If this is your first visit, be sure to check out the FAQ by clicking the link above. You may have to register before you can post: click the register link above to proceed. To start viewing messages, select the forum that you want to visit from the selection below. |
|
|
Thread Tools | Display Modes |
#31
|
|||
|
|||
Howard,
After a couple of minutes the EGT's were all within 25 degrees of each other. Just to make something clear about a common misunderstanding he The goal is NOT to have the EGTs equal. The goal is to have the EGTs in equal distance from their respective peak. The absolute EGT value doesn't matter. -- Thomas Borchert (EDDH) |
#32
|
|||
|
|||
Juan,
That's not what Continental says about their engine, and not what TBO Advisor recommends. Not sure what you mean. What part of the statement you quoted Continental doesn't say? -- Thomas Borchert (EDDH) |
#33
|
|||
|
|||
Frank Stutzman wrote:
3) If I can't get smooth LOP operations with the above, I'll play a bit with carb heat (which is actually alternate air on my plane). Causing the induction air to be a few degrees warmer will often help get the vaporization (and hence good distribution) needed. How does improving vaporization improve distribution? |
#34
|
|||
|
|||
One of the things I found with my O-360 and C/S prop is that at
altitudes where the MP falls off, generally to 22" - 23", I pull the throttle back to see a slight decrease in the MP. Then I lean. I find I get better fuel burn results and very near the Lycoming manual for this engine. Leaving the throttle in full at high altitudes, tends to burn more fuel and I am not sure I am getting anything out of it. Comments? Regards, Ross C-172F 180HP KSWI Frank Stutzman wrote: Doug wrote: I think the main thing is to lean enough to get proper burn, but don't lean so much as to burn things up. I have some friends with probes on all cylinders and carbureted engines who have tried to run lean of peak and they have mostly given up. Just doesn't work on carbureted engines. If you said "most" carbed engines, I probably wouldn't quibble. However, it does work on some. It certainly works on my Continental E-225 with a Bendix PS-5C carb. Its harder to do, but can be done and does work. Here is what I had to do: 1) overhauled my carb and had it flow tested to make sure its doing its job. 2) Pull off the throttle back a bit less than one inch. This put the carb out of the enrichment mode that it is with full throttle. I think it may also put a bit of turbulence into the airflow that helps the fuel vaporization. 3) If I can't get smooth LOP operations with the above, I'll play a bit with carb heat (which is actually alternate air on my plane). Causing the induction air to be a few degrees warmer will often help get the vaporization (and hence good distribution) needed. I believe I've heard the GAMI folks say that getting good distribution is easiest on the large Continentals. Something to do with the way the stock induction is done. -- Frank Stutzman Bonanza N494B "Hula Girl" Hood River, OR |
#35
|
|||
|
|||
I should mention that I only have a single EGT probe on my engine. I
keep wondering if I should get an analyzer. So much I could buy... Regards, Ross C-172F 180HP KSWI Ross Richardson wrote: One of the things I found with my O-360 and C/S prop is that at altitudes where the MP falls off, generally to 22" - 23", I pull the throttle back to see a slight decrease in the MP. Then I lean. I find I get better fuel burn results and very near the Lycoming manual for this engine. Leaving the throttle in full at high altitudes, tends to burn more fuel and I am not sure I am getting anything out of it. Comments? Regards, Ross C-172F 180HP KSWI Frank Stutzman wrote: Doug wrote: I think the main thing is to lean enough to get proper burn, but don't lean so much as to burn things up. I have some friends with probes on all cylinders and carbureted engines who have tried to run lean of peak and they have mostly given up. Just doesn't work on carbureted engines. If you said "most" carbed engines, I probably wouldn't quibble. However, it does work on some. It certainly works on my Continental E-225 with a Bendix PS-5C carb. Its harder to do, but can be done and does work. Here is what I had to do: 1) overhauled my carb and had it flow tested to make sure its doing its job. 2) Pull off the throttle back a bit less than one inch. This put the carb out of the enrichment mode that it is with full throttle. I think it may also put a bit of turbulence into the airflow that helps the fuel vaporization. 3) If I can't get smooth LOP operations with the above, I'll play a bit with carb heat (which is actually alternate air on my plane). Causing the induction air to be a few degrees warmer will often help get the vaporization (and hence good distribution) needed. I believe I've heard the GAMI folks say that getting good distribution is easiest on the large Continentals. Something to do with the way the stock induction is done. -- Frank Stutzman Bonanza N494B "Hula Girl" Hood River, OR |
#36
|
|||
|
|||
