Does anyone here routinely run a TCM TSIO-360 Lean of Peak (LOP)? How do you do it and what kind of numbers do you see??
I've done a GAMI Lean Test on stock TCM injectors, and the peak spread at 10,500', 30", 2400 rpm (about 65% power) was from 10.6-11.4 gph. The engine runs totally smoothly all the way down to about 9.6 gph, when it begins to show a bit of roughness.
I also would like to hear from someone who really do this kind of leaning on a steady basis!GAMI obviously has reasons to say that this is safe as well as good for our engines but some real life user of this method is probably useful.
Don't need to say that someone must have GAMI Turbo injectors (TurboJectors as GAMI names them) in order to do it (run LOP) safely.I think that Continental itself also comments the same, plus never run LOP unless 65% power at the most,even with GAMI instaled.EDM 800 from JPI with percentage HP and fuel flow or any other engine monitor is a must in order to do it right and get the most out of it,according to my opinion.
Despite all articles we have read,in our Turbo Arrow III with GAMI TurboJectors installed is only me who actually done it a couple of times. The other 3 folks I share the plane with,are rather too sceptical about LOP operation.I can't recall right now the actual settings I used when I flew this way but I was planing one of these days to do it once more any way.
I'll let you know how it went.
I have a Turbo Arrow IV. I don't run LOP. There are a number of reasons:
1.) I don't have GAMI injectors.
2.) I don't have the fuel flow option on my EDM-700 monitor. So there's no way for me to effectively determine the exact GAMI spread on my engine. Without the spread data, I can't order GAMI injectors and expect them to work very well.
My TSIO-360 will run with all cylinders LOP, according to the EDM-700. However, the last cylinder to peak can only get to -10 dF LOP before engine roughness starts. At this point, the first cylinders to peak (leanest) are down around 80-90 dF LOP.
While I'd love to install fuel flow and GAMI injectors and run the engine LOP, right now I just don't have the budget.
However, be careful when you're using an EDM-800, or the Piper power tables, to calculate the percentage of power produced by the engine. Piper's POH for the T-Arrow definitely contains some inaccuracies with regard to engine power settings, and that's the data that the EDM-800 will use. Specifically, if you look at a T-Arrow POH power chart, it will specify that if you want to maintain 65% power, you should use IDENTICAL MP and RPM settings from sea level to FL200.
That's nonsense. As you climb higher, exhaust backpressure and turbo compressor discharge temps will change. So the higher you are, if you're holding a constant prop RPM, you need to DECREASE MP if you want to maintain a constant power percentage.
Look at the charts for the Seneca II (TSIO-360-EB) and the Mooney 231 (TSIO-360-LB or -MB). Virtually the same engine, but those charts show that you must reduce MP by a few inches between sea level and FL200 if you want to maintain a constant percentage of power, assuming you hold the RPM constant.
Bottom line: Aviation Consumer says that at 14,000', what "the book" says is 75% power is really more like 83% power. Which explains, perhaps, why so many T-Arrow owners must do top overhauls long before TBO. I think many of us are running our engines too hard without realizing it.
Therefore, I use the Seneca II power charts. And when I do get GAMI injectors and run LOP, I plan on using 55% power according to the Seneca II charts. So it'd be impossible to hurt the engine.
While I haven't seen this happen myself, I have heard from numerous respectable sources that the TSIO-360 is particularly ill-suited to LOP operation, especially at higher altitudes, due to the altitude-compensating fuel pump. As you set power and then lean LOP, the system can start 'bootstrapping', which will increase your fuel flows right into the 'red box' which the Advanced Pilot Seminars people talk about.
Even the APS guys -- who are fanatic about LOP operations -- admit that not all fuel-injected engines are suitable for LOP ops. The TSIO-360 is the prime candidate on that 'unsuitable' list.
So I just run 65% power, temperature-corrected, and I set the mixture to 100 ROP on the first cylinder to peak. Cylinders 5 and 6 run about 100 ROP, cylinders 3 and 4 run 150 ROP, and cylinders 1 and 2 run 200 ROP. That's typical for the TSIO-360, given the uneven air induction system it is cursed with. Even if I can't run LOP eventually, I hope that installing GAMI injectors will at least allow me to tighten that temp spread, so that all cylinders are 100 ROP instead of having some at 100 ROP and some at 200 ROP.
