IO-550 LOP Operations

[Txbyker]

I have had my Ovation for almost a year now with 175 hours and just today I flew LOP for the first time in for a long duration in this plane. My exhaust valves showed a little carbon at annual so thought I would burn EGT a bit hotter.  It has new Tempest FW. I was at 8000 feet and it was 18 degrees C.  Running 2400 RPM and WOT.  Attached is a picture for your critique.  Tell me if things look normal.  I calculated 65% HP and was set to 25 LOP.  

 

Observations -

1.  I lost about 4 kts TAS versus ROP.  For me thats 171 kts LOP.

2.  When switching tanks I got a noticeable surge when the fuel pump was on.  Was I too lean or is that normal?

3.  I could feel the engine rougher than ROP but it seemed to get smoother an hour in.

4  CHTs about 15 degrees cooler than ROP

 

Russ

 

[231LV]

all looks good...don't know what the surge is as I have never had that problem but could be a momentary richening of the fuel flow. LOP equals cooler which equals engine longevity...also lower fuel burn at a slightly slower speed. Exhaust output is "cleaner" than ROP...mechanical advantage of the flame front moving more slowly which allows the power stroke to "push" the piston down rather than suffer the "pounding hammer" when ROP...all in all good...enjoy running LOP...your engine loves it!

[DS1980]

"My exhaust valves showed a little carbon at annual so thought I would burn EGT a bit hotter."

 

By running LOP?

[ArtVandelay]

Do you have GAMI injectors?

Sent from my iPad using Tapatalk

[Txbyker]

"My exhaust valves showed a little carbon at annual so thought I would burn EGT a bit hotter."

 

By running

. I was thinking ROP could contribute to carbon deposits and perhaps hotter EGT could burn cleaner.

[Txbyker]

Do you have GAMI injectors? Sent from my iPad using Tapatalk

No I do not have GAMIs. I might look into them. I have experience with GAMIs I put in my old J.

[ArtVandelay]

No I do not have GAMIs. I might look into them. I have experience with GAMIs I put in my old J.

I'm no expert, but have been told the GAMIs are almost a requirement for the 6-cyl engines, otherwise there is too much spread to run LOP effectively.

[carusoam]

Doing the GAMI spread test answers the question...

What does the procedure say regarding changing tanks? Pump on or not?

There is no pressure gauge, so it is difficult to tell if it is needed.

Without the pump, the FP will momentarily drop some. With the pump the FP will temporarily increase some.

GAMI spread with my engine was minimal. Continental supplied both the injection system and the engine.

The transition is so short would it be noticeable in cruise?

Does the FF change noticeably while making the change?

I would expect following the procedure covers the bases.

In the event of running a tank dry and allowing air to enter the mechanical pump is best countered by having the electric pump running.

The numbers I used to see in my O1 powered O1....

ROP 175kts

LOP 165kts

Rpm was limited to 2500rpm.

LOP at higher altitude is limited to 50dF or so

At lower altitudes it is possible to go 90-100dF LOP. Slower and more efficient....if you like?

Thoughts (and memory) of a private pilot...

Best regards,

-a-

[PMcClure]

When running LOP,  I do get a noticeable surge in the engine along with an increased ff when I turn on the low boost pump. I do always turn it on for the tank change, although it may not be necessary. I did review this issue with my AP who says the boost pump is designed to over power the mechanical pump so FF would increase, which would push the mixture more toward peak EGT and increase the power. 

[Cruiser]

All looks good. 

You do not need GAMIs with the IO550G

CHTs are nice an cool except that pesky #5. I hope you keep it below 400°F on climb out.

 

You will learn to like LOP a lot.

[mooneyman]

What's your fuel flow in that configuration?

[Txbyker]

All looks good. 

You do not need GAMIs with the IO550G

CHTs are nice an cool except that pesky #5. I hope you keep it below 400°F on climb out.

 

You will learn to like LOP a lot.

Thanks Tom. I consulted the pixie fairy about #5 but apparently on the 2005 the alternator has to be removed to get to the bracket that blocks air flow.

Russ

[Txbyker]

What's your fuel flow in that configuration?

I saw 12.4 gph at 8000 but saw 11.8 gph at 11,000 on my second run.

[Txbyker]

I have done several GPH spread test at different altitudes and I am .5 gph spread every time. #5 always last and accounts for .1 gph. Would you try to improve this spread with a GAMI investment?

Russ

[DonMuncy]

Russ,

It is my understanding that the GAMI folks don't try to get closer than .5 gph. But it may be worth it to try. I was very pleased with how much smoother my Continental TSIO360 ran with GAMIs. You might call and ask them what they think. They are nice folks to deal with.

[Cruiser]

I would suggest you try running LOP with your current setup at the altitude you will most fly. Try it and see how it feels. If you can get a smooth ride without engine vibration. I would leave it alone.

If you can't get lean enough then go for the GAMIs. Don is right, GAMI many times can do better but they shoot for .5 gph spread as good enough.

[pinerunner]

ame="DS1980" post="153536" timestamp="1402023181"]"My exhaust valves showed a little carbon at annual so thought I would burn EGT a bit hotter."

 

By running

 

. I was thinking ROP could contribute to carbon deposits and perhaps hotter EGT could burn cleaner.

