LOP IO-360

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JC150

Pre-takeoff checklist
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JC150
I read a thread online that said Lean of Peak should be based off the cylinder that peaks last. Is this correct?

Secondly, I was reading about the "detonation zone", and if you run ROP, you should be no less than 50 ROP, and lean of peak should be greater than 25 degrees LOP. I'm running an IO-360 with GAMI injectors, and if I go beyond 20 degrees LOP I'm getting engine roughness.

I have an E.I. UBG-16 Engine Analyzer. When I go to the lean mode, it tells me which cylinder peaks first, and then if I wanted to lean 30 degrees LOP, it would be based off the cylinder that peaked first, not last. When I go to 30 degrees LOP off the cylinder that peaks first, I'm getting engine roughness.

Finally, would it be dangerous to run it say 10 degrees ROP?
 
20 degrees LOP to 100 degrees ROP is the zone to avoid. Got it.

The articles doesn't mention whether LOP/ROP is calculated from the first or last cylinder to peak. Does anyone know?
 
You want to use the cylinder closest to the peak for your settings typically. This means that if you are leaning for LOP, you use the last to peak. If setting ROP, you use the first cylinder to peak. This assures the other cylinders are further away from the peak than the one you're setting. Ideally, you should have your fuel flows balanced that they peak close together.
I thought it was based off your hottest cylinder... not first or last to reach peak.
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The absolute EGT is by and large meaningless. Slight differences in the position of the sensor in the stack make a lot of difference in the absolute reading.
 
flyingron said:
This means that if you are leaning for LOP, you use the last to peak. If setting ROP, you use the first cylinder to peak.
Click to expand...

Yep. That's how my JPI works. There are two modes for leaning. If in ROP mode, it flags the first cylinder to peak, if in LOP mode, it flags the last to peak. Perhaps the EI has a way to switch leaning modes similar to the JPI?
 
I tried LOP on my 5 hour flight today, from the first cylinder to peak (now I know its the last, EI wont do last cylinder to peak).

With GAMIs, isn't the EGTs supposed to be close together? Could someone tell me if these numbers look okay? 7,000 ft 8.1gph OAT 19C WOT/2400RPM

EGT / CHT
1 - 1248/279
2- 1290/279
3- 1313/303
4- 1236/280

The first cylinder to peak was number 2 and it was 1320 degrees. I leaned until Cylinder #2 was 30 degrees less and it ran really rough.. If I had the JPI and did 30 degrees from the last cylinder to peak, would it run rougher?
 
JC150 said:
The articles doesn't mention whether LOP/ROP is calculated from the first or last cylinder to peak. Does anyone know?
Click to expand...

It depends.

If you're starting from the rich side of the EGT peak, then you choose the last cylinder to peak.

On the other hand, if you're starting from the lean side (as I do), then you choose the first cylinder to peak.

The way I get to my target of 50 degrees LOP is a three step process:
  • first, starting from ROP, I use a "big pull". That means pulling the mixture knob fairly quickly (5 seconds) until I feel the plane decelerate -- I now know that I'm at least 50 degrees LOP.
  • second, I slowly push the mixture knob, using gentle touches and waiting 10 sec between, to make the mixture gradually richer, and I watch only the cylinder that I know from experience will be the first to peak. Once I see it peak, I write down the EGT for that cylinder.
  • Third, I pull the mixture back until EGT on that cylinder is 50 degrees cooler than peak. That's how I get to 50 degrees LOP.
 
ircphoenix said:
I thought it was based off your hottest cylinder... not first or last to reach peak.
Click to expand...

No, as flyingron said, the overall temperature is not meaningful. What's meaningful is the GPM flow rate at which a cylinder experiences its peak EGT.
 
Here's an example chart, for my engine, showing how EGT peaks.

This is sometimes called a "GAMI test". The heavy blue curve is the FF, or fuel flow, in gallons per minute. The other six curves are EGT in Fahrenheit.

In my case, I have six cylinders, and they peak at different fuel flow rates, because fuel to the six cylinders is imperfectly divided by the fuel injection system.

Over the course of 15 minutes, starting from LOP, I gradually pushed the mixture knob forward, in little nudges, making the fuel flow go up from 13 to 16 GPM. As I made the mixture gradually richer in this way, the EGTs at first climbed, and then they peaked. They don't all peak at the same fuel flow.

upload_2016-7-7_17-30-14.png
 
Wow, thank you for the information! Since the UBG-16 only does the first cylinder to peak, I will try the big pull and work my way up and report back.
 
