A turbocharged engine system (500) is configured to vaporize methanolin a heat exchanger (350) using heat from exhaust gases, and uses the vaporized methanol to drive a turbine (361) of the engine's turbocharger (316, 519,124, 126). The methanol may also be dissociated into hydrogen and carbon monoxide. After passing through turbine (316), the vapor is injected into the engine (102) by port injection. By selective timing of exhaust valves (472, 474), the exhaust gases are separated into two streams (409, 410), a first stream comprising gases ejected during exhaust blowdown, and a second stream of gases ejected during the remainder of the engine's exhaust stroke. The blowdown gases are employed to drive a separate turbine (519) of the turbocharger (316, 519, 124, 126).