EGT - Lean of peak question

Michael

Michael

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This may sound silly, But it has never been properly explained to me. I have been reading manuals on engine performance, and keep seeing examples like "90% LOP" or "120% LOP". If i understand my guage (see attachment) When I lean the mixture untill it is at peak perforance (which I adjust the red needle beforehand to show), Then keep leaning it..the EGT gauge will drop and then I am runnning Lean of peak? If i enrichen the mixture i would be running rich of peak?
When I was taught during my student pilot days, I was told to pull the mixture untill the engine started to run run rough then turn the knob 3 turns. that would be the proper mixture for cruise and high altitude takeoffs.
Now..I may be all wrong about all of this..so help me here...But, If you look at the picture, When I run at peak, the needle is close to the 16. This is done by the previous method of pulling the mixture untill rough, then adding 3 turns.
So i have always set my red needle to just shy of 16.
Some of the reading I am doing would tell me this is way too high for exaust gas temps. Am I doing this all wrong? Or is my Gauge a little squirly? Or is this normal? What procedures do you all use for leaning your mixture?
 
Engine leaning has become a hot topic in aviation so to answer some of the questions and shed some light on others I am providing the Lycoming SSP700 manual about engine leaning. There is a lot to learn about leaning and what not to do. Please take your time and read the complete article it’s worth it.




​
The “NEW” Old Leaning Technique



There are many “experts” today with new products and techniques to help customers in the operation of their engines. One that is receiving public attention by way of aggressive advertising is a company manufacturing fuel injection nozzles and espousing as operating technique that is “better” than that recommended by the engine manufacturer. The newly discovered method of operating on the lean side of peak exhaust gas temperature has been known since Charles Lindbergh employed it to navigate the Atlantic Ocean and Max Conrad established distance records in his Comanche. This procedure was employed on large supercharged and turbocharged radial engines effectively during the era of large transport aircraft such as the Lockheed Constellation and Douglas D-6. Of course those of you who are knowledgeable about that part of aviation history know that there was a full time member of the flight crew, the Flight Engineer, responsible for engine management. He did not have to worry about flying the airplane or dealing with complicated ATC clearance instructions. There was a full panel of engine instruments and controls directly in front of him, including a detonation monitoring system and, in some installations, a torquemeter to avoid critical operational areas.



Operating on the lean side of peak exhaust temperature (EGT) or turbine inlet temperature (TIT) involves leaning the engine until EGT or TIT reaches a maximum and starts to decline. Theoretically it is the area of the combustion regime that corresponds to best economy (most miles per gallon). Lycoming recommends cruise operation at peat EGT or TIT, which is the point where the best economy range starts. For optimum service life, Lycoming suggest operating 50 degrees rich of peak EGT or TIT. On an engine like the TIO-540-AE2A, this translates into a difference in cruse fuel economy of approximately 2-3 gallons per hour compared with peak or lean of peak operation.



Operating lean of peak results in substantial reduction power output, more that 8% from that obtained with best power fuel flow. If leaning is initiated at 75% power and continued through 50 degree F lean side of peak, the actual power output at that point will be approximately 69%. No wonder the indicated fuel flow shows a dramatic reduction. Although the fuel economy seems attractive, the aircraft cruise suffers. To keep from wallowing through the sky, proponents encourage opening the throttle once leaned to regain lost power.



This is where the plot begins to thicken. There is a big difference between normally aspirated and turbocharged engines when employing this technique. With a normally aspirated engine, if leaning is initiated at 75% power and leaning past peak EGT is accomplished, it is unlikely (but not impossible) to induce detonation by opening the throttle to regain power. In our initial examples, both Lindberg and Conrad were operation engines that had little potential for detonation based on the fuel they were using. A highly turbocharged engine is another matter. Employing this same technique will put the engine into a narrow operating envelope where detonation is possible if the mixture is richened slightly. The only reason the engine does not experience detonation is that the mixture is too lean to support it. At this point, there are a number of factures that can assume control over your engine and cause problems. If the initial leaning is not accomplished carefully it is possible that the engine is not really set at 50 degrees lean of peak where intended. Properly leaning an engine is undoubtedly the least understood too area of power management. Most pilots lean too fast when looking for peak, thus they overshoot. Instead of moving the mixture lever gradually, the exercise becomes a series of rapid movements that ultimately fails to arrive at the correct setting. The best technique to establish peak EGT or TIT is to lean in small increments and allow time for the temperature to stabilize after each lever movement. Continuous movement of the mixture control lever should be avoided since it does not allow for adequate stabilizations time. That there are not more problems resulting from improper mixture control is because considerable margin is built in through the development and certification process. With turbocharged powerplants, the potential for causing engine damage through mismanagement is much grater. Remember that those large radial powerplants used as examples for the lean of peak methodology were cautiously operated at cruise powers of 65% and below where the possibility of bad results was greatly reduced.



