You could download the last release of OpenModelica, and could start with OMNotebook (for learning the language and API fundamentals) or OMEdit, which has a bunch of component libraries which you can use to model and simulate. Both OMNotebook and OMEdit are installed with the last OpenModelica release binary available to download.

Brunoloes, thank you so much for responding. Once again my question. I can design my engine with Modelica, input the parameters and run simulations on it? Thaks for you help.

Sorry neferkamichael for being late, the notifications are going to my spam.

Yes, OpenModelica is supposed to do what you want: Build multiphysics models, set parameters of model components, and run simulations. This can be done by Modelica code directly and the OMCompiler command-line interface, and also through the OMEdit graphical interface. There is a package for 3D visualization and I think multibody also, but I haven't used them yet.