This paper addresses the problem of predicting timing properties of multi-tasking component assemblies during the design phase. For real-time applications, it is of vital importance to guarantee that the timing requirements of an assembly will be met. We propose a simulation-based approach for predicting the real-time behaviour of an assembly based on models of its constituent components.Our approach extends the scenario-based method in [Prediction of Run-time Consumption in Multi-task Component-Based Systems] by offering a system model that is tailored to the domain of real-time applications. Contributions of this paper include the possibility to handle the following features: mutual exclusion, combinations of aperiodic and periodic tasks and synchronization constraints. The analytical approach we used in previous work cannot handle these features. Therefore, we introduce the simulation-based approach.Our simulator provides data about dynamic resource consumption and real-time properties like response time, blocking time and number of missed deadlines per task. We have validated our approach using a video-decoder application.