Charge air cooling, or intercooling the intake air on a turbocharged vehicle is essential to achieving maximum performance. Project Sidewinder uses two intercooling systems to meet the demands of both street and racing operation. On the Bonneville Salt Flats, an air-to-water system was used, but on the street a more conventional air-to-air system does the job.
When it comes to turbocharging, or supercharging for that matter, compressing the intake air to high boost levels raises the temperature of the intake air. On the Land Speed Record attempts at Bonneville, our Project Sidewinder utilized a unique air-to-water charge air cooling system laid out by Bob Robe and Sheldon Tackett. The high-performance Holset® HY55 variable geometry turbocharger used on the Sidewinder for this endeavor heats the intake air to approximately 480-500° F. while compressing it to over 50 PSI boost. Such high intake temperatures greatly reduce the charge density and maximum power potential of the engine unless intercooling is used to bring the temperature back to manageable levels of 100-120° F. Cooling the intake air that much is a challenge. It takes serious heat exchangers and an adequate cooling medium to get the job done. The only practical way to do it is with air-to-water intercoolers using very cold water. And even then, the water flow rate through the intercoolers must be substantial.
With all of the above taken into consideration, Banks® engineered a recirculating water system to intercool the compressed intake air for the Sidewinder's Bonneville runs. The system uses twin Cummins® marine air-to-water intercoolers fed by dual Stewart-E.M.P.® high-capacity electric water pumps. The combined water flow rate is an incredible 120 gallons per minute. The ice water, taken from a custom 40-gallon tank designed by Gale Banks EngineeringTM and assembled by Glenn Lirhus, is located at the rear of the pickup bed. Internal vertical baffles divide the tank into four compartments with alternating bottom and top crossovers to the next compartment. Dual pickups, drawing from the bottom of the fourth compartment, route ice water to the pumps, which are mounted directly to the side of the tank. A horizontal, expanded metal baffle inside the tank prevents any ice chunks from being sucked into the pumps. The water starts out at 33-35° F. and is fed through dual 1-3/4-inch supply lines to the intercoolers. The water, which exits the intercoolers an average of 6° F. warmer than it entered, is returned through 2-inch lines to the tank where it is then forced to flow through the four chambers in the tank to mix with cooler tank water before being picked up and pumped to the intercoolers again. Of course, during a run the average temperature of the tank water rises. The tank water was recooled to 33-35° before the start of each run. The 300 pounds of water weight at the rear of the Sidewinder also helped rear wheel traction on the salt.
Intercooling for the street is less challenging. Because the boost pressures are more conservative, the intake air is not heated as much as in the full race setup. And full throttle operation of the vehicle will be for shorter periods of time. Consequently, a Banks Techni-CoolerTM air-to-air intercooler, positioned in front of the radiator, is used. The Techni-Cooler features a 4-inch inlet and outlet. This is adequate to keep the intake air temperatures to less than 150° F. Besides, on the street, utilizing a recirculating water system, such as used at Bonneville, would be both impractical and unnecessary. Using an air-to-air intercooler also allows removal of 300+ pounds from the rear of the truck to improve both handling and acceleration/braking performance. It also allows the removal of the air-to-water intercoolers, electric water pumps, and associated plumbing.
It is, after all is said and done, a sport truck for the street.