Toobuilder
Well Known Member
Much has been written on this forum concerning the pros and cons of electronic ignition and more specifically, the level of advanced timing they offer. Plenty of testimony that Lycomings "like" more timing than offered by the fixed magneto, and plenty of testimony that the factory knows best. There has also been dyno testing between the two, but the results have been less than convincing for either side. The current crop of electronic ignitions have fairly limited to zero adjustability and the curve seems somewhat mysterious. In my mind, what is needed is a completely adjustable ignition which you can tweak on the fly. Being able to set power, then move the timing around to see where the engine is happiest should put the issue to bed, shouldn't it?
Well, I have just installed an electronic ignition with that capability and I have done some preliminary testing. First off, the ignition is the new CPI product from Ross Farnham and it offers essentially an infinitely adjustable advance curve for RPM as well as a second curve based on MP. This system replaces one of the Slicks on my Rocket. On the first flight I set up a conservative advance essentially duplicating the 26 degree timing of the magneto and was able to replicate my typical cruise performance. Without touching anything but the ignition advance I was able to pick up a few knots of speed. The second flight was a data gathering flight to see if it was a fluke. The performance repeated.
Attached is a table transcribing the hand written notes from that flight. The method of testing was to get the airplane set up at cruise altitude, on autopilot and with a typical power setting (in this case, slightly LOP). I started at 26 degrees advance (duplicating the magneto timing) as my "baseline". Once stable, I would punch in some advance, let the ship stabilize, and then write down the results. Each change would stabilize in about 30 seconds, so I was able to cycle through the whole test in one 20 minute flight.
This is still very preliminary and some of the individual measurements dont track exactly as one would expect, but the overall trend is obvious. I thought it interesting enough to share. There will be much more testing shortly.
Well, I have just installed an electronic ignition with that capability and I have done some preliminary testing. First off, the ignition is the new CPI product from Ross Farnham and it offers essentially an infinitely adjustable advance curve for RPM as well as a second curve based on MP. This system replaces one of the Slicks on my Rocket. On the first flight I set up a conservative advance essentially duplicating the 26 degree timing of the magneto and was able to replicate my typical cruise performance. Without touching anything but the ignition advance I was able to pick up a few knots of speed. The second flight was a data gathering flight to see if it was a fluke. The performance repeated.
Attached is a table transcribing the hand written notes from that flight. The method of testing was to get the airplane set up at cruise altitude, on autopilot and with a typical power setting (in this case, slightly LOP). I started at 26 degrees advance (duplicating the magneto timing) as my "baseline". Once stable, I would punch in some advance, let the ship stabilize, and then write down the results. Each change would stabilize in about 30 seconds, so I was able to cycle through the whole test in one 20 minute flight.
This is still very preliminary and some of the individual measurements dont track exactly as one would expect, but the overall trend is obvious. I thought it interesting enough to share. There will be much more testing shortly.
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