The Gen IV 5.3L V-8 (LS4) debuted in the 2005 Pontiac Grand Prix GXP, which was significant on several levels: It was the first time a small-block V-8 engine was offered in a front-drive car, and the first V-8 since the rear-drive platform of 1987 to come in a Grand Prix. The 5.3L was engineered specifically for front-drive layouts, and produces 303-horsepower and 323 lb.-ft. of torque. The Gen IV 5.3L uses Displacement On Demand (DOD) technology, which deactivates four cylinders under low-load conditions to increase fuel economy up to 12 percent.
The LS4 uses an aluminum block, and shares a common architecture with the 6.0L V-8 available in the Chevrolet Corvette. It features include deep-skirt cylinders, six-bolt cross-bolted main bearing caps, a structural oil pan, and other strength and weight refinements. The 5.3L, however, was designed to mount transversely, versus the longitudinal positions of the 6.0L applications. The crankshaft was shortened 13 mm – 3 mm at the flywheel end and 10 mm at the accessory drive end – to reduce the length of the engine compared to the 6.0L. All accessories are driven by a single serpentine belt to save space. The water pump is mounted remotely and an elongated pump manifold connects it to the coolant passages. A more compact hydraulic belt tensioner is used instead of the rotary tensioner found on the 6.0L. Revised oil pan baffles, or windage trays, were incorporated into the 5.3L to ensure that oil continues to be available in the sump even during high-cornering loads for the sideways-mounted engine.
The 5.3L V-8 delivers strong performance – 90 percent of torque is available between 1500 rpm and 5200 rpm – and surprising economy.
The following pages document the progress of installing an LS4 into a Fiero. The engine for this swap was purchased as a complete package including the transmission, all accessories, wiring harness, PCM, TCM, etc.. It came from a 2006 Chevy Impala with 7 miles on the odometer. It's being swapped into an '88 Fiero GT. Some of the parts developed for this swap will be available from Fiero Addiction.