Species concentration profiles produced from pyrolysis of n-heptane and isooctane diluted in argon were measured behind reflected shock waves at temperatures of 1000-1500 K and pressures of 1.2-2.6 atm. Simulation was performed using a chemical kinetic model based on KUCRS. The model reproduced the concentration profiles of n-heptane and isooctane surprisingly well over experimental conditions, while it did not cover some product species. The model was updated including additional species and reactions to reproduce concentration profiles of products.