Description

The HKS COMPLETE ENGINE VR38DETT 4.3L STEP Pro+ represents the absolute pinnacle of HKS’s engine building expertise. Consequently, it serves as a fully assembled, competition-ready powerplant. It is engineered to withstand extreme torque loads up to 1,900 N·m. This is while simultaneously delivering exceptional durability and precision performance.

This ultimate complete engine builds upon the proven STEP Pro foundation. Moreover, it incorporates significant structural enhancements. This includes a newly developed asymmetrical crankshaft, I-beam connecting rods with 26% greater buckling strength, and advanced materials science applications throughout.

Designed exclusively for high-end circuit driving, time attack competition, and drag racing applications, this engine therefore embodies HKS’s decades of motorsport experience. This experience is translated into a turnkey powerplant solution for those demanding uncompromising performance and reliability.

Product Highlights

🏆 Ultimate Torque Capacity for Extreme Competition Applications
Engineered specifically to withstand torque levels up to 1,900 N·m—substantially beyond conventional engine capabilities—the STEP Pro+ incorporates revolutionary structural enhancements.

For instance, it features an asymmetrical crankshaft with enlarged pin diameters. Alongside this, it includes a fully redesigned I-beam connecting rod architecture. Consequently, it addresses the specific demands of modern high-torque competition environments where, by comparison, conventional engines would experience rapid failure.

🔩 Advanced Materials Science & Precision Manufacturing Integration
Utilizing ion-nitrided steel crankshafts with deepened hardened layers, this engine also incorporates specially machined I-section connecting rods.

Furthermore, it integrates 3D-printed oil jets tailored to the new rod geometry, thereby demonstrating sophisticated manufacturing integration.

Additionally, critical components like #2 and #3 bearing caps are remanufactured from chromoly material. Super thermal conductive copper alloy valve seats and phosphor bronze guides collectively optimize thermal management under extreme loads.

⚖️ Asymmetric Crankshaft Design for Optimal Strength-to-Weight Balance
The innovative asymmetrical crankshaft design strategically increases the critical cross-sectional area only between the #5 and #6 pins—where stress concentrations are highest. Simultaneously, it maintains optimized counterweight balancing. This intelligent approach, therefore, maximizes torsional rigidity where most needed while minimizing unnecessary weight increases. Ultimately, it creates an ideal balance for high-RPM operation.

🎨 Meticulous Hand-Finishing by Master Engine Builders
Beyond precision machining, this engine benefits from meticulous hand-finishing of combustion chambers and intake/exhaust ports by HKS’s most skilled technicians. In addition to this artisanal approach, mirror-finished surfaces optimize airflow and combustion characteristics in ways that automated processes alone cannot achieve.

Technical Specifications

Product Name: COMPLETE ENGINE VR38DETT 4.3L STEP Pro+

Application Focus: Circuit driving, time attack, drag racing, and other high-end competition use

Structural & Performance Parameters:

• Expected Torque Capacity: Up to 1,900 N·m (dependent on supporting systems and conditions)

• Displacement: 4,255cc (vs. factory 3,799cc)

• Bore: 95.5mm (maintained from HKS 4.3L kit)

• Stroke: 99.0mm (increased from factory 88.4mm)

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

• Allowable RPM: 7,400 rpm (vs. factory 7,000 rpm)

Critical Component Enhancements:

Crankshaft System:

• Material: Nitrided steel with ion nitride surface treatment

• Design: Asymmetric configuration with enlarged φ57 pin diameter (STEP Pro+ exclusive)

• Enhancements: 10mm lengthened front end to prevent pulley fretting

• Pulley: VR43-specific damper co-developed with ATI

Connecting Rod Assembly:

• Design: Newly developed fully machined I-beam section (STEP Pro+ exclusive)

• Strength Improvement: 26% increased buckling strength over previous designs

• Bearings: ACL narrow width machining for optimal oil film maintenance

• Oil Jets: 3D-printed specifically for I-section rod geometry

Cylinder Head & Valvetrain:

• Materials: Super thermal conductive copper alloy seats, phosphor bronze guides

• Processing: Step removal and polishing around seats, combustion chamber mirror finish

• Camshafts: HKS IN: 270°/11mm lift, EX: 278°/11mm lift

• Valve Springs: HKS reinforced products with sheet lapped valves

Block & Lower Assembly:

• Reinforcement: #2 & #3 chromoly bearing caps with line boring for journal accuracy

• Fasteners: HKS M12 stud bolts (625+), ARP reinforced head studs

• Bearings: ACL main and connecting rod bearings selected through extensive testing

Piston System:

• Material: High-temperature strength A2618 with special two-layer molybdenum coating

• Design: Machined specifically for Pro+ application with optimized thermal characteristics

Exclusive Emblem: DLC-processed STEP Pro+ identification badge

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

Performance & Engineering Philosophy

Goal: To create a complete, turnkey engine solution capable of withstanding the extreme torque and thermal demands of modern high-end competition; accordingly, it must deliver consistent, reliable performance across diverse racing disciplines.

Focus: Structural integrity under extreme torque loads remains paramount; furthermore, thermal management for sustained high-load operation, precision balancing for high-RPM capability, and comprehensive integration of advanced materials and manufacturing techniques collectively exceed the capabilities of individual component upgrades.

Application & Integration Considerations

⚠️ Critical Usage & Limitation Acknowledgments:

• Torque Estimates: 1,900 N·m capacity represents engineering estimates based on internal testing; consequently, actual usable torque varies with vehicle specifications, conditions, and supporting systems

• Auxiliary Exclusions: Surge tanks, turbines, and other ancillary equipment are not included; instead, this engine is designed for integration with comprehensive competition systems

• Professional Installation: Mandatory given the precision tolerances and specialized knowledge required

• Supporting Systems: Requires appropriate turbo, fuel, cooling, and management systems to realize potential

🔧 Recommended Supporting Components:

• Forced Induction: HKS GT5565_BB or similar high-capacity turbo systems

• Fuel Delivery: HIGH-FLOW SURGE TANK system with appropriate injector and pump capacity

• Cooling: GT1000SPEC intercooler and comprehensive thermal management

• Management: Professional competition-grade ECU with appropriate sensors and controls

🎯 Primary Competition Applications:

• Time Attack: Where consistent high-load operation demands exceptional thermal and structural durability

• Circuit Racing: Requiring balanced performance across diverse corners and straights

• Drag Competition: Demanding instantaneous torque delivery and rapid spool characteristics

• Endurance Events: Where reliability under sustained stress proves paramount

Strategic Advantages & Technical Innovations

🏗️ Holistic Engineering Approach
Unlike assembled-from-components engines, the STEP Pro+ benefits from integrated design; specifically, its crankshaft, connecting rod, piston, and block enhancements work synergistically rather than as isolated upgrades.

🔥 Advanced Thermal Management Architecture
From copper alloy valve seats to specially coated pistons and optimized oil jet placement, every element addresses the extreme thermal challenges of 1,900 N·m operation; therefore, it provides comprehensive heat dissipation.

⚙️ Precision-Weighted Asymmetry
The strategic application of additional material only where stress concentrations demand it represents sophisticated engineering judgment; as a result, it prioritizes function over symmetry for optimal performance.

🛠️ Turnkey Competition Solution
As a complete engine rather than a component kit, the STEP Pro+ eliminates compatibility concerns, assembly tolerance stacking, and balancing uncertainties that can otherwise plague built-up competition engines.

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