Description

The HKS COMPLETE ENGINE VR38DETT 4.3L STEP3 provides a sophisticated, street-focused performance solution. It is designed to deliver significantly enhanced low-speed torque while ensuring long-term reliability. Additionally, it offers refined drivability.

As the entry point in HKS’s complete engine hierarchy, this powerplant builds upon the proven 4.3L displacement platform with targeted durability enhancements. Specifically, it features strengthened main bearing caps and advanced bearing technology. These enhancements substantially improve bearing life under sustained street use conditions.

Engineered explicitly for enthusiastic street driving rather than extreme competition, this engine prioritizes urban riding comfort, accessible power delivery, and extended service life. It creates an ideal foundation for owners seeking substantial performance gains. This is without compromising daily usability or long-term reliability.

Product Highlights

🏙️ Street-Optimized Performance & Drivability Enhancement
Engineered specifically for street applications, this engine dramatically increases low-speed torque characteristics. Consequently, it improves acceleration response in urban environments while maintaining refined drivability for daily use. The torque target of up to 1,000 N·m represents a substantial increase over factory capabilities. However, it remains within parameters suitable for street-focused driving and moderate performance upgrades.

🔧 Durability-Focused Design for Long-Term Reliability
Strengthened main bearing caps and increased thread size on main stud bolts directly address longevity concerns. Therefore, they significantly extend bearing life and maintain structural integrity under sustained loads of spirited street driving. This durability-first approach ensures the engine remains in optimal condition across extended ownership periods. It does this without prioritizing peak performance at the expense of service life.

🎯 Targeted Enhancements for Street-Specific Requirements
Unlike competition-focused variants, the STEP3 incorporates enhancements specifically beneficial for street environments. For example, the molybdenum-coated pistons prevent initial galling and reduce friction during varied driving conditions. Meanwhile, the VR43-specific crank damper minimizes torsional vibration for smoother operation across diverse RPM ranges.

🔄 Balanced Performance Profile for Accessible Enhancement
By increasing displacement to 4,255cc while maintaining street-appropriate compression and RPM limits, this engine delivers substantial performance gains without requiring extreme supporting modifications. Accordingly, it provides an accessible yet transformative upgrade path. This is for owners seeking meaningful improvement within realistic street usage parameters.

Technical Specifications

Product Name: COMPLETE ENGINE VR38DETT 4.3L STEP3

Primary Application Focus: Street use with enhanced performance characteristics

Performance & Dimensional Parameters:

• Expected Torque Capacity: Up to 1,000 N·m (street-optimized application)

• Displacement: 4,255cc (12% increase over factory 3,799cc)

• Bore: 95.5mm (maintaining factory diameter for compatibility)

• Stroke: 99.0mm (12% increase over factory 88.4mm)

• Compression Ratio: 8.6:1 with 0.8mm metal head gasket

• Allowable RPM: 7,400 rpm (enhanced 400 rpm over factory limit)

Critical Component Specifications:

Block & Bottom End Enhancements:

• Strengthening: Increased main bearing screw size with enlarged and countersunk ladder cap holes

• Precision Machining: Line boring of journal holes ensures roundness under increased axial forces

• Fastening System: HKS M12 stud bolts (625+) with appropriate relief of crank interference

• Bearings: ACL main bearings and genuine connecting rod bearings with WPC treatment

Rotating Assembly:

• Crankshaft: HKS machined unit with fillet WPC reinforcement

• Pistons: HKS machined components with molybdenum coating for reduced friction

• Connecting Rods: HKS H-cross section design

• Damper: VR43-specific crank damper co-developed with ATI

Cylinder Head & Valvetrain:

• Camshafts: HKS high-opening design (IN: 270°/11mm, EX: 278°/11mm)

• Valve Springs: HKS reinforced products with sheet-lapped valves

• Sealing: HKS metal head gasket (t=0.8) with ARP reinforced stud bolts

• Spark Plugs: HKS M50HL specification

Finishing & Presentation:

• Covers: Baked paint finish for durability and aesthetic presentation

• Assembly: Complete engine delivered ready for installation

Recommended Lubrication: HKS Racing Pro 10W-50 engine oil

Performance & Application Philosophy

Goal: To provide a complete, street-optimized engine solution that delivers substantial performance improvements while prioritizing long-term reliability, refined drivability, and accessible enhancement potential for enthusiastic street use rather than extreme competition applications.