During the attempt at power recovery, it is a major assumption that opening the throttle to regain power will not cause a richening of the mixture. Unfortunately, some fuel metering units tend to provide richer fuel schedules as the throttle is opened and manifold pressure is increased. This phenomenon is not discouraged since it helps promote engine cooling at high powers. Sometimes the amount of enrichment may vary from unit to unit. When adding manifold pressure on the lean side of peat TIT, this tendency could be catastrophic if the mixture richens significantly from the original desired set point.



Also, opening the throttle increases the pressure ration across the turbocharger compressor which in turn, raises the induction air temperature and decreases the air density. This decreased in induction air density will effectively result in a richer mixture. The expert says that operating lean of peak safeguards our engine in the event of a plugged fuel nozzle. Apparently, the expert does not understand how current Precision Airmotive Airmotive fuel injection systems really operate. Fuel in metered at the servo, then sent to the fuel nozzle. Plugging a nozzle actually results in sending more fuel to the remaining open nozzles. This essentially richens the mixture and may be enough to move one or more of the cylinders into detonation. Unfortunately, many of these variables are out of the control of the operator who is relying on the premise that this is just a simple leaning technique.



As the last strike, once the engine has been established in the lean of peak condition, and the throttle has been advanced for power recovery, there is no means to confirm that the mixture is properly leaned. The only way would be to richen the mixture to confirm peak TIT. This could move the engine in detonation. It is also not possible to confirm what margin remains between the setting and the onset of detonation. Detonation is not necessarily marked by the characteristic rattling or pinging readily identifiably by the operator. Instead it may be occasional or sporadic but still with the same potential for causing serious engine damage. The lean of peak methodology places strong emphasis on proper pilot techniques, accurate, calibrated engine instrumentation, and does not allow for confirmation of the proper mixture setting. Any lapse in either can be financially costly or worse.



Lycoming is in complete agreement that if is possible to operate an engine on he lean side of peak TIT. I t is don on engines in Lycomings well instrumented Experimental Test laboratory every day. There is noting detrimental in operating an engine in this manner. However, Lycoming can attest to the fact that things that work well in the test laboratory have not always proven successful in service. In the sales literature provided for this “new” technique, it is stated that Lycoming recommended this operational procedure in an owner’s manual that dates back to the late “60’s”. No mention is made why it is no longer recommended on their present engines. That fact is that the technique of operating lean of peak and power recovery was discontinued due to the resulting increase in service issues. Burned pistons, valves, ruined rod and main bearing were traced to the inability of pilots to utilize this technique with the instrumentations and distractions found in the typical general aviation aircraft. If Lycoming felt that this was indeed an efficient and reliable method of operating, you can be sure that it would be in their recommended procedures. Contrary to some beliefs, neither the automotive or aircraft engine manufactures are in secret collusion with the oil companies to drive up fuel consumption. The end customer might be assured that if there is a problem resulting from engine mismanagement, the “experts” with their fuel nozzles and leaning recommendations will not be offering to pay the warranty policy in the event of a problem, the answer came back that this is regarded as a “improper operation of the part of the operator”. If you have a problem resulting from operation according to the expert’s recommendations he does not intend to cover your repair or replacement costs.



Lycoming piston aircraft engines are rugged and withstand a lot above and beyond their normal operating requirements. The operating procedures that Lycoming recommends combined techniques that have been found to promote good engine service life and accommodated normal pilot skills. Lycoming does not custom design operations instructions for each pilot skill level or individual aircraft based on instrumentations. Today, pilots must contend with higher traffic levels and more complex ATC demands that reduce the attention time for powerplant management. Electronic engine controls that are currently being developed will allow operation in ranges not feasible today due to full time computer monitoring. In the meantime when one of the “experts” tells you how to operate your engine better that what the factory recommends, exercise extreme caution. It’s easy for someone to recommend new techniques whey they have no obligation to cover the warranty or out of pocket cost if there are problems down the road.



Operating an engine “on the edge” is possible provided the pilot is extremely precise, has good instrumentations, and monitors the engine condition full time. For 98% of the pilots, it is an invitation to potential trouble. It only takes one brief episode of mismanagement to incur deep internal damage that will cost money later. Most people do not even realize when it happens since the engine continues to operate without any sign of distress. For a highly turbocharged engine, the supposed fuel savings amounts to $4.00-6.00 per hour. Considering the total operating expense for a high performance aircraft, is the small saving if fuel cost worth the price of an engine? You do not need to ask the “expert” for help with that one.





