Steve Baur
Former Editor, Modified Mustangs & Fords
June 24, 2008

Forced induction has the ability to increase power output by 75-150 percent on the average Mustang. As great as that sounds, pressurizing the intake charge does have the side effect of increased intake temperatures, which isn't good for power output. To combat this, Ford, and most supercharging and turbocharging companies, utilize some sort of intercooling method to reduce the intake charge temperature, be it an air-to-air intercooler, or an air-to-water system, such as the one used on '99-'04 Lightnings, '03-04 Cobras, and '07-newer GT500s.

Kenne Bell, one of the most popular Mustang supercharging companies, offers its twin-screw supercharger, which is extremely efficient in its own right. However, the company goes one step further by using an air-to-water intercooler to reduce intake charge temperatures and allow for higher boost and ignition timing levels. Designed for the average enthusiast with a street car, the water reservoir for the intercooler fits neatly in the engine compartment without taking up too much space--a compromise for sure, but effective at its task nonetheless. If your ride is bound and determined to spend the majority of its time at the track, you may want to consider the Quarter-Mile Cooler from HP Performance.

The Quarter-Mile Cooler retails for $650 and comes with a tank, water lines, a water pump and the needed fittings, and a drain valve. A polished version is available for an extra $150.

While completely streetable, the Quarter-Mile Cooler is a large stainless steel reservoir that mounts in the spare tire well of your late-model Mustang, and offers an increase in the water reserve to further lower intake charge temperatures for improved power and performance. It bolsters your supercharger's air-to-water intercooler supply by about 8 gallons--more if you retain the original supply reservoir. The reservoir opening is large enough that you can pack it with ice to get the intake temperatures down really low, and the kit comes complete with the tank, lines, and water pump for $650. Some may question the weight penalty of adding 8 gallons of water to your car, but consider that it couldn't be in a better place than right behind the rear axle, which should increase traction.

"When we were building John McGuire's '04 Mustang, we discussed installing a tank in the spare tire well of the car," says HP's Tony Gonyon. "John gave the idea to his brother-in-law, and he designed the cooler from the dimensions of the spare tire. Once he built the first one, we tested it in John's '04 GT and saw inlet temps drop almost 28 degrees right at the start to the finish of the pass. That allowed another 2-3 degrees of timing, which made another 30 hp. On one pass, we went from 450 to 494 rwhp."

We followed along as HP Performance installed one of its coolers in an '05 Mustang GT equipped with a Kenne Bell supercharger. Said Mustang belongs to Jason Cook of Ludiwici, Georgia, and in addition to the supercharger, the Mustang also sports long-tube headers, an x intermediate pipe, and a 4.10 rear gear change.

Our subject vehicle for this test is an '05 Mustang GT belonging to Jason Cook, of Ludiwici, Georgia, and features a Kenne Bell twin-screw supercharger and air-to-water intercooler. Other mods include long-tube headers, an off-road pipe, and 4.10 gears.

"Jason drove down from Georgia a few months back, and we retuned it from the Kenne Bell tune of 379 hp to 425 hp," Gonyon says. "His inlet air temps were approaching 150 degrees, so I suggested installing our Quarter-Mile Cooler, which we had tested and seen over 30-degree temperature drops."

With the added capacity of the Quarter-Mile Cooler, the average intercooler water temperature dropped approximately 25 degrees, which allowed for either more ignition timing or more boost. Since the computer alters the timing for different atmospheric conditions, more boost was added, with a smaller 3.25-inch supercharger pulley. The added 3 psi of boost, which now totaled 11 psi, along with a few keystrokes in the SCT custom tuning software, produced 461 rwhp and 425 lb-ft of torque at 119-degree inlet air temperature.

This is with the intercooler coolant at an ambient air temp of about 70-80 degrees. Unfortunately, we didn't have time to test the system with a cool tank of ice water, but we've tested the effect of circulated ice water on supercharged Cobras before, and have seen about 30 hp above using ambient-temperature fluid, so there's still some horsepower to be released should you seek to achieve maximum elapsed times.

Keep in mind that the Quarter-Mile Cooler can be used in place of most all air-to-water intercooler applications. Cooler intake temperatures have been the key to late-model performance since the first bag of ice was placed on a 5.0 intake. These days, components like the Quarter-Mile Cooler just let you take the bag with you down the track and down the street.