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Chevy Radiator & Waterpump - Stay Cool

Some Cooling Tips To Keep You Below The Boiling Point

Mike Petralia Sep 1, 2002
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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 Pumping
With 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.

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Impeller designs in today's high-performance water pumps (this one is from Evans Cooling) make them practical for almost all high-performance motors. They'll flow more than twice the coolant of a stock pump while using only about half the horsepower.

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.

Sucp_0209_02_z Chevy_radiator_waterpump Waterpump 4/13

Electric or mechanical, which is better for you? The answer is mechanical for anything but a drag-only car that does not see street duty.

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 Cool
The 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.

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Under-drive pulleys were once all the rage. It's been found that slowing the water pump down is not good for high-performance driving. Unless your car is a quarter-mile dragger only, keep the water pump spinning at the factory overdriven speed. Save horsepower by getting a high-flow water pump instead.

The problem with thick, multi-core radiators is that by the time the air gets to sixth or seventh core in the back, it's already as hot as the cooling fins it's touching and therefore cannot remove any heat from them. Also, it's harder to push air through those thick cores, and the faster you drive, the more air gets pushed around the radiator from the "air dam" that builds up in front of it.

The best way to cool a powerful engine today is with a dual-core aluminum radiator featuring 1-inch-or-larger tubes. And since you'll save weight with an aluminum radiator, there's no real drawback to running one. They're not even that expensive when compared to the cost of a new (not re-cored or rebuilt) brass/copper radiator. And companies like Be Cool, Griffin, Howe, Fluidyne, and others have made it easy to swap an aluminum one into your car.

Blowin' Cool
The fan is the last thing you want to rely on to keep you cool. In fact, fans are only used on cars because we can't always be driving around at 40 mph, at which speed there's enough air moving through the radiator to keep it cool. While it's true that a big mechanical fan will move the most air and, therefore, have the best cooling capacity, we've found that the horsepower consumed by a fan can easily be regained with installation of dual electric puller fans.

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Running a 180-degree thermostat in almost any street car will keep it cool. Drill one or two 1/8-inch holes in the thermostat as shown to purge air from the motor when filling the system and as it warms up.

We specify puller fans because trying to push air through a radiator with a fan in front of it does very little good. And you never want to run a pusher electric fan on a radiator that has a mechanical puller fan behind it; they'll sort of cancel each other out and you'll run hot. The best way to keep cool and save power is to get a big dual electric fan setup from a company like Flex-a-lite and mount it on the back of your radiator. Fabricate some sort of shroud to direct as much air as possible through the fans and you'll run even cooler. Just make sure to hook up the thermostatic control for the fans; otherwise you'll be wasting energy driving down the highway with your fans running.

Thermostat's Where It's At
Think of the thermostat as a tiny little guy working a control valve in your engine. The Captain up in the control tower monitors engine temperature in the block. It gets too warm and he radios to our little guy, asking him to open the coolant valve to allow flow into the heat exchanger. The air cools the water and it flows back into the block to cool the engine down. The Captain now tells our little guy to close the valve so the coolant can absorb more heat from the engine and prepare to dissipate it in the heat exchanger. That's all the thermostat does.

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Unless you're running Evans NPG coolant, you can increase your boiling point by raising the system pressure with a radiator cap like this 22-24 pounder from Howe (above), since water boils at a higher temperature when it's under pressure. Make sure your hoses and seals are in top shape before you do this.

It opens when the coolant reaches a pre-set temperature and allows coolant to flow into the radiator. It closes when things are cool, allowing the coolant time to absorb heat from the block and heads and haul it off to the radiator. If you remove the thermostat, most likely your engine will run hotter because the coolant does not spend enough time in the engine block and cylinder heads to pull enough heat out. And since the cooling system is just one big closed-loop component, the coolant won't spend enough time in the radiator to cool down either when there's no thermostat in the engine. Most street cars will run best with a 180-degree thermostat, not a 160 like old-timers like to preach.

Some other basic ways to keep cool are by fabricating a fan shroud for all radiators. Also, creating ducting to direct air from the grille into the radiator like they do in NASCAR is worth a big-time temperature drop. Of course, no engine likes to breathe hot air, so anytime you can route cool, outside air into the engine with ducting or a sealed cowl-induction hood, you'll increase power, too. But that won't make your engine run cooler.

Header wraps, fuel line insulators, and things like that won't make you run cooler, but firewall insulation from companies like Thermo-Tec will keep your interior at a more comfortable level, so it's worth looking into. Basically, you can have your power and stay cool making it if you just combine the right components and don't fall victim to the "drag racer" mentality of under-driving everything or the "old timer" ideals like thinking a bigger brass radiator is better. Few people give credit to how much new cooling system technology has allowed all of us to make more reliable power than ever before. There's a science to staying cool, and fortunately, you don't need a degree in refrigerant technology to practice it.


Fife, WA 98424
Weiand Automotive Industries
Mira Loma, CA 91752
Greenwich, OH 44837-9526
Fluidyne Racing Products
Ontario, CA 91761
Evans Cooling
Parkerford, PA 19457-0434
Howe Enterprises
Beaverton, MI 48612
Stewart Components Brake Development
High Point, NC 27262



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