Don't do it unless you like changing cylinders. We have the TSIO-360FB and run it 50 degrees ROP. This years annual our compressions are perfect. Last years annual where the previous owner always ran LOP had to change 3 cylinders. There are plenty who will tell you that LOP is great and they run 9 GPH. I've never seen it in our bird even when we set it LOP to see what the temps would do. 50 degrees ROP hits 310-360 CHT and around 1450 TIT, 12 GPH at 10-12,000 altitude. I'm not a proponent of LOP with these small planes. And we have the GAMI injectors, intercooler and EDM-700.
Edited 1 time(s). Last edit at 11/04/2008 04:22PM by turbokurt.
I'm surprised at the disparity in your EGT temperatures. I have a Turbo Plus intercooler on my Turbo Arrow's TSIO 360 FB with 1700 hrs. My EGT's are within 40 degrees F of each other @ 65% power at all teen altitudes (stock injectors). I run 75 degrees rich of peak.
Edited 1 time(s). Last edit at 11/04/2008 04:28PM by Bill L.
For the last three years of my engines life I ran it LOP (TSIO-360) it has just recently been disassembled for overhaul. Naturally I was curious how the cylinders and pistons looked, and the mechanic said they looked great no detonation damage no heat damage nothing. In fact he thought the whole engine looked good (which made me rethink my overhaul decision, but that’s another story)
My engine was completely stock and would just make it to 40/50 LOP on the stock Alcor gauge before it started to run rough. Of course I only ran the engine at 60 percent! It’s been my understanding that at that power level you could pretty much run it anywhere and it would be alright.
My engine was high time which is why I figured I would give it a try. Plus there has been quite a bit of information out there about running LOP that in my opinion made sense.
Engine at time of overhaul was about 1900 hours on an F model.
If the new engine runs the same after its broken in I’ll be running it that way.
turbokurt Wrote:
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> Don't do it unless you like changing cylinders. We
> have the TSIO-360FB and run it 50 degrees ROP.
Not to open a can of worms, but the data from the Advanced Pilot Seminar guys shows that 50 ROP is the *worst* place to run an engine. You either want to be 100 ROP or richer, or you want to be LOP.
50 ROP (EGT) is right where the internal cylinder pressures are at their highest. Same for CHT.
Bill L Wrote:
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> I'm surprised at the disparity in your EGT
> temperatures. I have a Turbo Plus intercooler on
> my Turbo Arrow's TSIO 360 FB with 1700 hrs. My
> EGT's are within 40 degrees F of each other @ 65%
> power at all teen altitudes (stock injectors). I
> run 75 degrees rich of peak.
Remember that the actual raw numeric values of any cylinder's EGT are irrelevant. Your EGTs could be numerically within 40 degrees of each other, but what matters is each individual EGT's value in relation to peak.
In other words, you could have a tight numerical spread but a very wide spread relative to peak. Or vice versa.
What you want to do is run a lean test on your engine. Set it up at 65% power in cruise. Then put your JPI into lean find mode, but use the LEAN of peak mode. The EGT bars will invert as you start leaning.
Lean as far as you can until the engine runs rough. Let it stabilize for a few seconds, and then enrichen back to your normal 75 ROP.
Download the data and plot at what temp each cylinder peaked. THEN you will be able to see: in cruise, when the leanest cylinder is 100 rich of its peak, where are the others in relation to their peaks? Remember, EACH cylinder will have a unique peak value, which may be quite different from the next cylinder's.
Don't worry about the 'spread' between individual EGT values. Look at the spread between the PEAKS of each cylinder's EGT.
I've owned a Seneca II for 9-1/2 years. The first thing I did after purchasing it was to install a JPI 760. I then spoke to the local Continental field tech. He said you can't hurt anything below 65% power - you can run peak all day long at or below 65% power. I am still running stock injectors.
I experimented with the lean find function. After a few hundred hours I came to the conclusion that I basically lean to engine roughness and then add back a tenth or two (gph). This has me flying between 9 and 10 gph. I fly 2300 rpm and set the MP based on the power chart (typically 30" +/- 1.5").
I normally see 380 to 390 degrees CHT on #2 (the highest reading because it is the spark plug - the shop says this position reads 20 to 30 higher than the boss on the underside of the jug), and mid 1400's EGT and low 1500's on TIT. The other cylinders all show 350 and below. I get 165 to 172 TAS depending on altitude (normally between 8000 and 14000), temperature, and weight.
