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These RHS LS bare race blocks are designed to meet the needs of today's high performance engine builders and racing enthusiasts. These blocks are available in standard and tall deck height combinations and are engineered for maximum clearance around a 4.600 in. stroke crankshaft. With their unique design, RHS engineers were able to minimize windage in the rotating assembly, leading to superior engine lubrication at higher rpm. To make them friendly for existing race applications, these blocks contain both factory and motor plate race mounts for Gen I, II, III, and IV engines. RHS LS bare race blocks each receive a CT scan to ensure maximum performance and consistency.

Standard features include:
- Designed from aircraft-quality A357-T6 aluminum
- Siamese cast bore walls (4.125 in. or 4.165 in. diameter) with press-in cast iron sleeves
- Machined with 55mm cam bearing journal
- Available in standard (9.240 in.) and tall (9.750 in.) deck heights with beefy deck thicknesses (.500 in. standard/.750 in. tall deck); standard (5.87 in.) and tall (6.38 in.) deck cylinder sleeves are available
- 6 head bolt design with full water jacket around the cylinders' walls; large windows in the valley allow access to an inboard 6th head bolt
- Block design includes large front and rear AN-12 side feeds for serious dry sump setups
- Material for oversized lifters with lifter bosses that are designed to clear tie bar style lifters

Main Journal Type: LS mains

Engine Block Style: Aftermarket/OEM tall deck

Deck Height (in): 9.240 in.

Cylinder Bore as Shipped: 4.115 in.

Cylinder Bore Diameter: 4.125 in.

Maximum Bore Diameter: 4.165 in.

Engine Block Material: A-357 Aluminum

Engine Block Weight (lbs): 119 lbs.

Main Bolt Style: 6-bolt

Main Caps Included: Yes

Main Cap Material: Steel

Main Cap Fasteners Included: Yes

Main Bearings Included: No

Rear Main Seal Style: 1-piece

Finished Cylinder Bores: No

Raised Cam Location: Yes

Cam Bearings Included: No

Freeze Plugs Included: Yes

Notes: Needs finished honed.

In Store Pickup: Anaheim, CA, USA

Return Policy

RHS Standard Deck Block 54903U

Quantity