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' CoolThe 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.
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 AtThink 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.
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.