Cast-Iron LSX Block - Low Buck Brawler

New GM castings form the basis of the TSP/Precision Race Components head lineup, including these L92/LS3 ported units. PRC (essentially TSP's in-house cylinder-head shop) takes them through a full five-axis CNC program that results in outstanding flow numbers of 356 cfm on the intake and 235 cfm on the exhaust (measured at 0.650 lift). PRC sells the ported heads with factory 2.165-inch intake and 1.59-inch exhaust valves for a shockingly low $1,124.99 per set (PN 199-621).

The heads are placed in position over the dowels, and a set of optional ARP hex-head bolts (PN 46-134-3610) are lubricated and threaded into position. L92/LS3 heads have a total of 15 head bolts, with 10 larger bolts in the center and bottom and five at the top. Head bolts 1-10 are torqued to 75 ft-lb in a specific sequence that goes from the center outward, alternating sides. A second pass takes them to 85 ft-lb. The five head bolts on the surface closest to the intake valley are then torqued to 23 ft-lb, alternating side to side and working outward. For extreme forced-induction or nitrous use, TSP offers ARP's Pro-Series 12-point studs (PN 46-234-4317).

Once complete, the engine is rotated, a new O-ring seal is placed in the oil pump, and the pump's screen tube is pushed into position with the correct crank-bearing cap stud. The single 10mm bolt is torqued to 106 in-lb. The remaining crankshaft oil-deflector (aka windage tray) nut is then tightened to 18 ft-lb. After installing a new gasket in the oil pan, the pan is placed on the bottom of the block, and a total of 14 bolts are threaded into position. The pan-to-block and front-cover bolts are torqued to 18 ft-lb, while the pan-to-rear-cover bolts are set at 106 in-lb.

A GM LS2/LS7 valley-plate cover (PN 12570471) is used in place of the more common L72 version, which contains provisions for the active fuel-management (AFM) system used on other models. Note the oiling-provision block-off on the non-AFM plate. Included in the plate cover are new gaskets and 11 new bolts. Once the bolts are loosely tightened, the cover is torqued to 29 ft-lb.

The L92/LS3 heads require a specific rocker pedestal (GM PN 12600936) due to the offset intake rocker arms (GM PN 12569167) that are used. Although they're offset like the LS7 units, the L92 rockers use a 1:7:1 ratio and will not fit any other LS heads. After laying the rocker pedestals in place, a set of TSP hardened 7.4-inch, 0.080-wall chrome-moly pushrods (PN 25-7400) are slipped into position. The offset intake rockers and a new set of LS1/LS2 exhaust rockers are then torqued to 24 ft-lb. Note the TSP dual-spring kit (PN 199-SPKIT) which includes premium springs rated to 0.660-inch lift and comes complete with hardened seats, viton seals, and titanium retainers. Once both heads are complete, stock LS1 valve covers are installed and torqued to 106 in-lb.

Although an LS1 or LS2 timing cover will bolt on, a Quick Time Performance Quick Cam two-piece timing cover is utilized here to allow fast cam swaps in the dyno cell. The aircraft-aluminum cover comes with a new OEM crank seal and is designed so that the crank pulley doesn't have to be removed in order to swap cams.

Rather than using a stock balancer pulley, TSP installs an SFI-approved PowerBond Race Series 10 percent underdrive unit (PN 25-PBU1480-SS10). The balancer is placed over the crank hub, pressed on with an LS-specific tool, and torqued to spec. A Meziere LS-Series electric water pump (PN MEZWP) comes with a free-floating idler pulley, along with new gaskets and mounting bolts. After the bolts are snugged up, they're torqued first to 11 ft-lb, followed by a final pass to 22 ft-lb. Finally, a thermostat housing is installed.

Induction duties will be handled by a GM L76/L92 intake-manifold assembly (GM PN 12590123). This now-discontinued piece included fuel rails, 39-lb/hr injectors, and an LS2 90mm throttle body. (Although not offered as an assembly, GM recently released the LS3 intake [GM PN 12602477], whose throttle body, fuel rails, and injectors are all available individually.) The manifold assembly is installed and torqued to spec.

Finally, the long-block is placed on Sunset Racecraft's DTS engine dyno. In order to hook up an exhaust, TSP brought out a set of custom dyno headers manufactured by Kooks. These special-order units utilize 17/8-to-2-inch stepped primaries with a 3-inch collector. After bolting them on with new GM exhaust-manifold gaskets and stock bolts, a set of LS1 coil packs are mounted on the rocker covers. NGK TR6 spark plugs, MSD 8.5mm Superconductor wires, and a dipstick tube go on next, and the engine is ready for testing. Check back next month for all the numbers.