JonJay

JonJay

Well Known Member
Although I spend most of my time LOP, I am a little confused about ROP operations. I have an EDM930. I have found very good procedures to find LOP, however, I dont get how to find peak when running hard without going into the dreaded detonation zone.
For now, I have been roughing the numbers by fuel flow and leaning to Best Power, checking against my EGT's and aproximating 100ROP. I know the JPI product will do this for me and be more accurate, but the procedure requires finding the peak, dead in the red box.
Suggestions?
 
You're supposed to be full rich when over 75%

If by "running hard" you mean you're over 75% power (23/2400), then I'm not sure why you care where peak is. Any time you're over 75%, you should be full rich.

I feel like a heretic for saying it these days, but the manufacturer recommends that you run it on the rich side of peak. Why don't you figure out LOP operations AFTER you get the manufacture's recommended method down pat.

Unless you just want to use the old fashioned method of leaning to roughness, you can't run LOP or ROP unless you know where peak is. Pull it back to 55% (22/2100) and learn how to find peak on your JPI. It's not going to self destruct if you run it in the "Red zone" when you're under 75%.

But whatever you do, leave it full rich when you're over 75%. I think even the LOP faithfull will tell you the same.
 
jonbakerok said:
If by "running hard" you mean you're over 75% power (23/2400), then I'm not sure why you care where peak is. Any time you're over 75%, you should be full rich.
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Ah...so that's where all the 100LL is going!!!

The only time my mixture is ever full rich with the engine running is for the first 10 or so seconds of a takeoff run. YMMV.
 
ut whatever you do, leave it full rich when you're over 75%. I think even the LOP faithfull will tell you the same.
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Actually, probably not ;-)

For more info, you can Google "WOTLOPSOP" or "The Big Mixture Pull" but basically you can run high power settings lean of peak, as long as you are very lean.

It's also perfectly OK to run ROP at high power settings, and you can make more power ROP. Just make sure you're way rich (like 200 degrees).

First, make sure your engine is set up properly, so that you are more than 200 degrees ROP at sea level WOT. On a 200HP motor, this will be around 18.5-19 GPH or more total. All of the absolute EGT numbers should be at least 200 degrees less than your normal peak (which is usually around the same spot).

If your engine monitor has the capability to "normalize" the EGTs, do this on your initial climb. The EGTs will drift down as you continue to climb, but you can gradually pull the red knob back to keep them where they were on takeoff. This will keep you out of the red box.
 
Yes, running hard, over 75% power. I am not trying to start another thread about LOP/ROP operations, so, please help me with my question if you can or call me an idiot if you prefer but do it somewhere else and I respect your opinion. I am going to lean. The manual states never to lean beyond 150deg ROP above 75% power, but it does not say never lean.

So, I use the red knob on both sides of that "magic non existent 75% cliff". I only use full rich power on take off unless I am at a high elevation field ( have not been to one yet), and I ground lean, aggressively, when I am taxiing. So not sure why you would run full rich any time other than take off and not even then if you are at altitude.
So, still looking for procedures, others that also use the red knob above 75% power. I dont think it makes sense to sacrifice that many dinosaurs when I want to run hard, which frankly is not that often, but I still want to do it! I want to run hard and clean.

My lycoming manual standard power chart publishes the curves for best power and best economy. The best power curve goes well beyond 75% and shows that curve through different RPM's and fuel flows. You can not match the fuel flow shown for best power at a given RPM without leaning. If you are not leaning, are you even generating the best power?
I have not taken altitude into consideration yet as I am still struggling to learn all of this but the chart does not reference a base altitude so perhaps it does not affect the curve?
When I am running matched up to the Power Curves with Fuel Flows per the manual, I feel I am operating within recommended ranges. A quick check of EGT's and things seem to match up intuitively in the 150ROP area so I believe I am leaning in the right area above 75% power. I would just like to use the JPI Lean Find mode properly when above 75%, or so, and can't do it without letting the computer find the peak which means I just ran too lean. Perhaps JPI is behind the curve? Ha, thats a joke. I love my EDM.
 
flyeyes said:
Actually, probably not ;-)

For more info, you can Google "WOTLOPSOP" or "The Big Mixture Pull" but basically you can run high power settings lean of peak, as long as you are very lean.

It's also perfectly OK to run ROP at high power settings, and you can make more power ROP. Just make sure you're way rich (like 200 degrees).

First, make sure your engine is set up properly, so that you are more than 200 degrees ROP at sea level WOT. On a 200HP motor, this will be around 18.5-19 GPH or more total. All of the absolute EGT numbers should be at least 200 degrees less than your normal peak (which is usually around the same spot).

