The LS4 is a smaller 5.3 L (5,328 cc/325.1 cu in) version of the Generation IV block. Though it has the same displacement as the Vortec 5300 LH6, it differs in that it has an aluminum block rather than an iron one and it uses the same cylinder head as the Generation III LS6 engine.

This engine is adapted for transverse front-wheel drive applications. According to GM, "The crankshaft is 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 with an elongated pump manifold that connects it to the coolant passages. Revised oil pan baffles, or windage trays, are incorporated into the LS4 to ensure that the oil sump stays loaded during high-g cornering." [8] Active Fuel Managemment is also used. Output of this version is 303 hp (226 kW)/300 hp on LaCrosse Super and 323 ft·lbf (438 N·m).

Applications:

* 2006-2009 Chevrolet Impala SS
* 2006-2007 Chevrolet Monte Carlo SS
* 2005-2008 Pontiac Grand Prix GXP
* 2008 Buick LaCrosse Super