5 Lowering the fan switching temp may cause the fans to turn on frequently, as the coolant will still be fairly warm thanks to the stock thermostat. The Gen II small-blocks use a uniquely designed thermostat, and while replacements are readily available, all the ones we found at the local parts store were for the stock temperature. Fortunately, the aftermarket offers cooler T-stats for the LT1, so we sourced one from Jet and tried again. Lowering the coolant temp further should continue to boost power, and the next round of pulls confirmed this as we gained an additional 2 hp. We suspect that this change may normally be worth a little more, as our coolant was already fairly warm from previous tests.
6 Another area often compromised on late-model vehicles is the air cleaner and its ducting. Since auto manufacturers have to subject their vehicles to drive-by noise tests, most air cleaners are baffled to reduce intake "roar"--the sound your mom's station wagon used to make when you flipped the air cleaner lid over. The LT1 Caprice seemed strangled judging by the look of its stock air intake setup. The filter box itself is fed by a small, oval inlet that faces the back of the headlamps and the duct to the mass-airflow sensor (MAF) has a huge resonance chamber with offset inlet and outlet connections. Another resonance chamber is mounted atop the intake manifold, though it doesn't seem to obstruct airflow. We figured a more direct shot to the throttle body would have to help output at least a little.
7 As a trial experiment, we pulled the lid off of the filter box and faced it forward so it became the inlet to the intake tract. We stuck the stock paper filter element in it and made a pull, showing an instant gain of another 3 hp, and this was with the resonance baffle still in place. We were onto something.
8 We started scheming to create a high-flow air intake setup, with visions of drilled filter boxes and 3-inch exhaust tubing dancing in our heads. Of course, we also wanted to use a high-flow aftermarket filter, and that's when we learned that K&N actually offers a complete cold-air kit for the Caprice. Actually, this FIPK (Fuel Injection Performance Kit) was developed for the Impala SS, but the hardware is identical on the cop-spec Caprice, so we ordered it up. This kit includes a new filter box, which seals to the hood to keep out hot engine-bay air. It also uses a conical filter rather than the stock panel-type, and it even includes a tube to replace the resonance baffle.
9 Installation is relatively simple. The stock filter box is removed, which is a simple matter of a couple screws and a few snap-fit connections at the base. The K&N box then attaches to the same mounting points and includes a separate filter for the hose that feeds the engine's air injection pump, which was originally attached to the stock airbox. The filter and tube attach to the box, and the tube is then connected to the stock MAF. When it was all said and done, the K&N kit boosted power to 235 hp and 290 lb-ft of torque.