If your engine monitor has the capability to "normalize" the EGTs, do this on your initial climb. The EGTs will drift down as you continue to climb, but you can gradually pull the red knob back to keep them where they were on takeoff. This will keep you out of the red box.
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Excellent. I read those articles a bit ago.
I am set up well, 17 GPH (180HP) out of my 200ft elev. field. My EGT's are defineatly more than 200 deg. of normal peaks. So, I will try the normalizing technique as that makes perfect sense to me. No sense in wasting the fuel and I personally believe that my engine will thank me later for running cleaner.
Thanks.
 
JonJay said:
Yes, running hard, over 75% power. I am not trying to start another thread about LOP/ROP operations, so, please help me with my question if you can or call me an idiot if you prefer but do it somewhere else and I respect your opinion. I am going to lean. The manual states never to lean beyond 150deg ROP above 75% power, but it does not say never lean.

So, I use the red knob on both sides of that "magic non existent 75% cliff". I only use full rich power on take off unless I am at a high elevation field ( have not been to one yet), and I ground lean, aggressively, when I am taxiing. So not sure why you would run full rich any time other than take off and not even then if you are at altitude.
So, still looking for procedures, others that also use the red knob above 75% power. I dont think it makes sense to sacrifice that many dinosaurs when I want to run hard, which frankly is not that often, but I still want to do it! I want to run hard and clean.

My lycoming manual standard power chart publishes the curves for best power and best economy. The best power curve goes well beyond 75% and shows that curve through different RPM's and fuel flows. You can not match the fuel flow shown for best power at a given RPM without leaning. If you are not leaning, are you even generating the best power?
I have not taken altitude into consideration yet as I am still struggling to learn all of this but the chart does not reference a base altitude so perhaps it does not affect the curve?
When I am running matched up to the Power Curves with Fuel Flows per the manual, I feel I am operating within recommended ranges. A quick check of EGT's and things seem to match up intuitively in the 150ROP area so I believe I am leaning in the right area above 75% power. I would just like to use the JPI Lean Find mode properly when above 75%, or so, and can't do it without letting the computer find the peak which means I just ran too lean. Perhaps JPI is behind the curve? Ha, thats a joke. I love my EDM.
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I think you're overthinking this. It's good you're trying to be cautious imho, but here's my 2 cents...

First of all, the engine isn't gonna spontaneously explode if you run MOMENTARILY at peak EGT above 75% power. If the exercise is merely to find your peak EGTs at high power settings, then do it quickly & there you go. Never have to bother again.

But I wouldn't bother in the first place!

Your EGTs are gonna peak at ROUGHLY the same values pretty much regardless of % power. Especially if you're aiming for 150F ROP or 200F ROP or whatever, I would just take your normal 75% power peak EGTs and call it a day.
 
Target EGT

I like the target EGT method. That is, find that temperature for your monitoring setup that is 150 degrees or so ROP and simply stay there with the red knob when WOT up to the altitude or throttle position that you can run LOP.

But you might ask, how do I know what the peak is so that I can pick my target EGT? I spent some time finding peak EGT WOT at 7500 to 8000 feet. That is going to be a little cooler than peak EGT at sea level (not as much as you would think though). If you back off the 7500 peak by 150 degrees you will be more than 150 degrees from the sea level peak but pretty close. Pay attention to fuel flows too.

A little table mounted on the panel of FF for RPM and altitude that keeps you at your target EGT is a great reference that allows your to keep your head outside the cockpit while climbing out. You will also very quickly spot discrepencies (like accidentally being LOP!).

Simply don't go looking for peak at high loads on every flight. Just do it once or occaisionally for your instrumentation setup and at something less than absolutely full power.

I usually use 1300 degrees as the target EGT for full power, down low climbs. I've never seen an EGT over 1500 in any circumstance so I am pretty comfortable that I am neither doing damage or wasting a lot of gas.

The problem with simply saying full rich for full power is that, particularly on expirimental aircraft, with all kinds of non-standard carburators, injection, exhaust and induction systems, there is no guarantee that simply pushing the mixture in all the way is "right". You really have to establish what is "right" for your particular set up.
 
Target EGT

Very good repsonses and I appreciate it.
I assume Target EGT is done off of the first cylinder to peak? My spread is about .6gph, not great, but not bad. I am considering a restrictor in one injector on cylinder #3 that seems to be the offending cylinder as the other three are very close to each other.
Thanks again.
 
Target EGT

There is a good article on "Target EGT" on the GAMI site. You find it by taking off full power at sea level on a standard day. I guess you have to adjust a little if it's not convenient to meet those two conditions. It's apparently intended for leaning in a climb but I don't see why it would not apply to your issue, too.

EGT readings vary with sensor placement and other things. That said, mine is about 1275 and my LOP readings are around 1450 - > 1500. I put a label on the edge of my engine display to remind me. Just trying to be helpful. I really don't know the answer to your original question, but this could provide a good workaround.
 
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