In four-stroke internal combustion engines the replacement of active fluid in the cylinder is achieved through the periodic opening and closure of the intake and exhaust valves. The valves timing and lift profiles play a fundamental role in terms of engine performance and emissions compliance with the regulations. Valves motion is controlled by the valvetrain system. The mechanism must perform its task in small sizes, without service, quietly, and at low cost. In order to accomplish these goals and identify possible improvements and/or weaknesses during the design phase, virtual simulations assume a key importance. This investigation, carried out under Eaton supervision, is aimed to assess GT-Suite capability of modelling/predicting valvetrain systems kinematic, QDA and dynamic behavior, comparing the simulations results with outputs coming from the design tools currently used by the company and with the experimental measurements.