Michael Galimi
December 31, 2009

Why does a longer intake runner provide better low-end than a shorter one? Simons explained the concept as it pertains to a naturally aspirated combination, "As the intake valve closes, a pressure wave reverberates back up the intake runner. As that pressure wave reaches the plenum, it rebounds back toward the valve. If the valve happens to be open when the wave is traveling back down the runner, then air is rammed into the combustion chamber with greater momentum due to the inertia of the wave itself. The speed and frequency of the wave is much faster than that of the valve cycle, so not every wave can be taken advantage of, however, the longer the distance the wave has to travel, i.e. the longer the runner, the larger the wave intervals, and the lower the engine rpm at which the intake valve opening sequences with a multiple of the wave frequency. A shorter runner results in a faster wave frequency, and it is not until a much higher rpm at which the engine is able to take advantage of this energy source."

The same pressure wave reverberation occurs in supercharger applications as well. "Now it would be naive to assume that this phenomenon is completely unchanged in a forced induction application. The positive pressure in the manifold certainly has an effect on the wave behavior, however instrumented testing shows that the wave still exists. A pressure transducer located inside of the intake runner, and monitored at a high log rate, will capture the peaks and valleys in the boost pressure curve-due to this reverberating pressure wave. The benefit of this system optimization can easily be seen on the dyno. While a stock 4.6L Three-Valve Mustang engine has a torque peak at approximately 4,800 rpm, an E-Force supercharged Mustang engine sees its torque peak at only 4,200 rpm. Most competitive supercharger kits, utilizing short intake runners, likewise see a later torque peak of around 4,800 rpm," inserted Simons.

In addition to the long-runner manifold, Edelbrock also built a special cast housing to allow the lobes to be fed from the front-side, but also with it using a front blower-drive system. This design varies from other Eaton-based systems that have one or the other. If front-fed, the supercharger usually utilizes a jackshaft to spin a rear-mounted pulley system. Other TVS blowers use a front-driven setup but rely on the air to be fed on the backside, where there is a little room behind the blower to get a decent-sized inlet manifold between the housing and firewall. Plus, the incoming air has to make a 180-degree turn, which can hurt flow.

One part that Edelbrock includes is an 85mm throttle body, which is round for better packaging. The throttle body is typical with an electric motor for the drive-by-wire system employed on the S197 Mustang. The large manifold relocates many sensors and the fuel injector positioning. To remedy the plug connection problem, Edelbrock includes several wiring harnesses to make this a complete plug-and-play setup.

Once attached, the supercharger blows into a 110-square-inch intercooler before it passes through the 15-inch runners into the cylinder heads. The complete Edelbrock system is 50-state legal when installed out of the box. Like most Edelbrock products, it's proudly made in the USA.

The company sells a complete system, but we followed JDM Engineering as the New Jersey-based Ford performance shop bolted the Competition Kit to an '08 Mustsang GT with a five-speed manual transmission. The E-Force Competition system comes as a barebones setup so shops can add their own stuff. JDM chose to install its own fuel system and custom tuning. The shop uses SCT software, and D'Amore prefers to run the car on the dyno and then road test to ensure the tune is right for each particular vehicle.

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