Self-similar bulk plasmon-polariton modes in quasiperiodic photonic superlattices were used here for a giant enhancement of second harmonic generation. Results for Fibonacci and Thue-Morse-like superlattices indicate that not only the disorder but also the symmetry of the unit cell plays a crucial role for enhancing the efficiency. In particular, a giant enhancement is shown for Thue-Morse-like systems when compared with the enhancement for Fibonacci-like superlattices.