In February 2005, I found metal in an oil filter at oil change time. I decided to O/H. The shop found no evidence of any problems with pistons, cylinders, valves or heads. The engine had around 2500 hours total time and around 2000 since a top overhaul. I had flown the airplane for around 770 hours at this point - probably over 500 hours as described above.
The other engine was overhauled in 2001 with around 2200 hours. I had flown it for around 400 hours. Probably 200 hours were as described above. Same report from the shop - no evidence of combustion related problems.
I experimented with 75% ROP. I got cooler CHT's but TIT was pushing the limit at over 1600 (never mind the higher fuel consumption), and a few knots higher airspeed. I settled on 65% LOP as described above.
...easy decision.
Edited 1 time(s). Last edit at 11/05/2008 09:25PM by breymond.
I have a 75 Seneca II with GAMIs and a JPI 760 with fuel flow. The airplane has only 93 gallons usable fuel. I went to the Advanced Pilot Seminar about a year ago and have been running LOP since then. I typically run about 28" MP and 2400 RPM, and about 30 - 40 deg LOP. This delivers 9.1 or 9.2 GPH per side. Since fuel flow is the limiting factor for power output LOP, you can figure about 13.75 HP per each GPH of fuel for these lower compression turbocharged engines, which means I'm running about 125 HP per side, or maybe 63%. At that I get about 160 Kts TAS at 10,000 feet, with the TAS increasing a little as I go up. I run without Ox, so I usually stop at 12,000 feet.
I have had no problems LOP. Hottest cylinder in cruise is generally 370 deg or so. Occasionally the MP on the left engine runs away upside (only on the left - go figure). I usually run without altitude hold, just trimmed to level, and if the airplane starts to go up, I look at the MP immediately and so catch any transience before it goes very far or very long. The engines seem smoother LOP than ROP.
FWIW, I learned to fly in 1966 and instructed a fair amount during the next ten years. Nobody was more strident than I was about running over square or over lean (or probably any more ignorant, either). So the journey for me to accept these concepts was a painful one. But the basic knowledge of the effect of ROP/LOP on engine temps and internal cylinder pressures has been around since the advent of turbo compound round engines after WWII. Even if I didn't need to squeeze all the range I possibly could out of my miserable little fuel tanks, I don't think I would run a turbocharged engine any other way today.
I have the non-turbo TCM IO-360ES in my SR-20. It has run LOP exclusively for the last 1400 hours. It is an early SR-20 model with the very tight cowl - so in the beginning it was not unusual to see us busting through redline (380) right on takeoff passing 500 feet - IF WE WERE ROP with the boost pump on. What we ended up doing was adapting our procedures to essentially going LOP during the climbout - that is, doing the big pull when clear of obstacles. So our flows would essentially go from 19 GPH at takeoff to 10.7 GPH at sea level when transitioning to the cruise climb, and be leaned at a rate of .2 GPH per 1000 feet. This gave us MUCH lower CHTs during the climbout and cruise phase then keeping everything on the ROP side.
Oil analysis has been clean, nickel in the .3 ppm, chromium and other cylinder metallurgy has been below the trends Black Stone Labs has established and we fly on average 400 hours per year.
Keep in mind, the worst thing for any piece of technology whether a computer or 1930s engine is TEMPERATURE. The 460* we see for redline is for purposes of certification - its not a real number that means anything. You gotta keep things cool, and that means running brutally lean of peak or stupidly really rich of peak to the point where it is economically unfeasible. At 700 per Jug, LOP has not failed me. Its saved me probabally $25,000 in fuel costs and I got the oil analysis reports to prove it.
I have a 1979 Seneca II with intercoolers, a JPI 760 Twin, and Turbo Gami's. I have been routinely running lean of peak using APS's techniques for 3 years now. Since I have the original fixed waste gate turbos, setting the power is a little touchy and it is not a set and forget since power does change with airspeed changes.
The limiting factor for my engines is always TIT. My technique is to level off and accelerate to normal cruise airspeed, then pull the props back to 2400 RPM, adjusting the throttle to about 28-29 inches. I then do the "big pull" with the mixtures to make sure I am lean of peak. This usually occurs around 10 GPH. I then slowly enrich the mixtures until TIT is around 1590. Note that my MP will increase to about 30 inches during this time. This usually occurs around 10.5-11GPH. With this technique my CHT's never approach 380 which is the limit APS recommends, and I get around 165-170 knots true. After 3 years I have had no engine problems and just came out of annual with no engine work.
