Engine system using alcohol Rankine heat recovery where the engine heat converts alcohol into hydrogen-rich gas which is then introduced into the engine cylinders. The engine system includes a source of liquid alcohol along with an internal combustion engine generating a high-temperature exhaust. Structure is provided for introducing a first portion of the liquid alcohol into the engine and a series of heat exchangers forming a Rankine heat recovery cycle is provided to extract heat from the exhaust and transferring the heat to a second portion of the liquid alcohol, causing it to change phase to a gaseous alcohol. A heat exchanger/catalyst is heated by the exhaust to reform the gaseous alcohol into a hydrogen-rich reformate. Valve structure rapidly introduces the reformate into the engine for combustion and a control system is provided for controlling the ratio of the first and second portions of the liquid alcohol to maximize the amount of the second portion of the liquid alcohol while using a minimum amount of the first portion needed to prevent knock. The heat recovery system uses metallic foams on fins heat exchangers.