For a 2 stroke it is very efficient (we have 2-stroke engines over 2.5 HP running absolutely reliable in exact the same configuration) but for a fourstroke it is minimal.
In this case, Vario recommended to give the engine a very thorough break in, reduce oil content to minimum and keep the engine as close as possible to 11000 RPM. But this version was discontinued already 10 years ago and was only around for maybe 2 or 3 years.
In the basic trainer it is working OK, because the engine is not loaded so much continuous (required power is lower in hoover/cruise, compared to my Bell 47G). The engine will handle a longer climb-out as the engine more or less works as its own heatsink; you end the climb, before the engine gets too hot, or you will be too high anyway. Not so in my over 1 kilo heavier Bell 47G.... It runs hotter in hoover, and climbs slower so you have to maintain climb longer to get altitude....
This helicopter has always been just able to hoover and maybe climb with a few feet per second. Heat has always been a bit of a problem, usually I left it home when it was over 20 degrees outside.
But it is what it is, and I am just trying to optimize it. The running behaviour has at least improved considerably, and during that phase that is is still heating up, power seems to have improved.
Needles seem a lot less critical.
Now I am trying to "unleash all that power"
by keeping the engine cooler, as there is definitely a fair amount of power extra at lower engine temperatures. That was never there in such amounts: when the engine was still glow, the difference between hot and cold was a lot less and the mixture range over which the engine ran good was a lot smaller.
But it is just.... I have had the fortune to see Bell 47 G's with the open pipes on that 6 cylinder Lycoming, and the sound of the OS , the flight performance of the helicopter is so very realistic, I can't just decommision it....