The last time you saw our project '78 Malibu, Magnaflow Performance had just outfitted the family sedan with a free-flowing exhaust, and we were sorting out the last minor details on the LT1 conversion (see "Buttoning Up the 'Bu," Oct. '02). With most of the bugs worked out of the swap, we're ready to do what we love best--bolt on horsepower!
To see how well a late-model LT1 small-block responds to typical aftermarket bolt-on goodies, we ordered a set of JBA Header's Power Cables to replace the worn-out factory spark-plug wires, opened up the air-inlet tract with a High Flow Induction System from Moroso, added a larger mass-airflow meter from Granatelli Motor Sports, and installed a BBK Performance 58mm throttle-body assembly.
Our baseline dyno flogging at Morgan Motorsports' chassis dyno in Reseda, California, generated impressive numbers out of this salvaged LT1, with 259 hp and 291 lb-ft of torque. This was down somewhat from our last session, which produced 270 hp and 299 lb-ft of torque, but we think a change in weather from our last test has a lot to do with it (these are uncorrected numbers). Although the baseline power was down, it didn't affect the comparison numbers for the bolt-ons. We tested each component one at a time and were pleased to find that the fuel-injected LT1 graciously accepted the additional airflow. The new parts combined for a 20hp gain at the rear wheels, and drivability and throttle response improved as well. Read on for the details.
Replacing spark plugs and wires can be a painstaking process on typical late-model F-bodies. Fortunately, our LT1 rests comfortably within the confines of a luxurious '78 Chevy Malibu engine compartment, and its ample room makes the job easy. We ripped out the old factory wires and replaced them with a set of new JBA Headers power cables, which are '94 to '97 application-specific and feature heavy-duty silicone sleeves for added thermal protection and extra-thick plug boots to help repel external contaminants. The plug-wire change freed up an additional 5 hp and 4 lb-ft of torque on the dyno! Of course, wires aren't really a power adder, but it shows you the performance gains basic maintenance can make. |  |
Running an engine without an air filter isn't something you want to do for everyday street use, so a high-flow induction system with a free-flowing filter element that draws cold air from outside the engine bay is the best option. On the dyno, our LT1 ran better with Moroso's High Flow Induction System (middle) than without a filter (top). | 
It's as if the LT1 was designed with our G-body platform in mind. Although our Moroso High Flow Induction System was intended for a '93-or-later Camaro and Firebird LT1, we used a Sawzall to cut a hole through the inner plastic wheelwell and massaged the mounting plate into place. Once the plate was mounted, we drilled two 3⁄16-inch holes to secure the system and clamped the inlet air duct with the supplied hardware. Pretty trick. |
Underneath, the Moroso filter draws in cold air, yet sits high enough so that we don't have to be concerned with rain or water puddles. The filter is washable, reusable, and doesn't have to be serviced until after 50,000 miles (more often in areas with heavy dust conditions). | 
Swapping over the new meter took only a few moments and proved to be a true "bolt-on," requiring only the removal of two hose clamps and disconnecting the sensor's wiring harness. |
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Upstream of the inlet system, we replaced the factory mass-airflow sensor with a larger Granatelli Motor Sports unit. The larger unit offers 47 percent greater airflow over the stocker MAF sensor and is precalibrated to deliver flawless driveability. Granatelli Motor Sports also offers custom calibrations to enrich the fuel curve for higher horsepower nitrous or blower applications. |
Topping off our induction system is a massive BBK Performance 58mm throttle body that clearly dwarfs its 48mm factory counterpart. We skipped over the 52mm upgrade since the larger throttle body wouldn't be detrimental to performance; the mass-airflow meter will correctly meter the air/fuel ratio for the incoming air. The bigger throttle body will allow for future upgrades without it having to be replaced twice. | 
To swap the throttle body, disconnect the main inlet hose, all the vacuum lines, electrical connectors, and the throttle control cable. Remove the four mounting bolts, scrape the gasket material off the manifold, and swap over the factory throttle position sensor onto the new BBK throttle body. Installation shouldn't take more than 20 minutes. |
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