Moving beyond the radiator, the rest of the system is just as important. The biggest mistake many gearheads make with their cooling system is the fan. Mechanical fans are just fine, but they eat horsepower and are not controllable. Electric fans are the best option for any car that is not restrained by originality. Regardless of the fan style, all fans should be shrouded, especially mechanical fans. Without a shroud, a mechanical fan is just stirring up the air around it, there is little draw through the radiator at all. With a shroud, the fan generates a vacuum, pulling air into the radiator. This is only important below 40 mph, once the vehicle is moving 40 or faster, the natural airflow takes over.
Electric fans should be shrouded as well. The recommended distance between the fan and the radiator is 1-2”, with a full shroud covering the entire fan-side of the core. This forces the air through the entire core instead of just the area directly in front of the fan. It is very common to see electric fans mounted to a radiator with special zip ties, while this works, it will eventually rub a hole in the core. A shroud is far better, but a fan ring is the suitable solution for tight-fit vehicles where a shroud is less feasible. Fan rings mount to the perimeter of the radiator, eliminating the risk to the core.
While just about every one of us has done it, filling your cooling system with tap water is a terrible option. The minerals in tap water create all kinds of havoc, including sludge, corrosion, crystalline formations, and some even become acidic when mixed with phosphates. Many import coolant formulations such as Honda and Toyota use heavier phosphates, hard water (high in calcium and magnesium) reacts very poorly with phosphates and can severely damage your engine over time. Tap water is also a major contributor to electrolysis in cooling systems. You should only use distilled water mixed 50/50 with the proper coolant. Better yet, you really should consider buying pre-mixed coolant, which ensures that you are getting all the good stuff and none of the bad stuff and you don’t have to mix it. Yes, You are “paying for water,” but it is the right water. Your Brita filter is not good enough; you need chemically pure water to avoid the contamination.
