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Maybe, I will be up there this weekend so if I can help give me a call. We can also get a few of the other 10 owners on the field to give us their thoughts. If your going to the chapter event Saturday night I'm sure we can find a few opinions.
If the engine was running lean the temps would be high so I am pretty sure that's not it. Just different from my engine. I am also under 100 hours and don't lean as aggressively as others might. Pat |
David,
I enjoyed talking with you yesterday on face time and although Johns issue may be different the feedback you provided was appreciated. I will check out the training event in Ada Ok in March and see if I can fly my 10 up there. Pat Quote:
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Gentleman,
I am writing this post to correct a few myths and misunderstandings about running in engines, fuel flow and EI's. First of all, the little bit of advance that makes LOP ops better is in the order of a couple of degrees, however this is only good when LOP, for you ROP guys it is actually less of a good thing especially when running around 50dF ROP. Fuel flow will vary depending on altitude, but for typical cruise altitudes of around 7500-9500' when running appropriately LOP, will be 11.0-10.5GPH. This is regardless of the type of ignition you are running. As for breaking in the engine, you want to do this with low peak pressures and high mean effective pressures. This means the break in happens over a wider pass of the piston/cylinder, without the high peak. Given that we can generate the same torque and BMEP by varying the peak pressure and theta PP, which combination is going to give us better mean effective pressures and lowest peak pressures? Which method is going to give us lower CHT's? Which method is going to give us cleaner rings and cylinders? If the answer to the above was Rich of Peak run in, I would thoroughly endorse it. However the answer is actually the opposite. So you are far better to run in your engine LOP. Sure at takeoff full rich, but at 1500-2000' a big mixture pull and run in at high HP LOP. The choices are 75% or more power, either full rich or 80dF LOP. Take your pick. Of course you need to have good F/A ratios in order to do this, and there is no problem doing this on your second flight to determine if you have a good gami spread. If you do not get it fixed and continue flying the phase 1. This notion that Quote:
I frequently remined myself during discussions such as these that it's often true that no amount of data can replace the comforts of a closely held superstition. Below is a photo I post regularly, this would be a perfect break in setup, so long as the air was smooth, or adjust accordingly by going a fraction higher. ![]() |
My new factory engine with unbalanced injectors runs fine at 30-40F LOP. I doubt any new factory engine will run smooth at 80F LOP for break-in as you mentioned above.
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Confucius say: Do not tell man something impossible when he already doing it! :D
Wayne your doubts are well founded?.only some of the time. In my case with a factory Lycoming you would be forgiven for making that satement, it was a shocker, so bad we could not even do a GAMI lean test and had to do some guesses to start with just to get anything near peak EGT. Yet a year or so later while flight testing another RV10 with a stock factory IO540?..0.2GPH spread and would run happily 80dF LOP at 2000'. I was stunned! An RV7 owner with an Aerosport Power engine down here gets 0.0 spread, it is that good. I suspect that AP did a great job on the dyne before shipping, or they just got lucky. Wayne, your new engine runs fine 30-40dF LOP, but at what MP and RPM? This varies with power(Altitude). If you can do that at 10'000 feet that suggests a good spread, and chances are at 1000' as shown above you can also run down to 100dF LOP. 30-40dF LOP at 10,000' is vastly different to 1,000'. |
16,500', DA= 18,370', 16.1" mp, 2430 rpm, 7.9 gph, IAS= 105 kts, TAS= 136 kts, 16 nmpg with a 14 kt headwind, +6 degrees pitch, 225F cowl exit temp(hottest ever), CHT= 307-331F, OAT= 32F, gross weight, near aft cg limit. That is the highest that we have been and it ran smooth 30-40 LOP. Mine does not want to run smooth beyond 40-50F down low. We lose a lot of speed running LOP, so can't imagine wanting to run any leaner. We are very happy with the engine and plane.
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Wayne, I see your problems.
