I was looking for info on the LS4 and stumbled apon this. Never really knew what the LS4 was all about until now.

Generation IV 5.3L LS4 V8 Overview

The 5.3L LS4 shares the basic architecture of the 6.0L LS2. This includes an all aluminum block, six-bolt main bearing caps, deep-skirt cylinders, and a structural oil pan. It has the 243 casting LS6 heads with LS1 valve springs, which are good for 6200-6300rpm.

Engineers had to mount this engine sideways so some changes were made. The crankshaft is shortened by 13 mm overall; 3 mm at the flywheel and 10 mm at the accessory drive. This was done to accommodate a more compact accessory drive. Instead of a 2 belt system there is only 1 long serpentine belt, even with this to save space there is only about 2 inches between the crankshaft pulley and the passenger side wheel well. The water pump is mounted off center with elongated passages to connect to the block (see picture). Also a rear facing intake manifold was designed. To ensure proper oiling during high-g cornering the oil pan has special baffles built in. Since Displacement on Demand uses oil for activation an oil pump with 31% more flow than previous LS2 type oil pumps is used.

Displacement: 325ci (5328cc)
Compression Ratio: 10:1 (premium fuel is recommended)
Bore x Stroke: 3.78" x 3.622" (96mm x 92mm)
Firing Order: 1-8-7-2-6-5-4-3
Horsepower: 303 hp @ 5600 rpm
Torque: 323 lb-ft @ 4400 rpm
Fuel Cut-off: 6100 rpm

5.3L LS4 V8