Experts are Everywhere to help you

Lycoming SSP700

Posted by Stache
 
Slowly pull out your mixture, giving your egt time to settle between turns. It will reach peak egt and then start to drop as you lean more. At its hottest point its at peak egt. If you richen from that point you are rich of peak. If you lean from that point you are lean of peak. The individual cylinder tempertures can vary by quite a bit so even though the egt for your one cylinder reads lop it doesnt mean that the others are. Be advised, the same things are not happening in the motor 50 degrees rich of peak as 50 degrees lean of peak even though the egt needle is in the same position. Peak power (highest combustion chamber pressure and highest cht's) occurs at somwhere between 100 degrees rop and 50 degrees rop. Lycoming says you should not lean your Lycoming io-360 variant at power settings above 75%. At 50 degrees lop your cht's and combustion chamber pressures will be significantly lower, as will your power output. Conventional wisdom is becoming that cruising lop in normally aspirated engines is the way to go as your motor runs cleaner, cht's are lower lengthening cylinder life, and you use less gas. There is a technique to it. Its well described by John Deakin on Avweb, the Pelican Perch articles. Be advised, Deakin is in with the Gami crew who's business it is to sell you gami-jectors. Also, be advised that Lycoming and Continental are not necessarily on board with these techniques. You can find a letter about it on Lycomings web site. Do a search for "there are experts everywhere" and it'll pop up.
oops..Stache got it fer ya already.
Best thing to do is read Deakin's articles and decide for yourself. Stache may know differently, but I dont think you can damage a normally aspirated motor by running it well lean of peak, even at high power settings. The motor just wont make the power and heat at such lean settings to damage itself. The problem occurs when you inadvertantly lean to near best power while running at a higher than 75% power setting, like leaning to best power while on takeoff and climbout. You can get a general idea of how much strain your placing on the motor by noting the cht's. I'd be curious to know if anyone knew what the "ideal" cht would be.
 
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Blank stare wouldve worked too. Alot of information in that first post, most of which i have no clue as to what they are saying. I am not a mechanic.
But appreciate the help.
 
Michael:

I routinely run my engine LOP on long cross country trips. I have a turbonormalized A-36 with the io-550 engine. My plane is equiped with a graphic engine monitor that shows the egt and cht for each cylinder along with TIT. What GAMI jectors do is measure and distribute the fuel flow to each cylinder more precisely. In my plane, as I lean from a point rich of peak, each of my cylinders will reach peak EGT within a fuel flow of .5 gallons per hour. Put another way, one cylinder after another will go LOP as I reduce mixture; all cylinders go LOP within 1/2 gallon of fuel flow. Most factory fuel injectors have much wider spreads.
Be careful, LOP operations mean all cylinders are operating LOP. Many folk lean until the first peaks and goes lean and other cylinders may be operating rich of peak (ROP). This is very hard on the engine. Unless you have very precise fuel flows and a manner in which to measure the performance of each cylinder, it's very difficult to properly operate in this manner.

In my case, I can greatly extend the range of my plane operating LOP. I've cited several examples on this board and others where LOP operations were effectively used to extend range as much as 15 to 25% over what rich of peak operations would be (this would be at lower power setting).

Best,

Dave
 
Cricketts, the sound of silence, ie, no response. Pretty funny, Michael.


Michael, you come out here and I can show you the graphs of what is going on in your engine when you fuss with the red knob.
 
rereading the first reply,
New question...Say i lean the mixture LOP. and then start a descent, as the manifold pressure rises, and I have not changed the mixture, Could I be in danger of detonation?
would this be the same as adding power? I ritchen as I descend, but never thought about the mixture first.
 
Michael said:
rereading the first reply,
New question...Say i lean the mixture LOP. and then start a descent, as the manifold pressure rises, and I have not changed the mixture, Could I be in danger of detonation?
would this be the same as adding power? I ritchen as I descend, but never thought about the mixture first.
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I'm not sure if you have a turbo or not?

This is what we do...we are at 8000 full mp, full rpm, 50 LOP (you need a JPI or equ to be safe-your richest cylinder on the lean side needs to be 50 LOP in other words all other cylinders are leaner)

We back off the rpm to like 2200 and the mp just a little bit, mixture stays. As we decend we keep the mp value the same. This keeps the engine percentage power lower than 75%...prob more like 50-60%.
 
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Richard said:
Cricketts, the sound of silence, ie, no response. Pretty funny, Michael.


