Originally Posted By: Avery4
I would think that you would likely ruin the engine before a fire started. It probably also improves safety to not have a hood on my car(I do not have a hood, funny story about that) because you get more airflow over engine and traps less heat. Correct me if I am wrong.
You're wrong. Or at least potentially wrong.
The vast majority of cooling for a water-cooled engine is through the radiator, which depends on air flowing through the radiator- almost no heat is shed to the air directly surrounding the engine itself. With the hood on, ram air comes in the front of the radiator and exits to the low-pressure area under the car. Cars form a high-pressure aerodynamically at the base of the windshield, which is why "cowl induction" scoops are so effective. Removing the hood can actually make it run hotter, because that high pressure region exposed to the BACK side of the radiator, counteracting the ram air pressure in front of it and making you dependent on the fan to move all the air to keep the radiator cool. When the hood is in place, the back side of the radiator is kept at lower pressure, increasing flow through the radiator and helping the fan, cooling the engine better.