Non-production cylinder blocks
C5R: Developed for the factory-backed Corvette racing program, the C5R cylinder block has been manufactured in comparatively small quantities since 2000. They are manufactured with a unique aluminum alloy for greater strength and undergo a variety of specialized machining and inspection processes, including "hipping" to increase strength and X-raying that ensures against unacceptable porosity. A Siamese bore design with 4.117-inch finished bores enables 7.0L (427-cu-in) displacements. The C5R uses billet steel main caps with premium, 4340 fasteners. Racing-quality head studs are also included. All LS series heads will work with the C5R block, but maximum performance depends on maximum airflow.
LSX Bowtie Block (standard and tall-deck): Introduced in 2007, the LSX Bowtie Block is a durable and affordable cast iron casting that was designed to support extreme high-performance combinations, including provisions for six-bolts-per-cylinder head fastening. It has a Siamese bore design with 3.99-inch bores that must be finished to 4.00 inches - with a 4.25-inch recommended maximum bore. Maximum stroke can reach 4.25 inches, but rotating assembly interference on the cylinder must be taken into account for strokes greater than 4.125 inches; heavy metal is required for crankshaft balancing of larger-stroke combinations. Standard versions feature decks 0.020-inch taller than LS production blocks, with the tall-deck version manufactured with a 9.70-inch semi-finished deck height. The oiling system is a true priority-main system and all LS small-block heads work with the engine. Higher-airflow heads, such as LS7 and C5R, are recommended.
Crankshafts
Generally, LS crankshafts are similar in design, with identical 2.10-inch rod and 2.65-inch main journal sizes and a common rear main seal. All LS engines uses iron crankshafts except the LS7, LS9 and LSA; they used forged steel cranks (4.00-inch stroke on the LS7; 3.62-inch stroke on the LS9 and LSA).
The crankshaft sensing function of the distributorless ignition system depends on reading the toothed reluctor wheel on the crankshaft. Early LS engines mostly used 24-tooth wheels and upgraded a few years ago to 58-tooth (also known as 58X) wheels. When building an LS engine, it is imperative the correct reluctor wheel is used with the compatible crankshaft position sensor and ignition controller.
The crankshafts are mostly interchangeable, but the snouts on LS7 and LS9 crankshafts are approximately 1-inch longer to accommodate their two-stage oil pumps that work with the engines' dry-sump oiling systems. These forged crankshafts can be used on wet-sump engines by using a few specific components and/or modifications.
The easiest way to put a forged stroker crankshaft in your LS engine is using GM Performance Parts' new LSX crankshafts, which are available in four stroke sizes up to 4.125 inches. They feature the standard-length snout and can be used without modification on most engines. LS7 and LS9 crankshafts can be used, but require special components and/or modifications to their snouts to accommodate standard, wet-sump oiling systems.
Connecting Rods
LS connecting rods are very similar and interchangeable. Most are made of powdered metal, while the LS7 and LS9 rods are forged titanium. Rods lengths are similar, too, at 6.098-inch for 5.3L, 5.7L, 6.0L and 6.2L engines. The 4.8L engine uses 6.275-inch rods and the LS7 uses 6.067-inch rods. Since 2006, LS rods use bushed small ends. Also, LS6 rods bolts, P/N 11600158, offer a strength-enhancing upgrade to pre-2000 engines. Finally, because of the pistons' inner bracing, non-LS7 rods will not work with LS7 pistons; and the LS7 rods have a slightly different size than other LS rods, requiring a unique bearing, P/N 89017573.
Pistons
The LS9 is the only production LS engine with forged aluminum pistons; all the other use hypereutectic (cast) aluminum alloy pistons - varied mostly by diameter to accommodate various bore sizes. LS cast pistons shouldn't be used on applications greater than approximately 550 horsepower. Also, the LS7 piston's inner bracing requires the use of the matching LS7 connecting rod.
Cylinder Heads - Port Design Cylinder head interchangeability enables great parts mixing to build custom LS engine combinations, but the heads must be matched with intake manifolds that have compatible intake port configurations. The port sizes and shapes include:
Cathedral port - Introduced on the LS1 engine and used also on the LS6 and LS2, cathedral-port heads are named for the unique shape of the top of the intake port. Intake manifolds for LS1, LS2, LS6 and Vortec engines with cathedral-port heads are mostly interchangeable.
Rectangular port - LS7-style - The second LS intake runner design debuted on the Corvette Z06's LS7 engine. This rectangular design supports the straight-through airflow design of the heads. They feature 270cc intake ports and the ports and combustion chambers are CNC-ported from the factory. Use only with the LS7 intake manifold.
Rectangular port - L92 style - Similar to the LS7 design, but the ports are a little taller and a little narrower. They flow more than cathedral-port heads, but not as much as LS7 heads. In addition to the L92 6.2L engines, this port shape is also used on LS3 engines and some 6.0L truck engines, as well as the Corvette ZR1's LS9 and Cadillac CTS-V's LSA supercharged engines. Intake manifold bolt patterns are unique to this port design.