Designing a car radiator involves understanding key factors such as size, cooling efficiency, and material choice, particularly for a race car with limited space. The discussion highlights the challenge of sourcing affordable aluminum radiator components, as commercial options can be expensive. Participants are encouraged to share resources for DIY radiator kits and aluminum cores, which are essential for custom builds. The need for welding tank ends onto cores is also emphasized, indicating a preference for a hands-on approach. Overall, the thread seeks practical advice and sources for creating a customized aluminum radiator.