 

When you're running ROP there's insufficient oxygen to complete the burn so by definition you'll get some kind of soot. Worse some of those incomplete combustion products are likely to be energetic radicals that can initiate polymerization reactions leading to those varnish-like deposits you see when you're tearing down an engine. LOP has the air in excess over the fuel so it should naturally be expected to burn cleaner. It doesn't need to be hotter. 50 LOP and 50 ROP are the same EGT.

[Flymu2]

I ran my engine LOP for about 2 years without GAMI's. There was some roughness but tolerable. The spread was .6-.7 gph. I noticed a change in which cylinder peaked first and a slight increase in the spread. Since I had GAMI's in other planes and I didn't want to spend money cleaning and reinstalling injectors I decided to just go with the GAMIjectors. The engine now runs much more smoothly in all regimes. The spread is about .3 GPH. For the moment I'm happy.

[kmyfm20s]

I ran my engine LOP for about 2 years without GAMI's. There was some roughness but tolerable. The spread was .6-.7 gph. I noticed a change in which cylinder peaked first and a slight increase in the spread. Since I had GAMI's in other planes and I didn't want to spend money cleaning and reinstalling injectors I decided to just go with the GAMIjectors. The engine now runs much more smoothly in all regimes. The spread is about .3 GPH. For the moment I'm happy.

Did you have to do the back and forth with GAMI or did you get the .3 with the first set they sent you?

[Steve Dawson]

When you're running ROP there's insufficient oxygen to complete the burn so by definition you'll get some kind of soot. Worse some of those incomplete combustion products are likely to be energetic radicals that can initiate polymerization reactions leading to those varnish-like deposits you see when you're tearing down an engine. LOP has the air in excess over the fuel so it should naturally be expected to burn cleaner. It doesn't need to be hotter. 50 LOP and 50 ROP are the same EGT.

 

I was just about ready to say that.

[Txbyker]

I put GAMI's in trying to close a .5 gph spread. #3 was first to peak and #5 last, each representing .1 gph. Thoughts were going a bit leaner for #3 and a bit richer for #5 we could get to .2 or .3 on the second go. After replacing those two I am still .5 gph. Now #2 is first and #5 is still last, each about .1 gph from the others. GAMI says I should use a heat gun and see if the probes are connected to the right EGT. They have seen them plugged into the wrong ones in the past with similar results. Any ideas?

Russ

[carusoam]

Russ,

The non-sensible result to your well thought out plan points in the direction of misplaced TCs...

My old engine had a very tight Gami spread on original injectors...

I sense something may be afoul...

Best regards,

-a-

[PhredPhantom]

OK, so I've only owned my 2000 Ovation 2 for a little over a month now.  This past weekend I decided to experiment with the ROP/LOP issue while on a 2 hour trip at 8,000 ft.  I don't have the really cool G1000 panel shown at the beginning of this thread; just the regular old Moritz gauges.  I had the RPM at 2300 and the MAP at 22".  I kept gradually leaning the mixture until I got to 1600 degrees.  Redline is 1650.  I didn't really want to continue leaning because I don't know if I entirely trust the Moritz EGT gauge so I chickened out and enrichened the mixture 50 degrees to 1550 thinking that in case the peak was actually 1600 degrees (but I was a little afraid to chance it any further) I would at least be 50 degrees ROP at best - maybe/likely more ROP than that.

 

My first question is what peak EGT do you normally expect to see with an IO-550 at 8,000 ft?  

 

Second, do you think my EGT readings might have been in error?  I don't have the individual cylinder EGTs like the person who started this thread so I don't know whether the EGT reading I have turns out to be an average or is more reflective of the highest EGT cylinder.  

 

Any comments would be appreciated.

[Greg_D]

Phred, you might want to attend the Advanced Pilot Seminar class in person or online. They teach to do a "big pull" when reducing the mixture to get on the lean side of peak. Gradually reducing fuel just extends the amount of time you are in what they call the "red box", which is where you don't want to be.

At a minimum, please read up on everything and make sure you fully understand it before experimenting with LOP. I have a friend who burned up his turbo Lance's engine by experimenting without fully grasping what was going on. He claimed he didn't have time to attend the course, but he had lots of free time afterwards while waiting for his engine overhaul...

[Txbyker]

OK, so I've only owned my 2000 Ovation 2 for a little over a month now.  This past weekend I decided to experiment with the ROP/LOP issue while on a 2 hour trip at 8,000 ft.  I don't have the really cool G1000 panel shown at the beginning of this thread; just the regular old Moritz gauges.  I had the RPM at 2300 and the MAP at 22".  I kept gradually leaning the mixture until I got to 1600 degrees.  Redline is 1650.  I didn't really want to continue leaning because I don't know if I entirely trust the Moritz EGT gauge so I chickened out and enrichened the mixture 50 degrees to 1550 thinking that in case the peak was actually 1600 degrees (but I was a little afraid to chance it any further) I would at least be 50 degrees ROP at best - maybe/likely more ROP than that.

 

My first question is what peak EGT do you normally expect to see with an IO-550 at 8,000 ft?  

 

Second, do you think my EGT readings might have been in error?  I don't have the individual cylinder EGTs like the person who started this thread so I don't know whether the EGT reading I have turns out to be an average or is more reflective of the highest EGT cylinder.  

 

Any comments would be appreciated.

Seems a bit lean to me.  Here are my last readings at 8000 feet.