By Richard Holdener
Sometimes, it is great to take a look back at performance vehicles of yesteryear, if for no other reasons than to see how far we have come. The side benefit is that owners of said vehicles are also treated to a reminder their chosen mount is still relevant and, more importantly, how they can make it even better.
For this trip, we set the Way-Back machine to Y2K. You remember, when the end of the world was coming because all the world’s computers were set to simultaneously shut down , sending us all back to the analog age. Once we said goodbye to 1999, and officially ushered in the year 2000, the hottest performance car offered by Ford was actually a truck. Thanks to the boys at SVT, the supercharged Lightning featured not only increased displacement, compared to the 4.6L Cobras of the day, but factory forced induction. We would later see this applied to the four-valve Cobra in 2003, but for now, the two-valve Lightning was a Chevy stomper of the highest order.
Produced from 1999-2004, the 5.4L employed in the Lightning offered 360 hp in the early models (1999-2000), but this was upped to 380 hp in the later versions. Credit for the horsepower increase (and extra 10 lb-ft of torque) went to a larger air intake and revised lower intake manifold. As impressive as Ford’s little wonder truck was in stock trim, what really made the Lightning appealing was the how it responded to modifications.
Naturally, Ford took a conservative approach to tuning on the supercharged V8, but given the low compression (8.4:1) employed on the blower-specific mod motor, the Lightning mill was certainly capable of producing considerably more power. Lightning owners soon found the motor would respond to the usual array of performance mods, like air intakes, tuning, and exhaust mods (more so than their normally aspirated counterparts), but what really added power was more boost. Pulley swaps on the Eaton M112 (112c.i. or 1.84L) supercharger netted impressive power gains, but the limiting factor eventually became the flow capacity of the blower itself.
To illustrate the gains offered by replacing the factory Eaton supercharger on the 5.4L Lightning, we first ran a Lightning with the stock Eaton supercharger. In fact, we ran our supercharged 5.4L with a number of different pulley combinations to maximize boost and power. Run with the stock blower/crank pulley combination (3.0/7.5-inches), the supercharged Lightning recorded 348 hp at the wheels and 439 lbs. ft. of torque. The Eaton M112 supercharger produced a maximum boost reading (at 5,000 rpm) of 9.3 psi. According to our data logging, the charge temperature exiting the blower measured 207 degrees. Using the ultra-efficient, factory air-to-water intercooler, the charge temp was reduced to a relatively chilly 85 degrees.
We eventually stepped boost up to a peak of 13.4 psi using a 3.0/9.0-inch pulley combo; the 5.4L produced a peak of 396 wheel hp (all testing measured on the DynoJet). Increasing the blower speed even further with a smaller blower pulley resulted in no extra peak power, just an increase in torque production lower in the rev range. We also noted an increase in vacuum present in the inlet system before the blower, a sure indication of a restriction. Replacing the factory air intake system and stepping up to a larger Accufab throttle body resulted in a final power reading of 415 wheel hp at 14.7 psi.
Having reached the effective limit of the Eaton supercharger, we installed the twin-screw upgrade from Kenne Bell. The twin-screw supercharger upgrade bolted directly in place of the M112 Eaton, using both the factory lower intake and intercooler. Kenne Bell also designed their supercharger upgrade to accept the stock inlet manifold, thus allowing use of all the factory throttle body, linkage, and air intake hardware.
Once installed (an easy swap), we started the test by running the Kenne Bell-supercharged 5.4L with the same 3.0/7.5-inch pulley combo run on the Eaton. So equipped, the Kenne Bell combo produced 403 hp, a gain of 55 hp over the 348 hp produced by the factory blower with the same pulley combo. The larger (more efficient) twin-screw blower increased the boost pressure from 9.3 psi to 13.2 psi. Knowing there was plenty left in the Kenne Bell blower, we stepped up the blower speed using the 9-inch crank pulley, which resulted in 449 hp. As before, data logging indicated vacuum present in the inlet system. Stepping up to the final combo, which included the revised inlet system and 2.57-inch blower pulley, resulted in 522 wheel hp (and more than 600 lb-ft) at just under 22 psi.