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Home Engines Short Block Engines ATK High Performance Chevy LS 408 Short Blocks SP40-G4-B
ATK High Performance Chevy LS 408 Short Blocks SP40-G4
ATK High Performance Chevy LS 408 Short Blocks SP40-G4 $2,539.00
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ATK High Performance Chevy LS 408 Short Blocks SP40-G4-B

$2,968.00

Short Block, Chevrolet LS Gen IV 408 Stroker, Internally Balanced, Nitrous/Boost, 24 Tooth Reluctor, +29cc Dish Pistons, Each

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Category: Short Block Engines
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Description

Overview

Brand: ATK High Performance Engines
Manufacturer’s Part Number: SP40-G4-B
Part Type: Short Block Engines
Product Line: ATK High Performance Chevy LS 408 Short Blocks
Summit Racing Part Number: HPE-SP40-G4-B
UPC: 653517518348
Crate Engine Family: Chevy LS
Actual Engine Displacement: 6.7L/408
Rear Main Seal Style: 1-piece
Crankshaft Material: Forged 4340 steel
Piston Material: Forged aluminum
Short Block Piston Style: Dish
Connecting Rod Material: Forged 4340 steel
Connecting Rod Beam Style: H-beam
Engine Block Material: Cast iron
Main Bolt Style: 6-bolt
Main Journal Type: Chevy LS
Deck Height (in.): 9.240 in.
Engine Balance: Internal
Oil Pan Included: No
Timing Cover Included: No
Harmonic Balancer Included: No
Flexplate Included: No
Flywheel Included: No
Assembled: Yes
Remanufactured: Yes
Quantity: Sold individually.
Notes: GM 6.0L Gen IV block with 4.030 in. bore and 4.000 in. stroke, -29cc dished pistons and 24 tooth reluctor. Boost/nitrous ready with Manley forged 6.125 in. connecting rods, upgraded ARP main studs, ARP 2000 rod bolts, and Total Seal CS AP ring package with steel rings.

ATK High Performance Chevy LS 408 Short Blocks

These ATK High Performance Chevy LS 408 short blocks are made to handle some serious power. The foundation of any high performance engine is a rock-solid short block, so ATK designed and developed these to be just that. They feature a fully forged, balanced, and blueprinted rotating assembly that is available in a variety of configurations to fit naturally aspirated, nitrous, and forced induction builds, as well as those with 24 and 58-tooth cranks.

These ATK High Performance Chevy LS 408 short blocks include the following:

* GM LS Iron blocks
* Aligned and hone main bores
* Manley 4340 forged crankshaft
* 4.00 in. stroke
* Manley 4340 H-beam connecting rods
* Manley forged pistons

Applications

Make: CHEVROLET
Engine Type: V8
Engine Size: 6.7L/408
Engine Family: Chevy small block Gen III/IV (LS-based engines)
Application Notes: GM 6.0L Gen IV block with 4.030 in. bore and 4.000 in. stroke, -29cc dished pistons and 24 tooth reluctor. Boost/nitrous ready with Manley forged 6.125 in. connecting rods, upgraded ARP main studs, ARP 2000 rod bolts and Total Seal CS AP ring package with steel rings.
Shipping & Delivery
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Effective Date: August 9, 2025

At X Factors Motorsports, we are committed to delivering your order quickly, securely, and affordably.


1. Processing Time

  • Orders are typically processed within 1–2 business days after payment is confirmed.

  • Orders placed on weekends or holidays will be processed on the next business day.


2. Delivery Times

  • Domestic Shipping (United States): Delivery takes 5–7 business days from the date of shipment.

  • International Shipping: Delivery times vary by destination and may take 7–21 business days depending on customs processing and local delivery services.


3. Shipping Rates

  • United States: Free standard shipping on all orders.

  • International: Shipping costs are calculated at checkout based on the delivery address, package weight, and destination country.


4. Carriers Used

We ship orders using trusted carriers such as UPS, FedEx, USPS, and DHL to ensure reliable delivery. Tracking numbers are provided for all shipments.

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    At X Factors Motorsports, we specialize in high-performance engines, outboards, and premium automotive equipment. With expert support, fast shipping, and trusted brands, we help builders, racers, and enthusiasts power their passion — one project at a time.

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