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you had a DA of 18000' and at 40LOP it was almost stopped! 10dF LOP and no more. In fact 75dF ROP up there would be better. Quote:
Tell me this, what is your procedure for leaning and setting the LOP cruise setting, and I might be able to help you out. Quote:
How many hours on the engine? What plugs do you use? How long since they were gapped? How many hours on them? Can you send me a EMS data file? |
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You're asking the pilot of a brand new, unfamiliar airplane to make a rapid mixture pull to a point close to cutoff, probably with untuned injectors, while close to the ground. Failure to do the Big Pull in a rapid manner (i.e. slowly easing up to peak from the rich side) risks engine damage. Isn't that asking a bit much? Quote:
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Dan,
Take a risk and show you the data. Sure when you sign a NDA which covers a whole load of things, and you get involved with a certification project that clearly shows everything you could want to know and more, why not! Simpler option would be pony up with the cash and do the next course in Ada OK and George will show you real live data of the sort you want to see. I have seen plenty of it and quite a lot lately. But that is not for public consumption. Having said that I can pull some info from the course which are straight from the dyno hard data, or even some of John Deakins old articles. But let me answer a question or two for you. You asked; Quote:
David Brown said.. Quote:
The first Data block I have noted is at peak or just lean of peak, in an attempt to keep the HP the same rather than the reduced power and obviously even lower PSI's. The second is full rich. 1. MP=31" RPM=2400 BMEP 133.9 BHP=219 ICP's ranged 600-620PSI 2. MP=31" RPM=2395 BMEP 136.6 BHP=223 ICP's ranged 750-780PSI Quote:
By the way the Lycoming data comes from a source that is far behind in my opinion the FAA test centre or the GAMI one, they do not use the currently accepted detonation algorithms and that graph you refer to only shows frequency (Hz) of events. It does nothing for intensity and this is the key point. George has demonstrated this on his test stand to the FAA, and it is like asking yourself, in a hail storm which deposits hail on your car, or better still if you are a car salesman with a yard full of cars. And it deposits 1000 hail stones weighing 0.2grams each on your yard. The other choice is 10 hail stones at 20grams each. Which one is going to give your insurance company the shivers? So intensity matters. Frequency not so much. Your statement above is somewhat accurate in that detonation occurs in the renege from 50ROP to 50LOP, but it is no more accurate than a statement like 200ROP to 100LOP. A truer statement might be something like 75ROP and 10ROP. So back to the claim that doing a BMP while running in your engine will be running the engine where "there is a very good chance it is going to detonate in the mixture region between 50 ROP and 50 LOP", and how on earth in a few seconds you are going to heat up the oil, heat up the CHT's create 30"MP and 2400 long enough for even one detonation event to take place? I fail to see how that is even remotely possible. For the audience out there, running a conforming engine on conforming 100LL and doing a BMP, even with CHT's over 400dF we have never seen detonation happen and even with purposely driven high oil, air, CHT and the ability to run 33" or more we have not seen this with a BMP. OK next one, Quote:
B probably with untuned injectors Probably so, the only way they would have been tuned is if they were done by Aerosport or Riverina or someone on their engine test cell, but it is possible to have decent enough F/A ratio's out of the box sometimes. Maybe this would be a good time to sort that out? C while close to the ground For the purposes of doing aero's or stalls on your second flight 1500-2000' I would surely call that close to the ground. But to manipulate the mixture knob? Surely you are kidding me. If you or they are that scared they may not have fastened it right to the FCU, do it 2000' above the field. D Failure to do the Big Pull in a rapid manner (i.e. slowly easing up to peak from the rich side) risks engine damage. I think if you had done any of this even doing it slowly on either the FAA's or GAMI's test cell you would not be so scared and willing to believe the BS Lycoming have printed. Even doing it slowly over 30 seconds is not going to hurt anything. The problem is by doing it slowly is not anything to do with engine harm, it is that you will not feel the deceleration at all when going safely into LOP territory. So the BMP is not any use if it is a SMP. E Isn't that asking a bit much? No not at all. I suggest you email the editor of the AOPA's Australian magazine http://www.aopa.com.au/magazine and ask her about her first BMP done overwater at 1500' and see how she responds. So all the smarter tougher and more macho test pilots should be able to cope. Take a Risk Dan??go see the data for yourself. http://www.advancedpilot.com/store.html If you don't learn anything at all, Deakin will write you a cheque. |
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