Michael, you come out here and I can show you the graphs of what is going on in your engine when you fuss with the red knob.
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Richard, I have spent another hour reading more on the subject and have learned that everyone seems to have their own way of leaning. I am more confused now than before. I will take you up on that offer. When is a good time for you? I can fly out there Sunday..weather permitting.

on a different note: did you see the clouds buildup out there Sunday morning? I walked out of the hotel (Santa Maria) 8am, clear skies, got fuel, breakfast...9am scattered clouds now. Took off at 10am, with broken skies, controller was heard telling another Aircraft they were updating the condition to overcast. got outta there just in time. I thought the clouds were present in the morning and disipated by noon. That was kinda weired.

Michael
 
Michael said:
rereading the first reply,
New question...Say i lean the mixture LOP. and then start a descent, as the manifold pressure rises, and I have not changed the mixture, Could I be in danger of detonation?
would this be the same as adding power? I ritchen as I descend, but never thought about the mixture first.
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In a N/A engine running LOP, the power output will actually drop off as you descend if you leave the engine controls alone and you can't hurt the engine that way. It may start to run rough as the mixture leans out, to correct for that, usually you can just close the throttle a bit but you may need to push the mixture in a bit as well. Something that works pretty well in a descent (or climb for that matter) is to move the mixture to keep the same EGT as you change altitude.
 
Michael, a warm front moved through...slowly. This late in the season and we're still getting rain. In fact, this morning the coast was hammered by isolated +RA and inland across the coastal range was even getting some. This aftn I saw some really impressive build ups out over the ocean maybe 20-30 nm off shore, maybe up to 30,000.

That wx you experienced at SMX was coming up from the south. 15 minutes flying time north was CLR and temps in the lo 80s. SMX is at a curious place, a meeting place for diverse localized wx. It's not unusual to have 0/0 FG, CAVU, 018 BKN-OVC, CAVU, FG all in one day. What were the sfc winds?

(Edit) The morning clouds dissapating by noon...you're thinking of the marine layer. No sign of that yet, it's a summer thang. Our winters are like most folk's summers.


This Sunday sounds fine. I'll take you to a nice lunch and what not. How early/late can you arrive/depart?
 
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Richard said:
This Sunday sounds fine. I'll take you to a nice lunch and what not. How early/late can you arrive/depart?
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Sounds like a plan. I can arrive as early as 10 and depart as late as 4..weather permitiing.
Thank you Richard. I really want to understand this better. Now I am paying for overhauls :dunno:
 
Here is an ironic story.

As an 18 year old student, I was taught to lean until rough, then twist two turns richer.

As a 40+ private pilot, I bought an airplane, went to school on LOP operations, learned that I had to have GAMIjectors, learned that I had to have a JPI engine monitor (or one like it), paid large sums of money to get all that installed, and very carefully went to work running LOP.

The results were stunning! As Dave said, range is the number one thing gained...I went from 16gph (go far) and 20gph per side (go fast) to 12gph (go far) and 15gph (go fast).

My TAS is equal either way but the fuel burn is much less! In addition, I rarely need to add oil. Before, running ROP, I would burn a quart in 2-3 hours. Now, I burn a quart in 7-8 hours. The engines seem happier, LOP life is great!

Here's the ironic part. Now that I know my airplane here is how I lean:

At the first level off, I simply do a BMP (Big Mixture Pull) to the '3' label on the throttle quadrant...and slow down there...continuing a millimeter or so until the engine gets rough. I then push it forward a millimeter. I repeat for the other engine.

After a moment or so, I look at the JPI's TIT reading and it is usually between 1620 and 1640. I tweak it with the smallest movements possible to exactly 1620 (if necessary).

So all the expense and schooling just to do what I was taught as a student.

(Of course, the JPI is mandatory...because if a plug fails on a cylinder or something starts to develop trouble, LOP will KILL a jug in no time flat.) So, the money for the equipment was not a waste.

I now do my mag checks in flight (in addition to on the ground), while LOP. Going to one plug will instantly cause the temps to shoot through the roof!!!!!! So it is impeartive to have an engine monitor -- and do this mag check often (albeit quickly ;) ) to make sure all your plugs are OK.

I chuckle everytime I do it (lean till rough and slightly enrichen) though, because those old pelicans were smarter than anybody knew...
 
RobertGerace said:
The results were stunning! As Dave said, range is the number one thing gained...I went from 16gph (go far) and 20gph per side (go fast) to 12gph (go far) and 15gph (go fast).

