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Supercharger Shootout - Brothers In Arms
In This Supercharged Slugfest, We Find Out What 20 PSI Of Boost Is Worth On An '03 Cobra, An '05 GT, And A Shelby GT500.
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With huge power gains just a blower-pulley change away, why on earth would anyone want to replace the factory supercharger on an '03-'04 Cobra? The answer is actually quite simple, as the limiting factor in terms of power production is the supercharger itself. We know from experience that the remainder of the 4.6L Four-Valve motor will withstand a great deal more power, but there is only so much fl ow and power potential hidden inside the factory Roots-style blower.
To extract even more power from the Terminator combination, a blower swap is in order. Obviously, it's also possible to install turbos on the motor, but that's a subject for another story. By now, replacing the factory Roots-style blower on the Cobra has become commonplace, with upgrades from a variety of sources, including Kenne Bell, Whipple, and Eaton TVS. Given Cobra owners' insatiable thirst for power, the blower experts at Kenne Bell configured not only a more efficient twin-screw supercharger design, but one that offered significantly more displacement and therefore more power potential compared to the factory huffer. Where the original blower might be considered a 600hp supercharger, the 2.8L H-configuration twin-screw has already exceeded 1,100 hp on the right application. Think about those figures for a minute. This 2.8L H-series supercharger offers nearly twice the power potential of the stock blower. No wonder these blower upgrades are so popular among Cobra owners.
For our test, the '03 Cobra motor was run through the factory exhaust manifolds and cats feeding a Bassani after-cat exhaust. To keep the testing consistent, all three test vehicles were equipped with a Bassani performance after-cat exhaust. In addition to the Kenne Bell 2.8L H-series blower, the Cobra was upgraded with a dual Boost-a-Pump feeding the stock injectors and a Mafia to eliminate topping out the MAF signal. All three test motors were also equipped with a free-flowing inlet system in front of the supercharger, including a dual 75mm throttle body, a 4.5-inch inlet tube and mass air meter, along with the oval fl expipe from the Ford GT.
Naturally, the 2.8L blower was fed using a new Mammoth intake manifold. In short, every effort was made to eliminate inlet restrictions that would limit the power potential of each combination. Combining a 7.5-inch crank pulley with a 3.25-inch blower pulley (a 2.30 drive ratio) resulted in the desired 20 psi of boost. Tuned to perfection on race fuel, the combination produced 702 hp and 578 lb-ft of torque. Can you imagine what kind of fun you could have with a Cobra making that much power?
'05-Up 4.6L GT
704 HP at 6,500 RPM
607 LB-FT of Torque at 4,700 RPM
Pulley Combination 6.5 Crank/3.00
Blower (2.17 DRIVE RATIO)
What car combines the good looks of a '69 Mach 1, the performance of a 428 Cobra Jet, and the driveability and comfort of a modern car? The answer is the '05-up Mustang GT. The retro-modern styling obviously ranks high on the cool scale, and the amount of mods one can make is matched only by the Fox-body Mustang.
Were the new Mustang a less-than-stellar success, Chevy and Dodge wouldn't have been so quick to jump on the nostalgia bandwagon with the yet-to-be-released Camaro and Challenger models. Now more than three years old, the GT still looks great, especially decked out in stripes and spoilers. Sporting near-Cobra power (naturally aspirated, of course), is a 4.6L Three-Valve motor with variable cam timing. This new modular motor nearly matches the output of the older Four-Valve Cobra motors using one less valve per cylinder. The only problem with the new GT is that the impressive Three-Valve motor has to push a ton of extra weight. The Mustang GT has bulked up considerably since the days of the 5.0L, and all that weight takes a toll on performance.