KB Supercharger Adds 270-hp to 392 HEMI

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KB Supercharger Adds 270-hp to 392 HEMI

Postby scottm » Sat Oct 07, 2017 11:19 pm

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We add a Kenne Bell Supercharger to a 392 Dodge Challenger and pick up more than 270 HP!
http://www.hotrod.com/articles/we-add-a ... an-270-hp/

Not that long ago, a Hemi owner packing 485 hp had little to worry about on the street. The power output of the 6.4L (392-inch) Hemi bested all the normally aspirated offerings from both Ford and Chevy. With the greatest displacement came an abundance of torque, so the owner of a Hemi-powered Challenger could hold his (or her) head high when talk turned to performance. After all, they already had the best-looking modern muscle cars! Time and technology marched on, and though plenty potent, the normally aspirated variants offered by the Big Three were soon displaced by their boosted big brothers. Ford offered the Shelby, GM the LS9s and LT4s, and Dodge jumped in with the impressive Hellcat versions, then upped the ante with the new Demon. Suddenly, the 485-hp 6.4L seemed a tad inadequate. The question now is: in a world of 600hp, 700hp, and now 800hp production muscle cars, what is a run-of-the-mill Hemi owner to do?

The answer to this is the same one that solves every performance problem—just add boost! The new Hellcat and Demon are proof positive that Chevy and Ford don’t have a monopoly on factory forced induction, and the modern Hemi is every bit the boost-loving machine when properly applied. To illustrate the benefits of boost, we followed along while the gang at Kenne Bell installed their emissions-legal supercharger kit on a 2016 6.4L Challenger. Kenne Bell was quick to point out they also offer a number of kits for other 2008-2017 Dodge vehicles equipped with 5.7L, 6.1L and 6.4L Hemis. They also noted that the increased static compression, combined with the sophisticated knock-sensor calibration utilized in the latest 6.4L, required a slight drop in boost compared with the previous 6.1Ls.

Applied to the 6.4L, the kit encompasses a 2.8L twin-screw supercharger, high-density, air-to-water intercooler, and Mammoth intake manifold. Also included are a 4.5-inch (true) cold-air intake system, a new set of injectors, and Kenne Bell Boost-a-Pump. The key to the success of the supercharged Hemi is a dedicated (reflash) tune, the result of endless hours of research and development.

Before getting to the results, a review of the components is in order, if for no other reason than to illustrate the potential of these parts. The crown of the system is obviously the highly efficient twin-screw supercharger itself. The standard kit offers a 2.8L unit (available satin or polished) that features an industry-leading 4×6 rotor pack; less-restrictive, rear-feed induction; and patented Liquid Cooling. Not to be confused with intercooling, which the Kenne Bell kit also employs, Liquid Cooling refers to the introduction of a cooling medium to the hot side of the blower in order to equalize the temperature of the case. Case distortion is a function of temperature, and on any blower featuring internal compression, there will be a temperature differential between the cool inlet, and the heated discharge sides of the blower. Liquid Cooling was designed to minimize this effect. As a bonus, it helps keep the front gear case oil cool, and increases bearing-seal life. Though Kenne Bell offers larger superchargers (displacing up to 4.7 liters), the 2.8L is sized perfectly for the application and capable of supporting more than 1,000 hp. The standard 2.8 is also larger in displacement than the factory blowers employed on the both the Hellcat and Demon!

Mention the phrase inlet restriction to the guys at Kenne Bell, and watch them cringe. No supercharger, even an efficient twin-screw, can realize its flow and power potential if choked off by restrictions in the intake system. In this case, the intake system includes everything in front of the supercharger, including the manifold, throttle-body, and air-intake assembly. Recognizing the inherent restrictions that limit power potential, the gang at Kenne Bell designed an intake system capable of feeding their 1,000-plus hp superchargers. The Hemi Challenger kit includes a dedicated Mammoth intake manifold, 4.5-inch cold-air inlet. The kit was designed to accept the factory 81mm Hemi throttle-body, but swapping out the adapter plate allows installation of an even larger, 148 mm drive-by-wire throttle-body upgrade. The simple fact that a bigger throttle-body exists meant we had to test it, right? While the standard 6.4L kit features a blower pulley that produces a peak of 6.5 psi, we liked the fact that the rest of the components were ready and willing to pump out up to 1,000.

According to Kenne Bell, reduced parasitic losses associated with driving the twin-screw blower allows the use of a six-rib, serpentine drive belt for the blowers and factory accessories. This same drive system has been run successfully on 9-second, supercharged stroker applications exceeding 800 hp at the wheels.

Obviously, the stock Hemi fuel system is not up to the task of feeding the additional power, so the Kenne Bell kit includes a set of 50-pound injectors. The factory fuel pump was then augmented with Kenne Bell’s 17-volt, Boost-a-Pump to supply the necessary fuel flow. According to specs, this combo will support a bit more than 700 hp at the wheels, while larger injectors and a 20-volt Boost-a-Pump can increase the power potential to roughly 775 hp at the wheels. If you want more, you will have to step up to additional fuel-system upgrades.

Naturally, we baselined the Challenger prior to installation of the blower, and in stock trim, the six-speed 6.4L produced 434 hp at the wheels. Now it was time for boost. With the supercharger and accompanying components installed, the Challenger was back up on the dyno and ready to roll. After flashing the new program, the Hemi fired immediately, and we were back in business- the business of boost, that is! As good as the Hemi Challenger sounded in stock trim, the supercharged version sounded even meaner. After the warm-up, we ripped into the throttle and were immediately rewarded with a jump in power to 550 hp at the wheels. Even limited to just 6.5 psi, the Kenne Bell supercharger improved the power output of the Challenger by 122 hp, but we were just getting started. More power was simply a pulley swap away, and each additional pound of boost brought a hefty chunk of power. Running 7.5 psi brought 576 hp, which jumped to 615 hp at 9 psi, then to 667 hp at 11 psi. The final step was to replace the 81mm throttle-body with the 148 mm unit, which pushed the peak numbers up to 708 hp. Naturally, we performed the fuel-system upgrade (and mixed in some race fuel) in anticipation of the elevated boost levels on our test mule. It was amazing how easy adding all the power was.


Maybe one of these KBs is what my RAM needs to get me over 500-hp! 8)

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