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Final Approach
I've been interested for a while in finding out if I can run LOP with my current (non-GAMI) injectors so yesterday I printed out the GAMI data form, took my Cardinal up to 7800 MSL (pressure altitude 7500), chose a 65% (by the POH) power setting, and tried to run the longhand form of the lean test.
I failed. The main problem was that I couldn't figure out how to get my EDM-700 to display the cylinder I wanted it to display in Lean Find mode. It turns out it can't do that, in LF mode it only displays the warmest cylinder. In Manual Mode the digital EGT display only has 10F resolution, which isn't good enough for the test. So instead I tried reverting to the shorthand form of the test after finding the first cylinder to peak (#3). The problem is that #4 peaked next, at a lower temp than #3 so it never displayed in LF mode. In fact I wasn't able to record its peak temp as the display just flashed "PEAK EGT" while switching to #4, without telling me the actual EGT value. Then #2 started to climb up to about 1470 -- and went up and down a few times as I continued to lean very slowly. I then switched to #1 in manual mode and found that it was already LOP -- LF mode had never informed me of that fact. So basically LF mode is useless for the lean test.
Later at night I learned (by RTFing) that it's possible to change the EGT resolution. What I'm wondering now is whether I should just do it again (quite time consuming, I was up there fiddling around for about 45 minutes) or whether I already have enough information to know that I can't run LOP. Here's the relevant data on each cylinder:
cylinder.......PEAK EGT(F)..........FF(gph)
#3.................1450.................8.7, 8.5 (did this twice)
#4.................unk...................8.0
#1...............~1440.................unk, but <8.5
#2.................1470-1480.........7.8
So it seems my total FF spread is 0.7-0.9 gph which is well above the GAMI ideal of 0.5. Also, it seems I really can't run #2 LOP at all as the engine starts running noticeably rough in that regime.
However I never saw alarmingly high CHTs, in fact during the test they were always lower than they were during climbout (315 or less). LOP they were back down in the high 200s -- and even at peak EGT, #2's CHT was cooler than #3 at peak EGT (302). I typically only see CHTs above 350 during climbout in summer heat. According to Mike Busch, CHT is the best proxy for ICP... not sure how to apply that concept to my (apparently) unusually cool-running engine.
I failed. The main problem was that I couldn't figure out how to get my EDM-700 to display the cylinder I wanted it to display in Lean Find mode. It turns out it can't do that, in LF mode it only displays the warmest cylinder. In Manual Mode the digital EGT display only has 10F resolution, which isn't good enough for the test. So instead I tried reverting to the shorthand form of the test after finding the first cylinder to peak (#3). The problem is that #4 peaked next, at a lower temp than #3 so it never displayed in LF mode. In fact I wasn't able to record its peak temp as the display just flashed "PEAK EGT" while switching to #4, without telling me the actual EGT value. Then #2 started to climb up to about 1470 -- and went up and down a few times as I continued to lean very slowly. I then switched to #1 in manual mode and found that it was already LOP -- LF mode had never informed me of that fact. So basically LF mode is useless for the lean test.
Later at night I learned (by RTFing) that it's possible to change the EGT resolution. What I'm wondering now is whether I should just do it again (quite time consuming, I was up there fiddling around for about 45 minutes) or whether I already have enough information to know that I can't run LOP. Here's the relevant data on each cylinder:
cylinder.......PEAK EGT(F)..........FF(gph)
#3.................1450.................8.7, 8.5 (did this twice)
#4.................unk...................8.0
#1...............~1440.................unk, but <8.5
#2.................1470-1480.........7.8
So it seems my total FF spread is 0.7-0.9 gph which is well above the GAMI ideal of 0.5. Also, it seems I really can't run #2 LOP at all as the engine starts running noticeably rough in that regime.
However I never saw alarmingly high CHTs, in fact during the test they were always lower than they were during climbout (315 or less). LOP they were back down in the high 200s -- and even at peak EGT, #2's CHT was cooler than #3 at peak EGT (302). I typically only see CHTs above 350 during climbout in summer heat. According to Mike Busch, CHT is the best proxy for ICP... not sure how to apply that concept to my (apparently) unusually cool-running engine.