Once set, I normalize the engine monitor and this quickly identifies any deviations. I don't readjust every time I see any change because the TIT will fluctuate with airspeed. I try to find a setting where the TIT centers on 1590 and doesn't get above about 1630 (red line 1650).
When I need more speed I do run rich of peak, but always 100 degrees rich of peak. As mentioned in a previous post, 50 degrees rich of peak is the absolute worst place for the engine at high power settings since the temperatures and pressures are at their peak there.
Say what you will about APS, they have reams of data to prove there positions, or maybe I just drank their kool aide. As a former flight instructor I also never thought I would run lean of peak, but it clearly is better for the engine and for my pocketbook.
1. Takeoff is full rich, 34-38 inches of manifold pressure, full RPM.
2. Climbout is full rich, 31 inches, 2450 RPM.
3. Cruise, up to 10,000 feet - throttle MP back to 28 inches, RPM at 2300, and pull the mixture back to 10 gph, and then adjust for a EGT of 1550 degrees, lean of peak (about 75 degrees of peak.)
4. Cruise, over 10,000 feet - 27 inches and 2400 rpm, same EGT setting.
I have done this the last 600 hours, and I have never seen CHT's rise above 380 degrees on the hottest days. Borescopes and compressions have indicated no noticeable wear or adverse conditions in the last 600 hours either. The only problem I've encountered is that mixture and throttle settings become very sensitive and twitchy above 10,000 feet. Aside from that, economy has been great. I researched LOP operation soon after acquiring my Arrow as I was not enamored with the fuel consumption I saw initially.
As long as you keep the power at 65% or below (which I do), you really don't have anything to lose by running lean of peak. If one or two of your cylinders is running at peak EGT, then so what? Continental allows peak EGT operation at 65% power or less, and that's still better for your engine than running it at 25-50 degrees rich of peak. If you want to avoid cooking cylinders, either 1) run very rich, 2) run very lean, or 3) back off the cruise power.
When you are running as above what kind of TIT temps are you seeing
I think mine would be heading for 1600 under those settings
I also have the intercooler same as you do ?
maybe different in the fuel settings
Ian, I have a single point EGT/TIT monitor. Peak at 28 inches of manifold pressure in cruise is somewhere around 1610 - 1630 degrees. I usually just set my fuel flow so I'm in the range of 1550 degrees and fine tune it from there. You should be able to pull the mixture back and get whatever EGT/TIT you desire, under the same conditions. I can actually run my engine at around 1520 degrees before it starts to get rough.
Remember though that once you go lean of peak, manifold pressure and power management gets touchy, especially at high altitudes - at that point you are regulating power primarily with fuel, not with air.
Kareem Fahmi wrote
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Not to open a can of worms, but the data from the Advanced Pilot Seminar guys shows that 50 ROP is the *worst* place to run an engine. You either want to be 100 ROP or richer, or you want to be LOP.
50 ROP (EGT) is right where the internal cylinder pressures are at their highest. Same for CHT.
This is from Lycoming:
Lycoming recommends cruise operation at peak EGT or TIT, which is the point where the best economy range starts. For optimum service life, Lycoming suggests operating 50 degrees rich of peak EGT or TIT.
Lycoming does not recommend running LOP on their engines. They do state that you CAN run LOP but it is difficult to do correctly and can lead to engine damage. The report is only 4 pages long and makes for interesting reading. I am sure GAMI would refute this
Also Yes, I understand this thread was about the Continental Engines, However, I felt it was interesting to show Lycomings position on this subject. I had heard about the 50 degree ROP issue before and was running mine at least 100 ROP due to that, Now I use 50 ROP.
prothct Wrote:
>
> This is from Lycoming:
>
> Lycoming recommends cruise operation at peak EGT
> or TIT, which is the point where the best economy
> range starts. For optimum service life, Lycoming
> suggests operating 50 degrees rich of peak EGT or
> TIT.
>
I know that's what Lycoming says. The guys over at Advanced Pilot Seminars have some very convincing data to indicate that Lycoming is dead wrong, at least if you are operating above 65% power.
Below 65% power, you can run the mixture wherever you want without hurting anything. At 65% and above, according to the APS data, 50 ROP is the worst place to be because the internal cylinder pressures (ICPs, which we pilots cannot directly measure with a gauge in the cockpit) are at their highest.
I run my T-Arrow in the same way Sac Arrow describes, except I run 100 ROP at 65%. I plan to try LOP operations when I get some turboGAMIs installed.
