ATK Ford 351W 300 HP HP09M Stage 2 Mid-Dress LB Engine

ATK Ford 351W – Windsor Street Application

The ATK Ford 351W 300 HP HP09M Stage 2 Mid-Dress LB Engine resolves the performance restrictions common in aging factory 5.8L Windsor blocks. By providing a precision-machined Stage 2 foundation, this unit overcomes the oiling and compression inconsistencies found in standard high-mileage cores. This configuration utilizes superior cylinder sealing techniques, allowing the 351 Windsor architecture to deliver a dependable 300 HP while managing the thermal loads typical of classic muscle car street use.

Integrating this mid-dress long block package provides a distinct advantage by eliminating the variable shop hours of independent part sourcing. Adopting this HP09M assembly saves over 58 shop hours through the pre-installed intake and distributor system components. This dyno-ready foundation ensures 300 HP consistency, offering professional builders a dependable 5.8L solution that minimizes the threat of installation-related component fatigue during the initial startup phase.

ATK High Performance HP09M Ford 351W Specifications

• The reciprocating assembly features a 5.8L by 351 cubic inch displacement profile
• Peak performance reaches 300 HP output with high torque capacity
• Internal compression is set at Stage 2 ratios for thermal efficiency
• Rotating components consist of high-tensile materials to maintain stability
• Cylinder head architecture utilizes cast iron for superior structural rigidity
• The block foundation uses cast iron to prevent cylinder wall distortion
• Valvetrain configuration follows hydraulic roller standards to ensure timing control

Ford 351W Power & BMEP Characteristics

The 351 cubic inch stroke generates a torque peak far earlier than standard 302 engine builds. This modification enhances instantaneous throttle response sensitivity, providing immediate power for heavy-chassis Ford truck or Bronco swaps. At 300 HP, the BMEP remains stable under hydraulic roller control, preventing detonation during rapid acceleration events.

Material Integrity & Ford Windsor Durability

Durability is engineered through the combination of a high-rigidity iron block and matching cast iron heads. This hybrid construction eliminates thermal fatigue risks common in legacy Windsor configurations when subjected to high-load cycles. The external 28 oz. balancing process removes stress risers from the crankshaft, ensuring survival through extreme heat cycles where structural integrity is mandatory.

HP09M Drivetrain & Ford Windsor Integration

This engine bolts directly to Ford transmissions utilizing a 1-piece rear main seal and Windsor-specific bolt patterns. Because the assembly uses a 28 oz. external imbalance, builders must use the included harmonic balancer and flexplate. This prevents destructive torsional vibrations that could damage sensitive drivetrain bearings. The provided water pump and timing cover ensure the factory-correct belt drive alignment.

Ford 351W Street & Swap Versatility

This 351ci unit is a primary choice for Mustang restorations, Bronco conversions, and classic F-100 truck swaps. It maintains a safe compression safety margin, allowing for worry-free operation on standard 91 octane fuel. The hydraulic roller valvetrain ensures smooth idle quality and AFR stability, making 300 HP manageable in heavy traffic or during long-distance highway cruising.

Fitment & Ford 351W Installation Protocol

Builders must confirm chassis clearance for the provided Ford oil pan and the high-deck block height. The protocol requires verifying the fuel pump pressure to support the 300 HP peak output potential. Check accessory drive alignment against the provided water pump and timing cover. Professional priming of the lubrication system is mandatory before the first Windsor ignition.

Warranty & Support Compliance

ATK High Performance stands behind this 5.8L build with a limited 1-Year warranty against defects in workmanship. Claims require documented professional installation and complete engine warranty registration forms. US-based technical support provides guidance on startup and break-in protocols to safeguard this significant mechanical investment during the critical first 500 miles.

Final installation and chassis compatibility must be verified against manufacturer’s current technical bulletin and vehicle-specific measurements.