water pump and pulley selection

Of course, very little has been said here about air flow, which is the biggest part of the equation. If you’re not drawing enough air through the radiator, it doesn’t matter how fast or slow the water is flowing through. Maximizing your air flow is the biggest key to running at temp. The hood to radiator seal and the lower splash pan seal must be in place for the fan and shroud to pull enough air through the radiator. When you’re at a light, air flow is all on the fan, and without sealing the area behind the grille, it’s like sucking through a straw with a hole in it. Same goes for all those pusher fans, forcing air through the radiator with the fan blocking most of the airflow is about the least efficient way to get air through the radiator. There’s a reason the shroud is on the inside, and the fan is close to the outside of the shroud opening, it’s creating a vacuum that pulls air through the radiator. This also causes a vacuum effect behind the grille, and pulls more air through the radiator. It’s like a funnel effect, pour the liquid in the hole and the funnel will not back up, dump it in all at once and it backs up. The water pump regulates the flow, not too fast, not too slow, and the thermostat also does that same thing. The key is airflow.