  According to classical Boltzmannian thermodynamics, the efficiency of a
cyclic machine is strictly lower than one. Such a result is a straightforward
consequence of the second principle of thermodynamics. Recent advances in the
study of the thermodynamics of long-range interacting system report however on
a rather intricate zoology of peculiar behaviors, which are occasionally in
contrast with customarily accepted scenarios, dueling with intuition and common
sense. In this paper, a thermodynamical cycle is assembled for an ideal device
working with non-Boltzmaniann long-range fluid and operating in contact with
two thermal reservoirs. The system is analytically shown to violate the second
principle of thermodynamics, a phenomenon that ultimately relates to the
existence of regions with negative kinetic specific heat, in the canonical
ensemble for the system under scrutiny. We argue that the validity of the
second principle of thermodynamics can be possibly restored, by revisiting the
definition of canonical ensemble, as well as the Fourier law of heat transport,
and consequently relaxing the constraint on the maximal efficiency as imposed
by the Carnot theorem.
