This work proposes an extremely efficient and accurate time explicit solution algorithm for the simulation of contact-impact problems with finite elements. The methodology combines three existent techniques. First, for the treatment of the contact problem, a bipenalty contact-impact algorithm for explicit dynamics with stabilization of the contact constraints through the addition of stiffness and mass penalties [1]. Second, for the reduction of the contact problem to the interface, the method of localized Lagrange multipliers [2], that is able to formulate the contact problem in partitioned form, uncoupling the contact terms from the free body matrices. And finally, for an efficient construction of the free-free inverse mass matrices, the method based on localized Lagrange multipliers to generate inverse mass matrices [3] with specific projectors for the application of boundary conditions. It is also demonstrated that the resultant methodology is very well suited for parallelization in multicore machines. Different numerical experiments will be used to prove the effectiveness of the proposed formulation. 786 COMPDYN 2019 7 th ECCOMAS Thematic Conference on Computational Methods in Structural Dynamics and Earthquake Engineering M. Papadrakakis, M. Fragiadakis (eds.