Question about climbing "full rich". Would it not make sense to maintain sea-level EGT's through the climb, rather than truly full rich all the way up to 17K? As you climb higher, 'full rich' is a whole lot richer than the mixture you
had during takeoff. This is something I learned through John Deakin's Pelican Perch articles a few years back when I first got the Lancair. I usually 're-lean' every
1000ft or so during my climbs to maintain around 1320 EGT.
LNC2 N360JH
Keith,
Leaning to maintain a power setting as you climb will work as you note. The result is that the engine continues to produce
as much heat at altitude as it does at sea level, while the air thins and doesn’t carry the heat away as well. This usually results in higher CHTs and oil temps. The reason for using “full rich” during climbs…or any high power operation for that matter…is
to deliver extra fuel…for cooling…to the cylinders. Not the most efficient use of expensive fuel, but it has other advantages, principally that of keeping the engine temps within limits at lower airspeeds while still delivering sufficient power to climb. The
throttle control on our Continental and Lycoming engines (and probably others?) is designed to also deliver extra fuel at wide open throttle (WOT)--to aid cooling. So climbing at WOT and full rich “wastes” fuel, but really helps the engine deliver its rated
service life.
As many have said in these pages, it’s all about keeping the engine temps within specified limits. As long as you can
monitor and control CHTs and oil temps on our air-cooled engines, you should be OK to lean during climb, but if the temps start approaching the specified limits, you need to change things. This can include increasing airspeed/cooling air flow, reducing power,
or adding more fuel--via the throttle and/or the mixture control.
Hope this helps…
Bob