Focus: Enhanced low-speed torque for improved street response; strengthened bearing and fastening systems for extended service life; balanced performance characteristics suitable for diverse driving conditions; and comprehensive integration that minimizes installation complexity while maximizing real-world driving benefits.

Application & Integration Considerations

⚠️ Critical Usage Parameters & Recommendations:

• Application Specificity: Designed explicitly for street use; therefore, for continuous high-power applications such as circuit racing, HKS recommends the STEP Pro or STEP Pro+ variants instead

• Torque Application: 1,000 N·m capacity represents engineering estimates based on internal testing; consequently, actual usable torque will vary with specific vehicle implementation and driving conditions

• Supporting Systems: Auxiliary equipment including surge tanks and turbines not included; accordingly, appropriate complementary systems must be selected for optimal street performance

• Professional Installation: Recommended to ensure proper integration and optimal performance realization

🔧 Recommended Complementary Upgrades:

• Moderate Forced Induction: Street-appropriate turbo systems compatible with 1,000 N·m torque levels

• Fuel System Enhancement: Appropriate injector and pump upgrades to support increased displacement and power

• Cooling System: Enhanced street cooling solutions for sustained performance during spirited driving

• Engine Management: Street-focused ECU calibration optimizing drivability and part-throttle response

🎯 Primary Performance Characteristics:

• Enhanced Low-Speed Torque: Improved acceleration response in typical street driving RPM ranges

• Extended RPM Capability: 7,400 rpm limit allows flexibility while maintaining street-appropriate characteristics

• Refined Drivability: Balanced performance profile prioritizing smooth power delivery across diverse conditions

• Long-Term Reliability: Durability enhancements focused on extended service life under street use patterns

Strategic Advantages & Technical Distinctions

🛣️ Street-Specific Performance Calibration
Unlike competition variants, the STEP3 emphasizes low-speed torque enhancement and drivability refinement; consequently, it delivers performance improvements most noticeable and beneficial during typical street driving scenarios rather than optimizing for peak power or extreme RPM operation.

🔩 Service Life Prioritization Over Maximum Performance
The strengthened main bearing caps and advanced bearing selections demonstrate a clear priority on extended reliability; accordingly, this engine is engineered to maintain optimal condition across years of spirited street use rather than maximize short-term performance at the expense of longevity.

⚖️ Accessible Performance Enhancement Strategy
By providing substantial displacement increases and torque improvements within street-appropriate parameters, this engine offers meaningful performance gains without requiring the extreme supporting modifications or driving compromises associated with competition-focused powerplants.

🔄 Progressive Upgrade Pathway Recognition
HKS explicitly positions the STEP3 as the street-focused entry point within their engine hierarchy. Therefore, owners can begin with this optimized street solution. They have the understanding of clear upgrade paths to STEP Pro or STEP Pro+ variants should their usage patterns evolve toward competition applications.

Newly designed, fully machined I-beam connecting rod with 26% improved buckling strength (STEP Pro+ exclusive)

A special oil jet was created using a 3D printer to fit the I-section connecting rod.

Mirror-finished combustion chamber and intake/exhaust ports hand-finished by one of HKS’s most skilled engine builders

Machined piston made from high-temperature strength A2618 material,
with a special two-layer coating for Pro+.

Crank damper exclusively for VR43
(co-developed with ATI)

The crank pin diameter and corner radius have been enlarged to increase the torsional strength of the crank
(enlarged pin diameter is only available on STEP Pro+).

#2 and #3 bearing caps are remade with chromoly material for strength and line boring for improved accuracy
(STEP Pro & STEP Pro+)

Machined I-beam connecting rod bearing
(φ57 STEP Pro+ exclusive)

Exclusive emblem
DLC processed Pro+ exclusive emblem

Dedicated crank:
Asymmetric crank that combines increased strength and reduced inertia weight