My TAS is equal either way but the fuel burn is much less! In addition, I rarely need to add oil. Before, running ROP, I would burn a quart in 2-3 hours. Now, I burn a quart in 7-8 hours. The engines seem happier, LOP life is great!
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This is a really good example because with the 5gph savings that would completely pay for a factory reman engine and prop overhaul. (5*3.5*1700~$30,000). To sell LOP they should say receive a free engine for using LOP during your flight :yes:
 
Iceman said:
This is a really good example because with the 5gph savings that would completely pay for a factory reman engine and prop overhaul. (5*3.5*1700~$30,000). To sell LOP they should say receive a free engine for using LOP during your flight :yes:
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'cept IME the savings are nowhere near 5 gph on a pair of IO-470's. If you compare operation at 100 ROP with 50 LOP and no changes to MP or RPM then you do see those kinds of "savings". Most of us flying ROP are more likely to be somewhere between 30 ROP and 50 ROP which already saves a big chunk of that 5 gph. Then there's the drop in power and associated loss of TAS which cuts the savings in half again. In my airplane when you reset MP and/or RPM to restore TAS, the difference between 30 ROP and 50 LOP amounts to about .5 gph per engine or a total of 1 gph. Of course with gas running over $3/gal, that's a $3/hr saving and nothing to sneeze at. Besides the engine does run 30-50 F cooler CHT wise and as Robert indicates it seems to run cleaner.

Now that's without turbochargers. A boosted engine may require a richer mixture to stay cool at high altitudes than I use and that can make LOP quite a bit more efficient.
 
lancefisher said:
'cept IME the savings are nowhere near 5 gph on a pair of IO-470's. If you compare operation at 100 ROP with 50 LOP and no changes to MP or RPM then you do see those kinds of "savings". Most of us flying ROP are more likely to be somewhere between 30 ROP and 50 ROP which already saves a big chunk of that 5 gph. Then there's the drop in power and associated loss of TAS which cuts the savings in half again. In my airplane when you reset MP and/or RPM to restore TAS, the difference between 30 ROP and 50 LOP amounts to about .5 gph per engine or a total of 1 gph. Of course with gas running over $3/gal, that's a $3/hr saving and nothing to sneeze at. Besides the engine does run 30-50 F cooler CHT wise and as Robert indicates it seems to run cleaner.

Now that's without turbochargers. A boosted engine may require a richer mixture to stay cool at high altitudes than I use and that can make LOP quite a bit more efficient.
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Yeah your probably right. We normally see about 2 gph less with 50 LOP with sim IAS. However we normally never run 30 ROP especially if the power is above 60%. It is usually 55-65 ROP when we have high power settings. However 2*3.5*2000= $14,000 which is still a good distance towards an overhaul.

Your right about the turbochargers...Lancair 400 people are getting amazing speed out of 17-18gph using LOP 50-80
 
lancefisher said:
Something that works pretty well in a descent (or climb for that matter) is to move the mixture to keep the same EGT as you change altitude.
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I would not advise blindly assuming that peak EGT remains at the same temperature at different altitudes. Might be my Mooney's EGT installation, but I've noted that indicated peak EGT temperature changes significantly with altitude. Peak is usually 50-100 F degrees lower at high altitude. Mind you, I tend to use the whole airplane, so "at high altitude" may mean EGT temperature at 16-17k versus 4-5k. If I set the little red needle to indicate observed peak EGT at 5k and then assumed it would be the same at 16k I could be 100+ degrees F LOP at what I assumed was peak EGT. Lean 100 F degrees further LOP and you are operating 200 F degrees LOP and way, way reduced power. The IO-360 is power limited enough at that altitude without handicapping it further. OTOH, if you made the assumption but tried to shoot for 50 F degrees ROP you could end up operating at peak EGT, not ROP.
 
Michael, some rambling general thoughts:

Even the snake oil salesman (Mr. Deakin) will tell you don't try LOP with a single point EGT; in that respect he is in complete agreement with Lycoming. Since you have a single point you are ignoring all information sources if you operate LOP.

Running ROP with your engine/EGT installation requires setting power (throttle & prop), giving things a minute to stabilize (Your Mooney can take several long minutes to settle at final cruise speed), then slowly adjust the mixture. As Lycoming notes, small discrete moves of the red knob are better than a continuous movement. My general method is to pull continuous until very close (100 F degrees below peak), then switch to discrete moves of the red knob to cross peak. You will find that the EGT needle doesn't seem to react for a goodly portion of the red knob pull, then starts to move fairly rapidly. The shift from "dead" to moving quickly is where I switch to discrete micro movements of the red knob. I find it is actually easier to find peak EGT from the lean side--IOW, cross peak (watch the needle/listen to the engine) and then enrichen to return to peak. LOP is more notable by the rumble felt in soles of your feet (put them flat on the floor) than any other method. I lean until the needle peaks and my feet tell me the rumble has started, then reverse to richen the mixture. The EGT will usually peak and the rumble will stop. Note the EGT reading and then go 50 degrees ROP (again, very slow, discrete movements).

