The first step to achieving a more powerful behemoth was to go to NOS (Nitrous Oxide Systems) in Costa Mesa, California, for a NOS EFI nitrous oxide kit. The NOS system is engineered with a failsafe mechanism utilizing dual nitrous solenoids that only allow full nitrous pressure when the OE fuel pressure "ramps up" to its maximum. Once armed, a throttle position switch activates the system when the linkage nears full throttle. Realizing this was a heavy car, it was decided to add a second 10-pound bottle in the trunk so there would be plenty of laughing gas on board for several sprints. NOS Bottle Pressure Gauges were also utilized in order to monitor the nitrous pressure in each bottle. To further ensure that the system would be at its optimum, a pair of NOS Electric Bottle Heaters along with a pair of NOS Bottle Blankets was also added.
During test launches with the nitrous-tweaked OE chassis, it was immediately obvious that the car required suspension work before continuing with the engine upgrades. The tail of the big boat would track off-center as the factory suspension links flexed. Hotchkis Performance upper and lower boxed trailing arms were installed on the rear axle to keep it in line. Although the stock handling on the road racing track proved impressive for such a large ride, its suspension height was designed for "hopping curbs" while pursuing the criminal element. H & R Special Springs replaced the OE coils, lowering this police package by roughly 3 inches while properly leveling the car on all four corners. Normally, an Impala SS would be lowered by only 2 inches, but this "cop edition" sat high. Tokico HP high-pressure, twin-tube gas shocks were installed on each corner. Hellwig Suspension Products "Sport Tech" anti-sway bars replaced the front and rear factory items, increasing the bar diameter enough to improve the roll stiffness and tame this heavy chassis. All of the suspension components, as well as the second nitrous bottle, were installed at Michelangelo Motor Werkes in Irvine, California.
During the baseline testing, the 4,500-pound Caprice performed reasonably well during the braking tests. However, once the braking system was subjected to repeated use on the road course, the weight, along with the unventilated rotors, was apparent. While entering Holtville's Turn 5 during the third lap, which required heavy braking from 100 mph, the pads failed. The car used the entire turn, including some agricultural driving, in order to keep the shiny side facing the sun. After that thrill ride, we contacted Power Performance Group in Chatsworth, California, which specializes in brake system upgrades. They recommended a set of Power Slot Police Package Brake Rotors. During the installation, the owner of the Caprice elected to switch to Raybestos carbon-metallic brake pads in order to further help the braking performance. All of these improvements in suspension and braking will only work to the limitations of the rubber on the car. The owner loved the look of the factory 17-inch Impala SS wheels and felt that the wheel diameter would best suit his driving, but he also desired a larger contact patch than what is available on the stock Impala. An extensive search revealed that it is difficult to locate a proper wheel fitment for these cars because they feature a 5x5 bolt circle, similar to that found on late-model GM trucks. Unless you wish to install Gumbo Monster Mudders, or go to the expense of custom three-piece wheels, your options are limited. Group A Autotrend in Phoenix, distributor for Australian made ROH Wheels, had a solution-their one-piece ZR6 cast aluminum wheels, which feature similar styling to the factory Impala SS, but feature a 17 X 9-inch size in the correct offset to allow for massive 285-series rubber (the stock Impala is 255 series). Pirelli manufactures the P-Zero performance radial tire in a 285/40ZR17 size, fitting perfectly on this chassis. Its special tread design is unidirectional for optimum handling in both wet and dry, and delivers good wear characteristics for their level of adhesion. In fact, the Pirellis showed less wear during the abusive track testing than the harder, stock 225/70-15 police car tires.