The Texas Speed 427ci Resleeved Gen IV Aluminum Short Block starts with a new GM Gen IV aluminum LS3 block fitted with heavy-duty Power Bore dry sleeves to reach a 4.125" bore, then adds a 4.000" stroke crankshaft, forged pistons and connecting rods chosen at ordering. Texas Speed machines and assembles each short block in house, producing a 427 cubic inch foundation for naturally aspirated, nitrous, supercharged or turbocharged engines.
Crankshaft options include the Texas Speed forged 4340 crank in 6-bolt or LSA-specific 8-bolt form, Callies Compstar wet sump and LS7 dry sump cranks, Callies Ultra billet cranks in 24x or 58x and a Bryant Racing billet crank. Pistons are a Texas Speed exclusive Wiseco 4.125" -4cc flat top, a CP-Carrillo -4cc flat top or a CP -20cc dish, and rods range from Texas Speed Super H-beam and I-beam rods to Callies and BoostLine rods. Oil and coolant plugs are installed and 12 quarts of break-in oil are included. An ARP main stud kit and Texas Speed 1/2" head stud kit are optional, and short blocks ship by truck freight with the shipping cradle and crate included.
Specifications
- Displacement: 427 cubic inches
- Block: New GM Gen IV aluminum LS3 block (GM 12729604) with Power Bore heavy-duty dry sleeves
- Bore: 4.125"
- Stroke: 4.000"
- Crankshaft: Selected at ordering (Texas Speed forged 4340 6-bolt or LSA-specific 8-bolt; Callies Compstar 8-counterweight wet sump or LS7 long-snout dry sump; Callies Ultra billet 24x or 58x; Bryant Racing billet LS1 center counterweight)
- Connecting rods: Selected at ordering (TSP Super H-beam, Super I-beam or billet Super I-beam; Callies Compstar, Compstar Xtreme or Ultra H-beam; Callies Ultra Enforcer I-beam; BoostLine 3-pocket)
- Pistons: Selected at ordering (Wiseco TSP exclusive 4.125" -4cc flat top 1.100" CH; CP-Carrillo 4.125" -4cc flat top; CP 4.125" -20cc dish)
- Reluctor: 24x or 58x, selected at ordering
- Main fasteners: GM bolts standard; ARP main stud kit optional
- Head studs: Texas Speed 1/2" 12-point head stud kit for standard 2004+ blocks optional
- Also included: Oil and coolant plugs installed, 12 quarts of break-in oil, shipping cradle and crate
- Applications per Texas Speed: Naturally aspirated, nitrous, supercharged or turbocharged
- Compression ratio: Varies with piston, chamber volume, head gasket and deck height
Kit Includes
- New GM Gen IV aluminum LS3 block (GM-12729604)
- Power Bore heavy-duty dry sleeves, qty 8 (TSP-PB-4070GEN4)
- Crankshaft, 4.000" stroke (selected at ordering)
- Connecting rods, 6.125", set of 8 (selected at ordering)
- Forged piston set, 4.125" bore, with wrist pins and rings (selected at ordering)
- Reluctor wheel, 24x or 58x (selected at ordering)
- Oil and coolant plugs, installed
- Royal Purple break-in oil, 12 quarts (RYP-11487)
- Engine shipping cradle (TSP-Cradle) and crate (TSP-SDCrateSB)
Ordering Options
Seven selections are made when ordering: crankshaft, connecting rods, piston set, reluctor wheel (58x or 24x), main stud kit (ARP or GM bolts), optional Texas Speed 1/2" head stud kit and the wrist pin upgrade choice (HD tool steel pins for Wiseco, .230" wall pins for CP, or none). Texas Speed also offers an LS1 conversion package with LS2 timing cover, valley cover, lifter trays, 1x timing set and harness extensions; ask before ordering.
Note: Verify the 24x or 58x reluctor selection is compatible with the vehicle's engine management, and verify piston volume and final compression ratio against the cylinder heads, chamber volume, head gasket thickness and deck height.
Note: Texas Speed lists the 4.000" stroke as its preferred maximum stroke for high-horsepower power-adder applications. Proper engine break-in is required to establish ring seal.
Note: All short blocks ship via truck freight. Final freight pricing is provided after the order is placed. Additional vehicle-specific components, tuning and supporting hardware may be required.
FAQ
What block does the Texas Speed 427 resleeved Gen IV short block use?
A new GM Gen IV aluminum LS3 block, part 12729604, fitted with eight Power Bore heavy-duty dry sleeves to produce the 4.125" bore needed for 427 cubic inches with the 4.000" stroke crankshaft.
Can this short block be used with a power adder?
Yes. Texas Speed lists naturally aspirated, nitrous, supercharged and turbocharged applications. The CP -20cc dish piston lowers compression for boost, and the 4.000" stroke is Texas Speed's preferred maximum for high-horsepower power-adder builds.
Does the 427 short block come with 24x or 58x?
Either. The reluctor wheel is selected at ordering as 24x or 58x, so the short block can match a Gen III 24x ECM or a Gen IV 58x ECM without a signal converter.
What is included with the short block besides the block and rotating assembly?
Oil and coolant plugs come installed, 12 quarts of break-in oil are included, and the engine ships on a cradle in a crate by truck freight. Cylinder heads, camshaft, timing set, oil pump and covers are not included.
Can I use this short block in an LS1 car?
Texas Speed offers an LS1 conversion package for this short block that includes an LS2 timing cover, valley cover, lifter trays, a 1x timing set and harness extensions. Contact BPS before ordering to add it.
How is final compression ratio determined?
It varies with the piston volume selected, the cylinder head combustion chamber volume, head gasket thickness and deck height. Texas Speed advises verifying the combination before ordering.