Forget that the little red needle on your EGT gauge even exists. See my reply to Lance regarding peak EGT changing with altitude. At every altitude lean by actually observing peak EGT, not by assuming the red needle marks the correct spot.
 
Interesting guys. There are some different things to consider. A turboed aircraft will maintain sea level power up to FL180 or higher--much different considerations. With GAMIs and an graphic engine equalizer; you are much better equipped to experiment with LOP and know exactly where each cylinder is performing. With a single EGT/CHT probe and factory injectors, you only know the performance of one cylinder and factory injectors aren't as easy to run LOP--in general.

I flew a P-Baron yesterday, and whether ROP or LOP, adjusted my power setting to keep the hottest CHT at 380 or less in cruise. At 14,500 feet, 2400/34, we were able to run LOP at just over 14 GPH per side and trued out just over 190. Bringing the engines ROP and keeping CHTs at 380 lead to a TAS just over 210. I realize these are different power settings, but a 20 gallon per hour change is fuel burn produced a significant difference in cruise speed and range. So, some of this depends on what you're trying to do and what you're flying. We know that you're getting the most energy per gallon of fuel LOP. ROP, we have excess fuel during the burn. So, what are you trying to accomplish--go far or go fast?

Lance reduces his power ROP to extend range. We've discussed the benefits of ROP v. LOP at settings that produce the same airspeed. I did some tests that showed in my TN A-36 it was very beneficial to run LOP. Lance doesn't get nearly the same benefit in his NA Baron.

Perhaps at Gastons this year, we can come up with some flight tests and fly in a couple of different planes (for those as anal about this as a few of us seem to be) to graphically see what the differences are. I can also download the data from the JPI and graphically show where EGTs, CHTs and TIT are in flight; if anyone would find that interesting. Could run ROP and LOP at to the same CHT temp or same airspeed and graph the results.

In the A-36, the problem I had comparing ROP and LOP at the same airspeed, is I couldn't get to higher power settings ROP without using a LOT of gas. I could run 75 to 80% power at 16 gph LOP. That trued me out at about 180. I had to reduce MP way down to get to the same airspeed ROP and burn over 25 gph.

Be interesting to run some 'xperiments at Gastons if anyone's interested.

Best,

Dave
A-36TN ADS
 
Just like the infomercials, I need to add the disclaimer that 'My results are not typical' but they are my results and I've checked them many times.

As to EGT and altitude, I have seen many different numbers and they seem to have a mind of their own. I adjust everything to ensure that CHT never goes higher than 380 on the hottest jug, and TIT never goes above 1630 for any period of time.

I don't really care what is happening with individual cyl EGT other than for trend information (and problem diagnosis) -- but my point about EGT temps is that I don't have a target that I try to arrive at.

In 99% of cases, I'm right at 14.5 to 15.0 gph (per side) and truing between 195 and 205 depending on the variables.

I forgot to mention in my post above that I also push MP up to redline after I go LOP (and in my airplane that is 32"). (30" is the top of the green.)

Now...about savings...

Before the GAMI's and JPI, I used the Jerry Temple method of leaning which was to lean to 100pph and make sure the TIT doesn't to above 1550. (This put me right about 16-17 gph per side. I have no idea if that was ROP or LOP -- I didn't know enough then to ask.

So -- with that information -- my savings is only between 1 and 2 gph per side -- and this is much more in line with what the collective wisdom says.

EXCEPT that when I put in the GAMI's and JPI, I went up and tried the Temple method and quickly exceeded redline TIT (1650). I was quite worried about it, and went to a LOT of trouble to make sure my TIT readings were accurate. I had the Alcor TIT gauge replaced, and I had the A&P calibrate my system (twice). The only way to get book speed and not exceed 1650 TIT was to run at 20gph per side. This is higher than book fuel burn, and I don't know why my airplane was producing those numbers -- which are clearly not the norm. Nevertheless, certain that the readings were correct...

With new Alcor and new JPI (oh yes...a new exhaust system as well...all at the same time...sigh) It took about 20gph per side to get book TAS (195-205) and stay below 1650 TIT.

So, given the above, I count my savings at 5gph per side. (I wish I had the time and money to only make one change at a time -- to isolate what caused the change; but I don't...'while it is in' I need to get stuff done...sigh.)

Given the above, I'm saving 10gph and that is $40/hr based on the price of fuel at the airports I frequent. That goes a long way towards buying new engines at TBO.

I am as certain as I can be that the TIT and CHT values are correct, and I watch the JPI like a hawk. There is a lot of science about how hot the metals can get, and how quickly they can cool, and I study it, and operate my airplane by it.

Despite the above, the naysayer's say that I will burn my engines up.

