Charge air temperature needs to be kept low for optimum engine operation. If charge air temperature is too high, engine performance reduction strategies are invoked to protect the engine by limiting the torque available to the driver. A 1D-3D coupling simulation methodology is developed to accurately predict internal air temperature after charge air cooler (CAC) during normal and the most aggressive drive cycles. The 3D flow simulation is used to characterize external air flow before CAC in steady-state cases. Then, interpolated 3D simulation results between steady operating points are used as transient external air boundary conditions in front of CAC in 1D system model. 3D flow simulation is also used to predict internal flow rate ratio between CAC tubes. Finally, 1D system models are used to predict charge air temperature in CAC internal outlet in drive cycles. The validation shows that the prediction errors are within 5 degrees for charge air temperature at internal outlets. This methodology helps inform styling, component sizing & package decisions during the vehicle concept phase avoiding costly hardware changes post tooling kick off. The approach leads to optimized CAC temperatures during all driving conditions yielding full engine torque and increased engine durability.