  In the context of dilaton coupled Einstein gravity with a negative
cosmological constant and a Born-Infeld field, we study heat engines where
charged black hole is the working substance. Using the existence of a notion of
thermodynamic mass and volume (which depend on the dilaton coupling), the
mechanical work takes place via the pdV terms present in the first law of
extended gravitational thermodynamics. Efficiency is analyzed as a function of
dilaton and Born-Infeld couplings, and results are compared with analogous
computations in the related conformal solutions in the Brans-Dicke Born-Infeld
theory and black holes in Anti de Sitter space-time.