I hope they are wrong. ;)
 
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Ed Guthrie said:
I would not advise blindly assuming that peak EGT remains at the same temperature at different altitudes. Might be my Mooney's EGT installation, but I've noted that indicated peak EGT temperature changes significantly with altitude. Peak is usually 50-100 F degrees lower at high altitude. Mind you, I tend to use the whole airplane, so "at high altitude" may mean EGT temperature at 16-17k versus 4-5k. If I set the little red needle to indicate observed peak EGT at 5k and then assumed it would be the same at 16k I could be 100+ degrees F LOP at what I assumed was peak EGT. Lean 100 F degrees further LOP and you are operating 200 F degrees LOP and way, way reduced power. The IO-360 is power limited enough at that altitude without handicapping it further. OTOH, if you made the assumption but tried to shoot for 50 F degrees ROP you could end up operating at peak EGT, not ROP.
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You're right, I was thinking of operations in the 2000-10,000 MSL range. Peak EGT definitely drops off as you go higher without a turbo. I don't know if this is the result of the lower ambient temps, the thinner air, or both. The main point I was trying to make is that during a descent or climb while running LOP, if you maintain constant EGT, you shouldn't cause any harm in a normally aspirated engine. During LOP operations, the available power output is pretty much a function of the amount of fuel fed to the engine.
 
Ed Guthrie said:
At every altitude lean by actually observing peak EGT, not by assuming the red needle marks the correct spot.
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That I can agree with, although the absolute EGT can be useful for quickly getting close.
 
RobertGerace said:
J
EXCEPT that when I put in the GAMI's and JPI, I went up and tried the Temple method and quickly exceeded redline TIT (1650). I was quite worried about it, and went to a LOT of trouble to make sure my TIT readings were accurate. I had the Alcor TIT gauge replaced, and I had the A&P calibrate my system (twice). The only way to get book speed and not exceed 1650 TIT was to run at 20gph per side. This is higher than book fuel burn, and I don't know why my airplane was producing those numbers -- which are clearly not the norm. Nevertheless, certain that the readings were correct...
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Bob, that's consistent with my (limited) experience using turbocharged engines. It's often necessary to waste a lot of gas keeping the temps under control and running LOP is the right way to do that efficiently IMO. And when you compare the fuel burn with those excessively rich mixtures ROP with LOP flows you will see a significant improvement in gas mileage at the same airspeed.


Despite the above, the naysayer's say that I will burn my engines up.

I hope they are wrong. ;)
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Heck, with what you've had to spend so far, I would think the price of an engine replacement would hardly be noticeable:p.
 
Robert:

Aren't you running the IO-520 engines on there? Are they the WBs? The P-Baron I'm looking at has these and I'd love to compare numbers and perfromance if you're running the same engines. The Baron will be a little heavier plane than yours, but it would be interesting to run some comparisons at the same altitude (DA or PA) and power settings.

Best,

Dave
A-36TN ADS
 
Dave Siciliano said:
Robert:

Aren't you running the IO-520 engines on there? Are they the WBs? The P-Baron I'm looking at has these and I'd love to compare numbers and perfromance if you're running the same engines. The Baron will be a little heavier plane than yours, but it would be interesting to run some comparisons at the same altitude (DA or PA) and power settings.
Click to expand...

And don't forget that the bleed air for the cabin costs some power.
 
lancefisher said:
Heck, with what you've had to spend so far, I would think the price of an engine replacement would hardly be noticeable:p.
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Lance,

Thanks! I needed a good sanity check on this.

Regarding the $$ thank GOD it has slowed way down. :goofy: I have a 100% dispatch rate, and zero squawks (because I fix the new one that shows up every flight as it happens, sigh)...

They aren't major...but a rebuilt strut here...and new corrigated bellows there...I think this is just normal twin Cessna stuff now...and nobody said that was cheap.

Now I'm trying to figure out: do I run these engines to TBO and sell it as a runout and upgrade...or do I stick RAM's on and true out at TWO-HUNDRED-AND-FORTY KNOTS!!! (http://www.ramaircraft.com/Business-Transportation/T310/BT-T310-IV.htm ) OH MY GOD!

...OR...do I upgrade to a CJ (I don't think I get enough value out of a 400 series Cessna given the loss I'll take on the 310).

Much depends on God's grace.
 
Hey Bob:

Are you running IO-520s in your plane? WBs? It would be interesting to compare your numbers to those in a P-baron I'm flying if your set up is similiar. Perhaps we could compare power settings, speed and fuel flows ROP and LOP in the two birds.