JC150 said:
I tried LOP on my 5 hour flight today, from the first cylinder to peak (now I know its the last, EI wont do last cylinder to peak).

With GAMIs, isn't the EGTs supposed to be close together? Could someone tell me if these numbers look okay? 7,000 ft 8.1gph OAT 19C WOT/2400RPM

EGT / CHT
1 - 1248/279
2- 1290/279
3- 1313/303
4- 1236/280

The first cylinder to peak was number 2 and it was 1320 degrees. I leaned until Cylinder #2 was 30 degrees less and it ran really rough.. If I had the JPI and did 30 degrees from the last cylinder to peak, would it run rougher?
Click to expand...
Disclaimer: I'm not an engine expert or even a mechanic, but I have GAMIs and have been trying to fly LOP for several years.

If you're adjusting the mixture from the rich side, then you set it based on the last cylinder to peak - i.e., the richest cylinder. In your case, something doesn't sound right assuming you have correctly installed GAMIs, unless all the other cylinders peaked while #2 was going from peak to 30 LOP, which doesn't seem likely.

The absolute EGT that each cylinder reads is considered to be less important than the difference in the fuel flow at which the richest and leanest cylinders peak, which should be 0.5 gph or less with GAMIs.

Are you sure your mechanic installed the nozzles correctly? They are custom made for each cylinder based on the results of a GAMI lean test similar to the one someone else posted, done with your original cylinders. Then the test is repeated with the new cylinders and GAMI will tweak the nozzles, ideally until all cylinders peak within 0.5 gph of each other. If the nozzles are interchanged and installed on the wrong cylinders, the results will be poor.

It's not always possible to get all cylinders to peak that close together. My engine, also an IO-360, is unfortunately like that, my #3 and #4 peak first, then #2, then #1 about 0.6 gph leaner than #4. This is after 3 iterations of new nozzles, all aimed at making #3 and #4 richer. I can get #2 and #1 about 20 dF into LOP territory before the engine starts running rough, which is not out of the red box for high power ops. I lose too much speed at lower altitudes by throttling back to less than 65% power, so I only run LOP at altitudes above 6000 MSL, and in fact, at 8000 or above, I run WOT and just lean for peak EGT on #2, and sometimes leave #2 and #1 slightly ROP since no red box exists at the power output levels possible at that altitude.

Three mechanics have tried to determine the reason and none has been able to come up with a clue. One very experienced guy ruled out all pathological reasons for the problem and basically gave up.

One engine expert who sometimes posts on PoA suggested to me that I might be being too conservative in my ops because it's hard to make an IO-360 detonate, and that I can still run WOTLOP at altitudes below 8000. I'm chicken.

I hope you can figure out what is going on with your engine. Good luck!
 
Is this a Continental or Lycoming? Continental says you can do anything you want with the mixture knob from full rich to so lean that the engine is misfiring provided that you are at or below max recommended cruise. You're not going to get it to detonate at any setting at those power levels. The Red Box is a Lycoming invention. The fact that the nozzles can't be tweaked probably means the fuel distribution ahead of that is restricted to those cylinders.
 
I believe Continental says under 65% power you can do whatever you want, and for Lycoming it's 75%. I cruise at 65%. I don't have GAMI's or a very functional EGT but my limitation for running LOP is a power one. I can throttle it with the mixture without roughness. If you're pushing the upper edge of the power band, instrumentation is important. Otherwise, it doesn't matter much because you won't blow your engine up either way.
 
flyingron said:
Is this a Continental or Lycoming? Continental says you can do anything you want with the mixture knob from full rich to so lean that the engine is misfiring provided that you are at or below max recommended cruise. You're not going to get it to detonate at any setting at those power levels. The Red Box is a Lycoming invention. The fact that the nozzles can't be tweaked probably means the fuel distribution ahead of that is restricted to those cylinders.
Click to expand...
Good question. Not sure about the OP; mine is a Lycoming. IO-360 A1B6.
 
I run full rich until above pattern altitude then start leaning until 150 ROP, that gives me plenty of margin, then I run about 50 LOP, any more it starts to feel like it's missing, I have GAMIs. I thought the injectors were marked for each cylinder...
 
I tried it out again today. This might be a long read, but please continue reading because I'm trying to learn!

Previously I leaned from the rich side until the first cylinder peaked, then decreased the mixture until the EGT was 30 degrees less than peak. I now know it should be the last cylinder to peak for LOP ops. A previous recommendation above was to start from the lean side and richen until it peaks, then lean again until I get the desired LOP value.

