Three-dimensional numerical analysis for simultaneously developing fluid flow and heat transfer through triangular and sinusoidal channels is simulated in this paper. ANSYS FLUENT 12 was used for simulations. Numerical results were compared with experimental ones for the same channels dimensions. The research was conducted to verify that very short metallic monoliths could be applied to engine pre-turbo catalytic converters. It was shown that short monoliths have high potential to reduce HC/CO emissions due to higher temperatures and flow velocities in front of the turbocharger, resulting in increased heat and mass transfer and reaction kinetics accompanied with reduced flow resistance.