now, the hot cylinder is in line, and everything peaks at the same time, so I decided to finally give LOP a shot and, to say the least, I'm impressed now that my engine runs smoothly LOP.

 

-Seth

[Seth]

Every engine is different and play with it a bit. Get it 50 lean of peak and then over a period of a couple mins bring fuel flow back closer to peak in small increments and watch CHT and you will notice that after a certain amount of fuel added any more doesnt result in much more power but will drive CHT up exponentially so figure out the power setting and save it. Remember limit Cht to 380 or less.

For example my J will run 148kts with chts around 300-330. 152 at Cht of 340 and 157 at 360 Cht.

I won't go into altitude and fuel flow but you get the picture. If turbo inlet temp is a factor don't run in excess of the limitations.

 

Gotcha - I was indeed noticing how sensitve the mixutre vs temps were on the Lean side of the peak as I worked to see how lean I could get it before roughness.  My CHTs were cool - only in the ROP climb with gobs of power did I see anything in the 370s and 380s.  The hot cylinder used to spike into th 400s during climb, but that's not an issue anymore.

 

-Seth

[fantom]

Alright - I'm a LOP fan now.

 

This thread is not meant to stir arguments, though I'm sure it will, but after operating ROP for my first 900 hours, after just 5 hours using LOP, I'm a fan (and yes, I'm right about 905 hours).

 

 

 

 

Can't stir any arguments, Seth, since you were the LAST holdout!

[Earl]

I need to get GAMI injectors installed on my next annual.  I have tried LOP and it runs too rough.  Did a GAMI check and sent the results off the advancedpilot and they said it wasn't awful but not good enough for LOP.

 

As for the red box, my recollection from the AP course was below 65% power you are outside the red box.  I run at 65% power, burn 11gph at ~165 kts (at 10,000 feet) and my hottest cylinder (#6) is usually at around 365 degF with a quarter to third of cowl flap extension.  In the summer heat I sometimes need a bit more cowl flaps to stay below 370 degF which is my target for the hottest cylinder.

[Awful_Charlie]

Hi Awful.

 

What can your M do at 21.8gph at 12k?  Seem like >200TAS...your plane seems faster than book.

 

Folks, I sat in awful's M with him driving, and I can attest that I was very impressed with the seemingly faster than book speeds.

 

Cheers Erik

I'll have to come back to you for that - 12k wouldn't be a 'normal' cruising alt for me (I'd go higher if the wind wasn't against me, and lower if it was), and neither would 21.8GPH! I hope to be 'out and about' over the next week or two, so will have to see and report back.

http://mooneyspace.com/gallery/image/33952-/

is within 2% of book for 32"/2400 and 15.8GPH (which I just dug out from the JPI data!)

Ben

[KSMooniac]

I think that's easier said than done, besides I would have to hear some very compelling reviews to get me to part with $995 or even $395 for the online course, and I haven't yet.

 

It is BY FAR the best money I've spent as an owner.  Period.  Every owner should take the course.  It is that good.  I learned more there in 2.5 days than in many full semester engineering courses.  I've been saying this for the 6+ years since I took it and doubt you would be disappointed.  They'll even refund your money if you don't think it was worth it.

[aviatoreb]

 

Cheers Erik

I'll have to come back to you for that - 12k wouldn't be a 'normal' cruising alt for me (I'd go higher if the wind wasn't against me, and lower if it was), and neither would 21.8GPH! I hope to be 'out and about' over the next week or two, so will have to see and report back.

is within 2% of book for 32"/2400 and 15.8GPH (which I just dug out from the JPI data!)

Ben

 

 

I always figured that 200K at 12K was a really special thing.  I think your Bravo is every bit as fast as a rocket!  So just for bragging rights - that's the 200 at not required O2 level.

 

Make a low pass over Dresden next week - I will be in some academic building there working in 1.5 weeks.  I will listen for the TSIO540 sounds.

[aaronk25]

I have found anything leaner than 15-25 LOP results in a huge speed loss for a correspondingly miniscule fuel flow reduction.

I should have clarified a bit, but only ment to say that the red box isn't definitive but definitely do notice as you get closer to the red box how in order to get a few knots more the temps get hot quick.  I also agree with you Byron that there isn't any measurable gains in efficiency by running more than 20degrees lop and I'd bet that any gains are a result of lower airspeed.

 

if your running more than 20 LOP how about slow up the prop and then run 20 LOP.  20LOP at a lower rpm takes less fuel than 50LOP at a higher.  In fact I've noticed that Peak at a lower rpm and LOP at higher, given the fuel is the same is pretty comparable.  

[Seth]

I need to get GAMI injectors installed on my next annual.  I have tried LOP and it runs too rough.  Did a GAMI check and sent the results off the advancedpilot and they said it wasn't awful but not good enough for LOP.

 

As for the red box, my recollection from the AP course was below 65% power you are outside the red box.  I run at 65% power, burn 11gph at ~165 kts (at 10,000 feet) and my hottest cylinder (#6) is usually at around 365 degF with a quarter to third of cowl flap extension.  In the summer heat I sometimes need a bit more cowl flaps to stay below 370 degF which is my target for the hottest cylinder.

Do it.  I had them on the Missile but after the TOP OH they were installed in the wrong place.  After I finally had them rechecked and reinstalled properly it makes a HUGE difference. 

 

LOP cruise is going to make a huge difference.  And when I want to go that extra 7-10 knots ROP, I always can.

 

-Seth

[Seth]

I should have clarified a bit, but only ment to say that the red box isn't definitive but definitely do notice as you get closer to the red box how in order to get a few knots more the temps get hot quick.  I also agree with you Byron that there isn't any measurable gains in efficiency by running more than 20degrees lop and I'd bet that any gains are a result of lower airspeed.

 

if your running more than 20 LOP how about slow up the prop and then run 20 LOP.  20LOP at a lower rpm takes less fuel than 50LOP at a higher.  In fact I've noticed that Peak at a lower rpm and LOP at higher, given the fuel is the same is pretty comparable.  

 

Neat - i'll have to relearn my engine.

 

-Seth

[Parker_Woodruff]

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