Today, I did just that. I got 8.7 gph doing 30 LOP. But how come when I tried 30 LOP from the first cylinder to peak I was doing 8.1 gph? Shouldn't the last cylinder to peak be a lower GPH value than the first cylinder to peak?

Previously: 7,000 ft, 8.1gph, OAT 19C WOT (23")/2400RPM - 30LOP from first cylinder to peak (from the rich side)

Today: 7,000 feet, 8.7 gph, OAT 18C, WOT (23")/2400RPM - 30LOP from the first cylinder to peak (from the lean side = last cylinder to peak from the rich side)

EGT/CHT
1- 1252/266
2- 1291/268
3- 1301/294
4- 1221/284

I did the GAMI test manually and GAMI sent me a new injector for one of the cylinders to make all the cylinders peak closer together. However, I notice the plane is running more rough LOP than it did before. Is it okay to continually run the plane with engine roughness and the airframe vibrating more than usual? Only happens when LOP.
 
Question for you guys:
Our IO-360 C1C just has the little egt gauge with the pilot move able needle.
How do you recommend I lean it most effectively?
The standard 'lean till rough, then enriched slightly'? Or some other fashion?
Sorry for the slight thread hijack!
 
FarmerBrake, I think you're doing it right. That's how I would do it anyway. Maybe someone else has a suggestion.
 
I pulled the GAMI injectors out of my IO-360 mooney as we couldn't make them run right, even at gami headquarters they couldn't make them run right.

The injector is concave at the bottom and whenever going though peak, only at WOT, the air bleed hole at the side of the injector behind the screen would spit fuel out. The factory injectors are flat on the bottom and wouldn't do that. The band aid fix to this is to back off 1/2" of M.P. then lean. I think that's a joke so we pulled them out.

I'll try to find the video on YouTube as a beech guy video the leaky Gamis with a small camera mounted under the cowl.

Needless to say when the fuel spit out the side it would not run lean of peak well.

Another thing is if you have a powerflow exhaust your not going to be able to run deep Lop like you could with a factory exhaust. I can only run about 30 lop but really cruise at 10lop, adding the power flow really made the engine come alive but also changed the lop curve. The good thing is the Chts came down about 30f at any equivalent power setting so running closer to peak egt is probably a wash when compared to higher Chts and more lop with factory set up.


Sent from my iPhone using Tapatalk
 
Aaron, did you find the video by chance?
 
I've operated the 200HP Lycoming IO360A3B6D with PowerFlow exhaust in my Mooney LOP for over 10 years at over 100 hours per year. At lower altitudes, say 3000', I can lean to 30 or 40 deg LOP easily with the engine running very smoothly. (I usually don't because the plane is slowing down too much for me at such a setting.) At higher altitudes, say 7,000' and above, I only lean to about 5 or 10 deg LOP (based on last cylinder to peak, #2 in my case). More than that and I can start to get some roughness. My CHTs are all in the 320 to 350 dF range. For a 200HP engine 65% power LOP is 8.7 GPH. If even a little LOP I will be at that fuel flow at around 7000'. At 7,000' and 5 to 10 deg LOP on the last cylinder to peak my Garmin 430 E6B always calculates between 148 to 153 kts TAS.
 
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Maybe I'm missing something, but why would EGTs range from the 320-350F range as Lance mentions in the above post, all the way upwards of 1500F as shown in NoHeat's graphical output? What's up with that? Different engines and sensors and all sure, but do EGTs really vary that much across the envelope?
 
Those are the right range for CHT. It's not even close for EGT whether you are using Farenheight or Celsius.
 
Here is my 360, I do have GAMIs, I lean 70 LOP, it was just missing a little, so I enriched enough to smooth it out, notice 2nd peak but they settle back down:
90904474f1eab1a915c95413ea72ee20.png
 
Auburn2002 said:
Maybe I'm missing something, but why would EGTs range from the 320-350F range as Lance mentions in the above post, all the way upwards of 1500F as shown in NoHeat's graphical output? What's up with that? Different engines and sensors and all sure, but do EGTs really vary that much across the envelope?
Click to expand...
That was definitely a typo. Sorry.
As an aside absolute EGTs are pretty meaningless. Depends on where the mechanic put the probes.
 
teejayevans said:
Here is my 360, I do have GAMIs, I lean 70 LOP, it was just missing a little, so I enriched enough to smooth it out, notice 2nd peak but they settle back down:
90904474f1eab1a915c95413ea72ee20.png
Click to expand...
What altitude were you flying at when this data was collected?
 
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