West finished off the sleeves with a honing plate, squared the decks, and align honed the saddles and cam bores. Since an aluminum block requires a tighter oil clearance than cast iron, the balanced crankshaft was installed with a bearing clearance of 0.002-inch. Though ARP studs sprang from the deck, neither block nor cylinder heads were prepared for O-rings. The 6.125-inch Lunati Pro Billet I-beam rods are 4340 steel forgings, weigh 630 grams, and were combined with ARP 7/16-inch 4340 fasteners. Fitting the 4.100-inch Lunati stroke to the stock 3.90-inch bore yields a displacement of 395ci. For this pocket assassin, the Lunati low-compression stroker kit also included pistons with a -30cc dish, wrapped with a Sealed Power moly 1.5mm top (0.028 end gap), ductile iron 1.5mm
Crankshaft and connecting rods were fitted with Clevite bearings. The crankshaft’s ECU target wheel, an LS-1 type 24xe, was welded in place (though not a common occurrence, it is possible that the press-fit OE wheel could come loose). The Lunati kit is carefully engineered to allow the proper piston-to-reluctor ring clearance. A short pin is fitted on the 4.1-inch stroke crank, allowing the piston boss to cleanly bypass the reluctor ring. West disassembled a new Melling HP G-rotor oil pump, smoothing and de-burring all the sharp edges. As it requires extremely close clearances to function correctly, the G-
A custom-phased Comp Cams camshaft, whose specs remain proprietary, is a hydraulic roller with 0.580-inch lift, and its 212/218 degrees (at 0.050-inch) duration suggests a great idle quality at 800 rpm. A Race Tec timing gear, with Timken thrust bearings and a dual roller timing chain replaced the stock single roller GM chain. To stand up to the increased valve spring loading, West also used Comp Cams roller lifters and custom titanium retainers to reduce valve weight. The Comp Cams shaft rocker kit (1.7:1) has the strength necessary to open the exhaust valves under the high cylinder pressure produced by the turbocharged engine. The CNC-ported LS6 GM cylinder heads (PN 88958665) make excellent power. The combustion chamber features an increase in CC’s on the sparkplug side, and the now-oversize 74 cc chambers (61.5 or 65cc are standard) yielded a compression ratio of 9.0:1 with the dished Lunati pistons. The heads are CNC-ported and hold 2.00/1.55 valves, dual springs, and titanium retainers. They were flow tested and ported some more. As such, the flow results surpassed 308cfm on the intakes and 255cfm on the exhaust at 0.600-inch valve lift. As an interesting aside, the LS7 CNC castings are capable of moving 348 and 219cfm, respectively. |
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