Abstract: An external combustion engine comprising a drive shaft, a first cylinder kinematically connected to the drive shaft, a second cylinder kinematically connected to the drive shaft, and a thermodynamic circuit fluidly connected to both the cylinders, and having at least an expansion chamber and a compression chamber for a heat-carrying fluid, in order to determine the cyclic movement of the first cylinder and the second cylinder. The first cylinder is mounted on a first support frame and the second cylinder is mounted on a second support frame, distinct from and constrained in a mobile manner to the first support frame. Movement means are mechanically connected to the first support frame and/or the second support frame, in order to determine the desired relative movement of the first support frame and the second support frame and to vary the reciprocal kinematic connection phasing of the two cylinders with respect to the drive shaft.