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No, this isn’t about WWII, but it does have ties to the second world war. Intercoolers are radiators, just like the one in front the engine in any water-cooled vehicle, but instead of cooling liquid, they cool air. While supercharging had been around for about 50 years, during World War II, warplane manufacturers were adding superchargers and turbochargers to aircraft engines. The legendary Rolls Royce Merlin 61 engine was fitted with two superchargers in 1942, and the engineers quickly realized that they needed to cool the incoming air charge. To solve this, they developed a heat exchanger which used cold air from outside the aircraft to pass through the fins, cooling the pressurized air inside. They also added a second unit to cool the air coming out of the second supercharger. This is the genesis of the air-to-air intercooler we use today in supercharged cars.
There are two main types of intercoolers used in vehicles: air-to-air or water-to-air. Unlike a coolant radiator, the point of an intercooler is to drastically reduce the temperature of the boosted air. Both blowers and turbos generate a good amount of heat, and hot air doesn’t have as much oxygen, and therefore less potential energy compared to the same volume of more dense cold air.
This is a 1963 Buick LeSabre wagon with a twin-turbo Buick 350. The turbos are hot air, as they are plumbed directly to the carburetor. This configuration made over 600 lb.-ft of torque, but it was limited to 6 psi of boost due to detonation. It really needed an intercooler to take full advantage of the turbochargers’ capability.Photo: Jefferson Bryant
Water to air intercoolers do not use engine coolant like transmission or oil coolers, instead they run their own complete cooling system. It is more complicated to design and setup than air-to-air systems, but it is the only way you can cool a Roots-style supercharger that sits on top of an engine. This is commonly used by GM, Ford, and Dodge, positioning a water-to-air intercooler under the blower. Race teams often use water-to-air intercoolers too, but instead of just running coolant through the system, they run ice-cold water from an ice tank.
Air-to-air intercoolers are far more common and are typically used in centrifugal superchargers and turbos systems. These mount in front of the radiator at the front of the vehicle, or such as the Subaru WRX, on top of the engine with a hood scoop to direct cool air through the heat exchanger. These coolers are very efficient and can raise the output of your engine significantly. It is noted that a 10-degree drop in air temperature can yield 1% more power output. A turbocharged 500-hp engine with an intercooler can see 30-degrees cooler air than a comparable hot-air turbo car, which means you can get 15 or more horsepower just by adding the intercooler. In turn, you can tune the engine a little further, to eek out as much power as possible.
This is the layout stage for the intercooler installation on the 1962 Comet. The core on the right doesn’t have air tanks – this is to let the builder configure the pipes to best fit the application Photo: Jefferson Bryant
The other side of the coin is adding boost to a stock engine not designed for boost. This puts more pressure in the cylinders, and that pressure can cause detonation, eventually damaging the engine. With an intercooler, you can run more boost safely, as the detonation factor is reduced by sending cooler air into the engine. Intercoolers are the best thing you can do for a boosted system.
The design, size, and build quality of the intercooler is an important factor in choosing what you need for your application. A single pinhole in an intercooler can bleed off pressure, reducing the output of your engine. Cooling fins that are too thick, too far apart, or too close together affect the flow of the cooler, reducing efficiency. This is where U.S. Radiator can help. They offer several universal fit designs but can also build custom intercoolers to fit your vehicle.
Once the Comet’s layout was finished, the air box was connected to both sides of the intercooler. Boost was joined together inside of the air box, which is where the blow-off valve was located (at the rear bottom of the air box).Photo: Jefferson Bryant
U.S. Radiator uses the same processes and materials to build top-quality intercoolers as they do their radiators, so you know if you have a U.S. Radiator intercooler, it is going to provide the best efficiency for your money. Adding a cheap overseas intercooler can actually do more harm that good. If flow is restricted or boost leaks out, you will lose power instead of gaining it. Even more important for turbo systems is potential loss of pressure, as a turbo can over spool if the boost is not controlled, allowing the turbo to spin too fast and burn up. Quality matters when it comes to building power. Call U.S. Radiator at 800-421-5975 to discuss your intercooler needs with their knowledgeable staff. Remember: boost is good, but cold boost is best.