G
Geoff
It seems like the "aversion to leaning engines" thread has spawned a new LOP debate in a few messages -- hence I'm starting a new thread to provide a very simple data point.
My engine is an IO-360, vertical induction, Precision Silver Hawk injected, dual P-mag sparked piece of awesome machinery built by Mattituck. This engine was very well balanced between the cylinders from day one, so I never needed to mess with different injector restrictor sizes. All cylinders peak within 0.0 to 0.4 GPH of each other, depending on the day, and the engine runs smooth when leaned almost right up until it quits. That's good enough for me.
Anyway... I usually use the "lean find" feature of the engine monitor. Basically I engage that mode after reaching cruise and start leaning. For LOP operations, it detects the LAST cylinder to peak and then tells me how far LOP it is once it goes over peak. I usually cruise 20-80 degrees LOP on the richest cylinder, depending on the conditions. Works good, lasts long time.
I got to thinking that before all the fancy instrumentation, I used to fly airplanes by leaning until rough and then enriching slightly. For fuel injection, that technique is modified to leaning until a power loss is detected and then enriching slightly. This also works good, lasts long time. Interestingly, this technique is almost the same thing as Deakin's "big pull" technique that he describes in numerous articles.
So today I pretended I didn't have an engine monitor. After reaching cruise, I gave the red knob a big yank until I detected a power loss. Then I pushed it in slightly. Guess where I ended up? About 50 degrees LOP on the richest cylinder -- right in the middle of my normal cruising range. Well how about that!
My conclusion? Some people make a much bigger deal about this than is really necessary. These engines have been running a lot longer than we've had fancy engine monitors. I'd be willing to bet that the "standard" technique for leaning a fuel-injected engine without any instrumentation (lean until power loss is detected, then enrichen) results in operating LOP at least some of the time -- we just didn't know it.
And if all of this is too much to digest, Deakin's most basic rules are very easy to remember. At a reduced power setting and/or at any power setting higher than altitude of about 8000-ish feet, you're not going to blow up the engine no matter what you do with the mixture. At high power settings at lower altitudes, use enough fuel flow to keep the CHTs from getting out of control and you're not going to do any damage either.
Sometimes fancy electronics predispose us to overthink things... Go try some of this stuff. Experiment. You just might save some fuel in the process...
My engine is an IO-360, vertical induction, Precision Silver Hawk injected, dual P-mag sparked piece of awesome machinery built by Mattituck. This engine was very well balanced between the cylinders from day one, so I never needed to mess with different injector restrictor sizes. All cylinders peak within 0.0 to 0.4 GPH of each other, depending on the day, and the engine runs smooth when leaned almost right up until it quits. That's good enough for me.
Anyway... I usually use the "lean find" feature of the engine monitor. Basically I engage that mode after reaching cruise and start leaning. For LOP operations, it detects the LAST cylinder to peak and then tells me how far LOP it is once it goes over peak. I usually cruise 20-80 degrees LOP on the richest cylinder, depending on the conditions. Works good, lasts long time.
I got to thinking that before all the fancy instrumentation, I used to fly airplanes by leaning until rough and then enriching slightly. For fuel injection, that technique is modified to leaning until a power loss is detected and then enriching slightly. This also works good, lasts long time. Interestingly, this technique is almost the same thing as Deakin's "big pull" technique that he describes in numerous articles.
So today I pretended I didn't have an engine monitor. After reaching cruise, I gave the red knob a big yank until I detected a power loss. Then I pushed it in slightly. Guess where I ended up? About 50 degrees LOP on the richest cylinder -- right in the middle of my normal cruising range. Well how about that!
My conclusion? Some people make a much bigger deal about this than is really necessary. These engines have been running a lot longer than we've had fancy engine monitors. I'd be willing to bet that the "standard" technique for leaning a fuel-injected engine without any instrumentation (lean until power loss is detected, then enrichen) results in operating LOP at least some of the time -- we just didn't know it.
And if all of this is too much to digest, Deakin's most basic rules are very easy to remember. At a reduced power setting and/or at any power setting higher than altitude of about 8000-ish feet, you're not going to blow up the engine no matter what you do with the mixture. At high power settings at lower altitudes, use enough fuel flow to keep the CHTs from getting out of control and you're not going to do any damage either.
Sometimes fancy electronics predispose us to overthink things... Go try some of this stuff. Experiment. You just might save some fuel in the process...
