In addition to the airflow, the supercharged motor obviously requires additional fuel. For the modern EFI Hemi, this should be as simple as reprogramming the ECU, right? Unfortunately, reprogramming the factory ECU has become more and more difficult, especially with the advent of drive-by-wire throttle activation. Naturally, the Chrysler engineers programmed all manner of safety devices to prevent the electronic throttle body from sticking in the WOT position and allowing the car to accelerate away under full throttle. Changing the fuel (and timing) values is not terribly difficult, but getting around the throttle and torque-limiting strategies is considerably more so. Lucky for enthusiasts, the guys at Kenne Bell are one of the few companies that have successfully conquered the Chrysler Hemi (drive-by-wire) programming. Changing the fuel and timing parameters was only part of the equation, as the stock fuel pump and injectors were not designed with the elevated power levels offered by the supercharger in mind. The Kenne Bell kit included a 17V Boost-a-Pump (BAP) to enhance the flow rate of the stock fuel pump, while the factory injectors were replaced by a set flowing 50 lbs/hr. According to Kenne Bell, the fuel system upgrades to the Hemi will support up to 650 rwhp. Additional power can be had with a 20V Competition BAP and 75-80 lbs/hr injectors.
These air and fuel upgrades applied to the Hemi are actually pretty universal in terms of application, but Kenne Bell also applied a few other Hemi-specific tricks to their supercharger kit. First off was a cure to the PCV system. Stock Hemis rely on an elaborate oil control system to eliminate oil from pooling in the intake tract and winding up being burned in the combustion chamber. Since the Kenne Bell supercharger kit replaced the factory intake manifold and attending PCV system, it was necessary to come up with a suitable replacement. The cure was to design a dedicated oil control valve that increases horsepower while reducing detonation and oil consumption. Oil vapor is easily ignited (even more so than gas vapor) and as such can be the source for harmful detonation. Kenne Bell also had to solve the common surge and runaway throttle commonly associated with supercharged Hemis. Their cure was to design a new bypass valve, a design so revolutionary that they decided to patent it. The patent-pending Boost-Vac design reduces supercharger heat, improves mileage, and even works well with non-stock cams (where erratic idle and cruise vacuum reading play havoc with typical bypass valves). Combine these tricks with a set of detailed instructions, extensive R&D, and first-rate tech support and you have an impressive upgrade for any Hemi.
To illustrate the gains offered by the installation of the Kenne Bell kit on an '09 Challenger, we followed along during the installation and subsequent dyno testing. Naturally the first order of business was to baseline the Challenger in normally aspirated trim prior to the installation of the supercharger. In bone stock trim, the automatic 6.1L Challenger produced 342 hp and 337 lbs/ft of torque. The manual version did slightly better, as the stock six-speed Challenger produced 376 hp and 375 lbs/ft of torque. After adding the Kenne Bell supercharger kit, these numbers jumped to 515 hp and 472 lbs/ft of torque for the auto and 537 hp and 510 lbs/ft for the stick. All this glorious horsepower came at just 8 psi of boost, but we understand that replacing the 3.5-inch blower pulley with a smaller 3-inch version will increase the boost pressure to 12 psi and the peak power numbers to an even 600 hp. Every bit as impressive is the fact that this requires no revised tuning, only the use of higher octane fuel. Know that Kenne Bell has taken an otherwise stock 6.1L Hemi to the maximum with the installation of an 8-inch crank pulley (replacing the stock 6.25-inch) and a 2.75-inch blower pulley. Additional upgrades included the Kenne Bell throttle body upgrade (flows 1880 cfm), a 20V BAP, and 80 lbs/hr injectors. Equipped as such, the blown Hemi Challenger from ST Motorsports produced 765 rwhp (near 900 engine horsepower) and ripped through the quarter-mile in a blazing 10.25 at 131 mph (equipped with slicks). Much has been written about the weak factory Hemi pistons, but these results demonstrate that it is obviously possible to produce exceptional power with proper tuning and Big Bell Boost.