Modifying Radiator Flow
In my first round of measuring pressures across radiators , I found that small amounts of grill blocking can significantly reduce cooling airflow through heat exchangers, and that the optimization of engine bay flow in more modern cars can have a major effect on the flow through radiators. My older truck had less than half the pressure differential across its radiator than my Prius had through two stacked radiators (one in front of the other), and the instantaneous pressure readings in the truck jumped around a lot while in the Prius they were stable. ETA 3/9/2026: Since writing this, I've completed an aerospace engineering degree and, as one of my first projects after graduating, I've gone back to revisit cooling system performance. For in-depth analysis and instructions on what to measure on your car, see: Measuring and Improving Cooling System Performance – Part 1: Overview Measuring and Improving Cooling System Performance – Part 2: Inlet Measuring and Improving Cooling Sy...