High-resolution numerical simulations of polymer injection molding are crucial for preventing manufacturing defects during this process. However, the challenges in such simulations are manifold, and efficient high-resolution numerical analysis is still subject to research. In this study, we present a macro-scale two-phase flow formulation for polymer injection molding. We use an in-house finite-element solver to simulate the polymer and air flows as an interfacial flow, utilizing the level-set method in a space-time framework. For a high-fidelity simulation, complex material models are introduced to represent the melted polymer, i.e., shear-thinning viscosity, crystallization, pvT model, and other temperature-dependent properties. We discuss the numerical treatment of the complexities in the model and present the simulation results and performance. This high-fidelity simulation will serve as a benchmark for reduced models applicable to the optimization of the injection molding process.