Internal combustion engines face increased market, societal, and governmental pressures to improve performance, requiring researchers to utilize modeling tools capable of a thorough analysis of engine performance. Heat release is a critical aspect of internal combustion engine diagnostic analysis, but is prone to variability in modeling validity, particularly as engine operation is pushed further from conventional combustion regimes. To that end, this effort presents a comprehensive open-source, zero-dimensional equilibrium heat release model. This heat release analysis is based on a combined mass, energy, entropy, and exergy formulation that improves upon well-established efforts constructed around the ratio of specific heats. Furthermore, it incorporates combustion using an established chemical kinetics mechanism to endeavor to predict the global chemical species in the cylinder. Future efforts can augment and improve the chemical kinetics reactions for specific combustion conditions based on the radical pyrolysis of the fuel. In addition, the incorporation of theoretical calculations of energy and exergy based on the change in chemical species allows for cross-checking of combustion model validity.