I’m still getting used to running LOP during cruise, and so far I’m loving the increased efficiency, lower CHT’s etc, and of course, fuel savings and range.
I’ve noticed a little peculiarity however that I was wondering if the group could shed some light on.
If I set cruise power (WOT/2400) and slowly lean the mixture, I typically get a fuel flow around 7.5gph running 50 LOP. When I’m closing in on his value I’ll lean the mixture .2 GPH at a time letting the temps stabilize each time until I get to 50LOP. The engine runs okay this way, but there is a very occasional stumble (maybe one in a 2 hour flight) that clears up if I push the mixture up. However EGT’s show that I truly am 50 LOP.
If instead I do a big pull to 7 GPH or so, and let the temps stabilize, then richen the mixture, find peak, then lean from that peak back to 50 LOP, I typically end up around 8.0 GPH. Again, showing 50 LOP, and the engine runs considerable smoother.
So…what gives? Shouldn’t peak EGT, and therefore 50 LOP be the same fuel flow regardless of which direction it’s approached from? I’m inclined to run the second way, since the engine runs smoother this way, but I’d like to ensure that I’m actually 50LOP using both methods, and not inadvertently ending up in the “red fin” of areas to avoid.
I’ve noticed a little peculiarity however that I was wondering if the group could shed some light on.
If I set cruise power (WOT/2400) and slowly lean the mixture, I typically get a fuel flow around 7.5gph running 50 LOP. When I’m closing in on his value I’ll lean the mixture .2 GPH at a time letting the temps stabilize each time until I get to 50LOP. The engine runs okay this way, but there is a very occasional stumble (maybe one in a 2 hour flight) that clears up if I push the mixture up. However EGT’s show that I truly am 50 LOP.
If instead I do a big pull to 7 GPH or so, and let the temps stabilize, then richen the mixture, find peak, then lean from that peak back to 50 LOP, I typically end up around 8.0 GPH. Again, showing 50 LOP, and the engine runs considerable smoother.
So…what gives? Shouldn’t peak EGT, and therefore 50 LOP be the same fuel flow regardless of which direction it’s approached from? I’m inclined to run the second way, since the engine runs smoother this way, but I’d like to ensure that I’m actually 50LOP using both methods, and not inadvertently ending up in the “red fin” of areas to avoid.