This invention relates to a fuel activating device and method consisting of at least two separate infrared-emitting bodies, each infrared-emitting body being engineered to have specific peak wavelength and spectral luminance in 3-20 um (micrometer) wavelength range, that provides an effective means for enhancing combustion of hydrocarbon fuels in internal combustion engines, resulting in better engine performance with increased power, improved fuel economy, and reduced emissions.