Disclosed is a turbocharged internal combustion piston engine system that includes a waste-heat recovery system. The waste-heat recovery system involves injecting heated water into the cylinders during combustion to increase engine power and efficiency and to reduce emissions. The engine can be a spark or compression ignition type of engine, and can utilize fuels including but not limited to diesel, natural gas, gasoline, and ethanol. The engine also includes a turbocharger that utilizes a turbine in the exhaust gas flow to provide power to a compressor in the intake air flow to pressurize the intake air and provide additional charge flow to the engine to increase engine output.