RHS 54901 LS Aluminum Race Block, 9.750 Tall Deck - 4.125 Bore
LS7 Chevy LS V8, 4.125" Bore Size, LS mains Main Journal Style, 1-piece Rear Main Seal Style
- This item ships directly from the manufacturer. It may take an additional 10 business days for Racing Head Service to ship this item.
- This item ships via Ground Shipping only. Expedited and Air shipping options are not available.
- Tall Deck Height (9.750)
- Finish Honed & Ready For Assembly
- 6.38" Cylinder Sleeve Length
- 4.125" Bore
Engineers at RHS have designed a high performance aluminum engine block for GM LS applications to meet the needs of race and street performance engine builders alike. To go beyond the limitations of other existing LS blocks, the new RHS LS Race Block is available in both standard deck and tall deck height configurations. Additionally, this innovative aluminum block features a raised cam centerline and outboard priority main oiling to allow rod clearance for a 4.600” stroke and to minimize windage in the crankcase. And for quality control assurance, RHS conducts a CT scan (similar to a medical CAT scan) on each block to ensure maximum casting precision and consistency. When you combine unmatched finishing quality with added clearance for increased stroke applications, precision computeraided design and extra surface material to allow custom machining, you get the new benchmark for LS horsepower, torque and durability.
- Designed from heavy-duty A357-T6 aluminum material
4.125”-4.165” siamese cast bore walls w/ press-in spun cast iron liner
Available in standard (9.240”) & tall (9.750”) deck heights w/ beefy .750” deck thickness
Both standard deck (5.67”/5.87”- same as LS7) & tall deck (5.94”/6.38”) cylinder liner lengths available
“Long arm friendly” – Accommodations for up to 4.6” stroke w/ standard rod pin diameters (2.100”) & oversized 60mm camshaft
Raised cam centerline (.388”/9.86mm) to allow larger stroke; 2 extra links in the timing chain – Timing sets available from COMP
Main cap surface area maximized at mating surface & large fillets from cap to cross bolts for added strength
Designed for clearance – side oil galley moved outboard & engineered rod clearance come standard
Significantly increased windage passage area under bores & around caps over LS7/LSX engines
6 head bolt design w/ full water jacket around the cylinders (based on LS7 design)
Bay-to-bay breathing improved w/ increased side window area versus LSX & LS7
Extra large windows in valley for access to inboard “6th” head bolt
Extra long liners for standard (5.87”) & tall (6.38”) decks
VALVE TRAIN CAPABILITIES
Provisions for Gen III & Gen IV cam & knock sensors & valley covers
Cam tunnel will accommodate stock through oversized 60mm roller bearing cams (includes cast-in lock screw pads)
.842” lifters standard with material available for oversized lifter access (accepts 1.060” bushing for keyed lifters)
In the standard deck, maximum pushrod angularity = Less than 2 degrees
Includes Ampco 45 cam thrust plate and aluminum rear cover
Lifter bosses designed to clear tie bar lifter
Priority main oiling, galley moved outboard for long stroke clearance
Oil filter feed galley GM “dog bone” replaced with proprietary no restriction threaded plugs
Dry sump friendly with provisions for more serious dry sump setups; includes big front & rear AN-12 side feeds
Includes provision for piston oil squirters, cast-in & machined
Rolled threads on all threaded holes for added strength
Gen III/Gen IV compliant with race mounts for Gen I, Gen II, Gen III & Gen IV engines
ARP main stud kit standard with enough material in castings to accommodate up to a ½” fastener
Chilled main bearing bulkheads for added strength
Optimized billet main caps & improved windage
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RHS 54900U LS Aluminum Race Block, 9.750 Tall Deck - 4.160 Bore
RHS 54903U LS Aluminum Race Block, 9.250 Standard Deck - 4.120 Bore
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