"Ross Richardson" wrote in message ... I should mention that I only have a single EGT probe on my engine. I keep wondering if I should get an analyzer. So much I could buy... Regards, Ross C-172F 180HP KSWI More than anything else I have added to the aircraft the cost of installation and maintence of our Engine Analyzer was many times higher than the the actual cost of the unit. Seems to be a high maintence item. Howard |
#37
|
|||
|
|||
A couple of observations. If you are running rich of peak, you want ALL
they cylinders to be rich of peak and you use the leanest, highest temp cylinder as your guide. If you are running lean of peak, you want all the cylinders to be lean of peak, and you use the RICHEST, highest temp cylinder as your guide. One can see why it is good to have all they cylinders close to each other. This is what the Gami's do. As for carb heat. If you put on the carb heat you introduce hot air, which is less dense. You have just richened the mixture. As for throttle pull back. If you lean to roughness, then pull back the throttle, you have just richened the mixture. There is no magic. You can safely operate at high power setting rich of peak or lean of peak. To operate lean of peak you need (or want) EGT/CHT monitoring of all cylinders, fuel injection, Gamis and fuel flow monitoring to REALLY do it right. You MIGHT be able to operate lean of peak successfully with a carbureted engine, but most can't because of uneven air and fuel distribution. If you operate at about 50% power you can run as lean as you want because you won't be generating enough heat to do any damage. 65% power takes 50 degrees rich (or lean), 75% takes 100 degrees rich (or lean), 85% 150 degrees rich (or lean) etc. |
#38
|
|||
|
|||
"Thomas Borchert" wrote in message ... Doug, Running rich of peak aviods the peak settings that can overheat things and do damage. Not at all true. In fact, completely false. Sorry. Come on, Thomas. What in the world makes you think that the effects of heat due to leaning to peak EGT at high power settings are NOT going to create problems for the engine? This is common knowledge -- the closer your EGT gets to 1600 degF for extended periods, the higher the chances your engine will not reach or exceed TBO. Running at peak EGT at high power settings for extended periods -will- have a negative effect on your engine. That's why none of the manufacturers recommend doing this. It is false economy to try and run lean AT HIGH POWER SETTINGS and possibly damage your engine. lean? How lean? This statement is not true. No, it isn't. It's manufacturer recommendation. |
#39
|
|||
|
|||
"Thomas Borchert" wrote in message ... Juan, That's not what Continental says about their engine, and not what TBO Advisor recommends. Not sure what you mean. What part of the statement you quoted Continental doesn't say? Original message: At power settings above 65% you need to be concerned about running too lean, thus too hot. Your reply: Uhm, no, not at all. This is wrong. You DO have to be concerned about running too lean, which is why Continental does not recommend leaning for extended periods of time at high power settings (above 65%). |
#40
|
|||
|
|||
"Thomas Borchert" wrote in message ... Uhm, no, not at all. He'd have to be concerned to run not lean enough, actually, since the temps decrease again when running leaner and leaner. ....and the effects of increased oxidative attack on the exhaust negates the so-called advantage of low temps. In addition, TBO advisor adds that "very little cooling effect is coming from the fuel itself, so CHT does not respond in quite the same way you'd expect." Running lean of peak also results in reduced performance, rough engine operation in many cases and shortened TBO due to the above-mentioned oxidative attack of exhaust and combustion chamber components. Running lean of peak also has another side effect, increase in oil acidity, which causes oxidation in engine internal components (same thing happens if you don't operate the engine often enough to burn off any condensation in the oil). At lean of peak, exhaust gases are rich in oxides of nitrogen, which mix with moisture to create nitric acid, which happens to be extremely corrosive. In addition, TBO Advisor says there is direct evidence documenting a relationship between ntric acid and camshaft wear. Because of this, they recommend that if you're going to operate your engine at best economy mix, lean of peak, then change your oil every 25 to 50 hours (preferably closer to 25). This method is specifically not recommended for TSIO-360 series, O-470 and IO-470 series and several other series and models of engines. |
Thread Tools | |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
Parachute fails to save SR-22 | Capt.Doug | Piloting | 72 | February 10th 05 05:14 AM |
Leaning for taxi | Jim Rosinski | Piloting | 28 | September 12th 04 03:53 AM |
Procedure Turn | Bravo8500 | Instrument Flight Rules | 65 | April 22nd 04 03:27 AM |
Unusual Procedure at DFW | Toks Desalu | Piloting | 9 | December 17th 03 05:27 PM |
O-320 leaning | Roger Long | Piloting | 5 | November 8th 03 11:40 PM |