We investigated the effect of energy loss of ions on the ion irradiation-induced tuning of surface plasmon resonance (SPR) wavelength of Au nanoparticles (NPs) in fullerene C-70 matrix. The transformation of fullerene C-70 into amorphous carbon (a-C) under ion irradiation was used to tune the SPR wavelength of Au-C-70 nanocomposite thin films. It is found that the range of tuning of SPR wavelength increases with increase in electronic energy loss of the incoming beam. The growth of Au NPs with increasing fluence was observed in all the cases and total growth is proportional to the electronic energy loss. The average diameter of Au NPs in pristine film is similar to 4.8 nm and a maximum growth of similar to 3 nm was observed at a fluence of 3 x 10(13) ions/cm(2), when the film was irradiated with 120 MeV Ag ions. It was also observed that nuclear energy loss via collision cascades has lower efficiency for SPR tuning in comparison with the electronic excitations.