An internal combustion engine comprising: an intake cylinder to accommodate intake and pre-compression of an oxidizing agent; a combustion cylinder to accommodate a further compression of the oxidizing agent, an injection and ignition of fuel, and a partial expansion of combustion gases produced by the ignition of fuel; and an exhaust cylinder to accommodate a further expansion of the combustion gases and subsequent exhausting of the further expanded combustion gases; a reciprocating piston (126, 128, 130) inside each of the intake, combustion and exhaust cylinders; a crankshaft coupled to the reciprocating pistons; a first transfer passage to facilitate flow of the pre-compressed oxidizing agent from the intake cylinder to the combustion cylinder; a first transfer valve to regulate flow of fluid through the first transfer passage; a second transfer passage to facilitate flow of the partially-expanded combustion gases from the combustion cylinder to the exhaust cylinder; and a second transfer valve to regulate flow of fluid through the second transfer passage, wherein, during operation, the reciprocating piston inside the combustion cylinder is approximately at the center of its expansion stroke and is moving from top dead center to bottom dead center, when the second transfer valve between the combustion cylinder and the exhaust cylinder has just opened, and wherein the second transfer valve closes when the reciprocating piston inside the combustion cylinder reaches close to bottom dead center, and wherein just as the reciprocating piston inside the combustion cylinder reverses direction, the first transfer valve opens and the reciprocating piston inside the intake cylinder pushes a fresh charge of air in, wherein the first transfer valve is located at a top of the combustion cylinder and at an end of the first transfer passage, wherein the second transfer valve is located at the top of the combustion cylinder and at a beginning of the second transfer passage, and wherein the exhaust cylinder has a larger bore than the intake cylinder and the combustion cylinder has a smaller bore than the exhaust cylinder and the intake cylinder. an intake cylinder to accommodate intake and pre-compression of an oxidizing agent; a combustion cylinder to accommodate a further compression of the oxidizing agent, an injection and ignition of fuel, and a partial expansion of combustion gases produced by the ignition of fuel; and an exhaust cylinder to accommodate a further expansion of the combustion gases and subsequent exhausting of the further expanded combustion gases; a reciprocating piston (126, 128, 130) inside each of the intake, combustion and exhaust cylinders; a crankshaft coupled to the reciprocating pistons; a first transfer passage to facilitate flow of the pre-compressed oxidizing agent from the intake cylinder to the combustion cylinder; a first transfer valve to regulate flow of fluid through the first transfer passage; a second transfer passage to facilitate flow of the partially-expanded combustion gases from the combustion cylinder to the exhaust cylinder; and a second transfer valve to regulate flow of fluid through the second transfer passage, wherein, during operation, the reciprocating piston inside the combustion cylinder is approximately at the center of its expansion stroke and is moving from top dead center to bottom dead center, when the second transfer valve between the combustion cylinder and the exhaust cylinder has just opened, and wherein the second transfer valve closes when the reciprocating piston inside the combustion cylinder reaches close to bottom dead center, and wherein just as the reciprocating piston inside the combustion cylinder reverses direction, the first transfer valve opens and the reciprocating piston inside the intake cylinder pushes a fresh charge of air in, wherein the first transfer valve is located at a top of the combustion cylinder and at an end of the first transfer passage, wherein the second transfer valve is located at the top of the combustion cylinder and at a beginning of the second transfer passage, and wherein the exhaust cylinder has a larger bore than the intake cylinder and the combustion cylinder has a smaller bore than the exhaust cylinder and the intake cylinder.