Hot summer days and the warm nights that follow are practically made for cruising. There's nothing better than hopping in your car on a Saturday night and rolling down to the local Cruise 'n' Chew to hang with some friends and talk about cars 'till dawn. But nothing can ruin that more than pulling into your favorite parking spot with a puking radiator and all your buddies laughing at you. That's the bummer of summer. There is a solution, however, and it's easier and cheaper than you might think. Staying cool isn't hard these days and we've got the tips to keep you in the sub-zeros.
Cool PumpingWith so many advancements in water pumps today, it's no wonder they're so often misunderstood. The first thing to remember about the water pump (more correctly referred to as a "coolant" pump in this case) is that it only moves the coolant around. A coolant pump, by itself, will not help or hurt cooling, that is unless it can't do its job (i.e. pump coolant) fast enough. The reason a coolant must pump fast is because there's a lot of thermal heat exchange going on inside the engine.
It's the coolant's job to extract the heat from the engine and transfer it to the heat exchanger, which in an automobile is the radiator. If the pump cannot move enough coolant quickly, not enough heat will be pulled out of the engine and it'll run hot all the time. But this ties into several other areas that'll we'll address in a bit. Just remember that the only thing a coolant pump does is pump coolant.
You can, however, gain some horsepower with the proper coolant pump. And you might run cooler after installing the right pump, but only if your old pump couldn't keep up with demand. The author participated with Weiand Automotive Industries in the mid-late '90s developing a coolant pump testing program to be used with their coolant pump dynamometer (the only such unit in existence at the time). They dyno-tested and compared flow capacity and horsepower consumed between different factory and aftermarket pumps. It was found that most stock pumps could flow up to about 50 gallons of coolant per minute (gpm) at a standard test pressure of around 13 psi (flow capacity usually goes up as pressure is increased, due to less cavitation on the impeller). To move those 50 gpm a stock pump consumes an average of more than 10 hp.
The high-efficiency pumps Weiand was developing at the time consumed half that amount and flowed more than twice the coolant! That same technology has been engineered into most aftermarket performance pumps today, but there are some low-speed pumping sacrifices you'll also suffer with most of these pumps. Generally, if you're planning to do nothing but cruise down the boulevard or open highway, you'll actually do well to run a standard pump (Weiand has made standard-style, aluminum replacement pumps for years). But if you're going to make some horsepower and push your car hard on the road, you should opt for a high-performance pump like the Weiand Team G or Edelbrock Victor series.
The Radiator's Job Is To CoolThe radiator does the cooling. There's no other reason to have one. But if your radiator is too small or cannot move the necessary amount of coolant through it fast enough, your car will run hot, guaranteed. Before the widespread use of aluminum radiator cores in OEM applications, it was unusual to see an aluminum radiator in a hot rod. If someone needed to cool his or her car down, a large, heavy, multi-row brass/copper radiator was specially constructed.
The thinking was "the bigger the radiator core, the better the cooling." Well, it's been proven time and again today that a big core is not the key to cooler engines. Yes, moving a large amount of water through the radiator will cool things down, but only if air can get to all the cores. That's because a radiator is simply a big liquid-to-air heat exchanger, and air needs to get to all parts of the heat exchanger in order to cool it efficiently.