Generally speaking on combustion (piston) engines the max torque (and efficiency) is at revs between 2/3 and 3/4, sometime 4/5 of power peak revs, and in "stati

Generally speaking on combustion (piston) engines the max torque (and efficiency) is at revs between 2/3 and 3/4, sometime 4/5 of power peak revs, and in "static" applications (i.e. when you don't have an accelerator that you use continuously) such as aviation but also power generators, hydraulic loaders and excavators, etc. they normally are operated (continuously) at those levels range (around max torque).