![]() If you look closely inside a skirted Dart block you’ll notice that the area underneath the pan rail is opened or scalloped to direct oil away from the crankshaft, again especially beneficial for long-stroke engines. Dart also offers a windage tray that is designed to work with the Dart splayed main caps. The Dart splayed cap design is intended to increase the common area between the cylinder cavities to reduce windage issues and maintain solid main webbing without communication windows. On the skirted blocks, these caps eliminate the need for the small, horizontal bolts used on production LS blocks. Moving to the bottom side of the block, both the iron and aluminum blocks use steel main caps with the outer bolts splayed on the center three caps to increase strength. Opting for the LS Next without the skirt replaces the iron skirt with aluminum spacers that allow the use of a typical LS configuration oil pan. Thicker deck surfaces are also an inherent advantage measuring a stable 0.625-inch. An LSNext block will offer a minimum of 0.275-inch wall thickness at a 4.185-inch bore diameter. Aluminum blocks can go as large as 4.165in. ![]() The LS Next iron, non-skirted race blocks can be bored as large as 4.200in while the cast-iron SHP blocks have a max bore of 4.185in. Speaking of bore size, LSNext aluminum and cast iron blocks start at 4.00in and 4.125in versions, and can be bored as large as 4.185. Dart’s longer sleeve length prevents this issue yet there is still plenty of clearance for up to a 4.100-inch stroke on any of the LS Next blocks. This forces the piston to rock over center which can damage the piston skirt. A long stroke LS package will tend to pull the lower half of the piston skirt completely out of the bore at bottom dead center (BDC). When adding stroke, this increases the distance the piston travels. If big power is anticipated, Dart offers an upgrade to ½-inch (0.500-inch) studs. Which main cap fasteners would you prefer? Stock LS engines use 10mm (0.393-inch) fasteners while the Dart block uses 7/16-inch (0.4375-inch) fasteners. The goal with the non-skirted block was to create a pan rail position similar to the original small-block Chevy. This offers an immediate 100-pound weight savings.ĭart was the first to eliminate the deep skirt with the iron LS Next block in an effort to minimize windage issues that has shown to be a significant impediment to making high rpm horsepower. A typical iron non-skirted LS Next block will weigh in at 227 pounds while an aluminum version of that non-skirted block will come in at between 115 and 127 depending upon bore size. The main advantage to aluminum blocks is their reduced weight. Enhancing these standard cast block offerings are multiple custom options such as cam upgrades, lifter bore resizing, stroke clearance, piston oil squirters, 1/2in main studs and many more. At the top rung are custom billet aluminum blocks that we will cover in more detail in a separate story. All Dart aluminum blocks use ductile iron sleeves and extra thick cylinder walls. Moving into alloy materials, the LS Next aluminum blocks are available in either skirted or non-skirted configurations. This production iron LS block reveals how the area near the main webs is very restrictive and how this contributes to windage problems especially with longer stroke engines. This is the ultimate cast-iron LS Next block for the highest horsepower applications. Additionally, the LS Next iron non-skirted race block is capable of receiving the LS Next 2 upgrade which incorporates larger main caps and 1/2in main studs. This block also features 220 BHN material and will accept up to 4.200-inch maximum bore diameter. Up from that is the LSN Next iron non-skirted race block which uses a conventional 4-bolt, splayed cap in the center three and oil pan rail position that allows kick-out oil pans where chassis clearance is available. Standard LS main diameter is 2.560-inch.Refers to a conventional pan rail that eliminates the LS skirted configuration using pan rail spacers to locate an LS pan bolt pattern.The LS Next Pro also upgrades to ARP 7/16in main studs from bolts. This harder cast iron also increases the block’s tensile strength from 30,000 to 38,000 psi. By using a superior grade material and employing a different heat treat technique, Dart offers the LS Next SHP at 220 BHN. Typical grey cast iron tests between 192 BHN. ![]() This number relates to the Brinell hardness (BH) rating. Next up is the LS Next SHP Pro iron block that is cast using a superior strength 220 BHN iron material. Production LS blocks feed the hydraulic lifters first, which isn’t a good idea in a performance or race engine. ![]() This shows the location of the priority main gallery that feeds oil directly down to the main webs to feed the crank rods. ![]()
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