Best,

Dave
 
Dave Siciliano said:
Robert:

Aren't you running the IO-520 engines on there? Are they the WBs? The P-Baron I'm looking at has these and I'd love to compare numbers and perfromance if you're running the same engines. The Baron will be a little heavier plane than yours, but it would be interesting to run some comparisons at the same altitude (DA or PA) and power settings.

Best,

Dave
A-36TN ADS
Click to expand...

Dave,

Let's race! That would be cool. :D

Seriously, I outrun many airplanes, but I can't seem to outrun the Baron's. I know the Jag that I flew was a little slower -- actually faster in the climb but just slightly slower in cruise -- but that was NA. I have to imagine that it would be a close race!
 
Dave Siciliano said:
Hey Bob:

Are you running IO-520s in your plane? WBs? It would be interesting to compare your numbers to those in a P-baron I'm flying if your set up is similiar. Perhaps we could compare power settings, speed and fuel flows ROP and LOP in the two birds.

Best,

Dave
Click to expand...

I have TSIO-520-B's with GAMI's.
 
You're quite a bit lighter than me I believe. Gross is 6,200 on the P baron. I also am using some of the power for the pressure vessel; AC and any other accessories. These engines are rated at 325HP for a couple of minutes, then one has to reduce power. Altitude would probably make a difference. I believe my cabin has a little larger profile.

The book shows the P begins to outclimb the NA B-58 after 3,000 feet. Shows 1,500 fpm all the way up; whereas the NA begins climbing at 1700 and decreases to 900 fpm at 10,000. The NA takes off in a shorter distance that the 58P until ISA is 4,000 feet; then the P has better numbers.

We'll have to compare book numbers at some altitude and speed and see if we can prove 'em up. ;)

Dave
 
Dave Siciliano said:
I believe my cabin has a little larger profile.
Click to expand...

I think that you'll find that the Baron max cross section has less area than the 310's. IIRC the 310 is about 4 inches wider and at least as tall as a Baron.
 
RobertGerace said:
I have TSIO-520-B's with GAMI's.
Click to expand...

Although Deakin the Guru of LOP says not to, I run the T210 GAMI'd TSIO-520 at 65% power LOP using the OEM single point CHT and a new TIT gauge for which I personally selected the thermocouple point near the entry to the turbocharger [the original Cessna EGT gauge on this aircraft was on cyl. #3, and there was no TIT gauge, and no provision in the service manual for installing one]. Deakin wants you to run wide open throttle and 6 point monitoring. Cessna says you can run any mixture at 65% power without harm to the engine.

I have used the TAS comparison that Dave Siciliano discussed, which is the only way I know to obtain an apples-to-apples comparison. I obtain 162 up to 182 knots TAS, depending on altitude and OAT at the 65% power setting, and burn 81#/13.5 gph LOP which is consistent with Deakin's formula for that engine. The fuel savings amounts to about 2 gph. But after 500 hr. of this on an overhauled engine [Millenium cylinders], I think the "cleaner/cooler" factor may be more significant to engine life/cost factor than the fuel savings cost. I had the iridium plugs installed on overhaul, and have cleaned them twice [solvent, not blasting] in the 500 hr. I typically need not add oil during the 25 hr. between oil changes [which worried me originally], but fill initially to 9 qt. rather than the 10 qt. allowed.

I also found engine baffling to be the biggest source of problems in cooling on this aircraft.

If you're going to run LOP, first read and understand Deakin's columns. He has two engine management series, the initial one was based on his normally aspirated experience, and the second on turbonormalized experience. Note that there is a significant difference in operating techniques between the aftermarket turbonormalized and the OEM turbocharged engines.

Know your aircraft.
 
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Ahhh Lance!! The potential race becomes more interesting!! So my cabin may be a little smaller in cross section, but I've still got some things bleeding off power and am heavier with the pressure vessle--that right?
Robert:
What kind of horsepower and time on those engine?

Dave
 
285 per side...about 900 hours. After I put my RAM's on I'll be 325 per side and Zero time..lol... If I can't beat you now, maybe then... ;)
 
Dave Siciliano said:
Ahhh Lance!! The potential race becomes more interesting!! So my cabin may be a little smaller in cross section, but I've still got some things bleeding off power and am heavier with the pressure vessle--that right?
Click to expand...

Of course if Bob starts pulling ahead you can always raise the cabin and put on the nose hose.:D Might be harder to deal with the excess weight, but I suppose you could leave the tanks empty and remove most of the seats when nobody's looking.B)
 
Bob:

Sounds like a before and after deal to me. This year as is and next year a rematch ifn you don't win!! :rolleyes:

Only problem is, I may not be checked out in the new plane in time for Gastons this year. We'll see.

Gotta see how we're going to do this. I probably won't land on the grass strip in the P-Baron.

Best,

Dave
 
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