Nissan GTR R35 VR38DETT Stage 3 Cylinder Head Package | CNC Machined Performance Head
The cylinder head plays a critical role in determining how efficiently an engine moves air, manages combustion, and withstands high cylinder pressure. While the factory VR38 cylinder head is exceptionally capable, it was designed to meet OEM production requirements rather than support the airflow and cylinder pressures associated with extreme horsepower.
The SZM Stage 3 Cylinder Head Package combines precision CNC machining, combustion chamber development, cylinder head reinforcement, and complete valvetrain machining to increase airflow, improve combustion efficiency, and provide the durability required for high-boost VR38DETT engines.
Rather than simply removing material, every machining operation is performed with a specific engineering objective whether that's improving airflow, maintaining air velocity, strengthening the casting, or ensuring every valve operates with precise geometry.
CNC Machining & Engineering Processes
Initial Inspection & Preparation
The preparation process depends on whether the cylinder head is brand new or previously used.
Brand-new OEM Nissan GTR R35 cylinder heads proceed directly to the required machining operations. Once all CNC machining has been completed, the cylinder head undergoes chemical and ultrasonic cleaning to remove aluminum chips, cutting fluids, abrasives, and any remaining machining debris before assembly.
Used cylinder heads require additional inspection before machining begins. Each casting is pressure tested and inspected for cracks, while the deck surface is checked for distortion to verify the cylinder head remains structurally suitable for high-performance use. Beginning with a sound casting ensures every subsequent machining operation is performed on a reliable foundation.
CNC Intake & Exhaust Port Development
As airflow demand increases, the factory intake and exhaust ports eventually become a restriction. Simply increasing boost pressure cannot compensate for limitations in airflow, making cylinder head development essential for engines targeting four-digit horsepower.
Our CNC porting program reshapes the intake and exhaust runners using machining strategies developed specifically for the VR38 cylinder head. The valve throat, bowl area, short-side radius, and runner transitions are carefully optimized to improve airflow while maintaining the air velocity required for efficient cylinder filling.
Unlike hand porting, CNC machining produces virtually identical ports across all six cylinders. Consistent airflow improves cylinder-to-cylinder balance, combustion stability, tuning accuracy, throttle response, and overall engine efficiency.
CNC Combustion Chamber Development
Increasing airflow is only one part of building a high-performance cylinder head. The combustion chamber itself has a significant influence on combustion efficiency, knock resistance, and thermal management.
Each combustion chamber is CNC machined to achieve a precise chamber volume while removing sharp edges that can create localized hot spots under high cylinder pressure. The increase in chamber volume also slightly reduces the static compression ratio, providing greater tuning flexibility and allowing the engine to safely support higher boost pressures.
Matching chamber volumes across all cylinders also promotes balanced combustion and more consistent engine performance.
Cylinder Head Reinforcement & Precision Decking
High cylinder pressure places enormous loads on the VR38DETT cylinder head, particularly around the combustion chambers and head stud bosses. To increase the strength of the casting, every SZM Stage 3 Nissan GTR R35 cylinder head is fitted with the SZM GT-R R35 Jack Bolt system and reinforced in two factory water jacket areas. These reinforced sections, shown in blue, add material where the casting experiences the highest stress, increasing cylinder head rigidity without compromising the engine's cooling system.
Once all machining and reinforcement work has been completed, the cylinder head is precision CNC decked to restore absolute flatness and produce an exceptionally smooth sealing surface. A perfectly machined deck allows the cylinder head to mate evenly with the engine block, helping the SZM Fire O-Ring head gasket system maintain a reliable seal under extreme boost and cylinder pressure.
Valve Guide & Valve Seat Machining
Accurate valve control begins with correctly machined valve guides and valve seats.
The cylinder head is machined to accept upgraded valve guides before the new valve seats are installed and precision cut using a multi-angle profile. Correct guide geometry and valve seat machining are essential for smooth valve operation, proper sealing, efficient airflow, and long-term durability under high engine speeds.
Valvetrain Setup
Valve geometry is one of the most important factors affecting engine reliability at high RPM.
Every valve shim is individually measured and selected to achieve the valve lash specified by the camshaft manufacturer. Proper valve clearance allows for thermal expansion while maintaining accurate valve timing throughout the engine's operating range.
Installed spring height is also measured for every valve to ensure consistent spring pressure across the entire cylinder head. Uniform spring pressure improves valve control, reduces harmonics, and helps prevent valve float during high-speed operation.
Final Assembly
After every machining operation has been completed, each component is thoroughly cleaned, measured, and inspected before assembly begins.
Valves, springs, retainers, shims, camshafts, and all valvetrain components are assembled using measured specifications rather than nominal values. Every critical clearance is verified one final time before the completed cylinder head is prepared for installation.
The finished SZM Stage 3 VR38 cylinder head delivers improved airflow, optimized combustion chamber design, greater structural rigidity, precise valvetrain geometry, and the durability required for high-performance Nissan GTR R35 engines operating under extreme boost and horsepower levels.
GSC Power-Division head components
GSC Bronze Valve Guides (GSC3046-12)/(GSC3143.001- 12)
The factory intake and exhaust valve guides are replaced with high-strength GSC bronze valve guides to improve wear resistance, heat transfer, and valve stability under high engine speeds. The intake guides feature an integrated stopper, while the exhaust guides incorporate a precision depth step, ensuring accurate installation and consistent valve geometry across every cylinder.
GSC +1mm Performance Valves (GSC2057-12)/(GSC2058-12)
The factory intake and exhaust valves are replaced with GSC +1mm performance valves to increase the cylinder head's airflow capacity. The larger valve diameter increases valve curtain area, allowing greater airflow into and out of the combustion chamber. The intake valves feature a flat-face design, while the exhaust valves are manufactured from a high-temperature super alloy with a 6.6mm stem to withstand the extreme temperatures produced by high-boost turbocharged engines.
GSC Viton Valve Stem Seals (GSC1050)
High-quality Viton valve stem seals provide excellent resistance to heat, oil, and fuel exposure while precisely controlling the amount of oil reaching the valve guides. This helps reduce oil consumption, minimizes carbon deposits, and maintains reliable sealing throughout extended service life.
GSC Extreme Pressure Valve Springs & Titanium Retainers (GSC5089)
Higher lift camshafts and increased engine speed require greater valve control than the factory springs can provide. GSC conical valve springs deliver the spring pressure needed to prevent valve float at high RPM, while lightweight titanium retainers reduce valvetrain mass and improve stability at elevated engine speeds.
GSC Billet S3 Camshaft Set (GSC7045S3)
The GSC S3 billet camshafts feature revised lift and duration profiles that allow the cylinder head to take full advantage of the increased airflow provided by CNC porting and larger valves. This improves cylinder filling, increases airflow at higher engine speeds, and supports greater horsepower potential throughout the RPM range.
SZM Beryllium Valve Seats (Set of 24)
The factory valve seats are replaced with precision-machined beryllium copper seats that transfer heat away from the valves more efficiently than conventional seat materials. Lower valve temperatures improve durability, reduce valve recession, and maintain reliable sealing during prolonged high-load operation.
SZM GT-R R35 Jack Bolt
Extreme cylinder pressure places significant stress on the cylinder head, particularly around the head stud bosses. SZM Jack Bolt kit reinforce these critical areas by increasing the rigidity of the casting and reducing cylinder head movement under high combustion loads. The additional support helps maintain more consistent head gasket clamping force, improving sealing reliability in high-boost and four-digit horsepower VR38DETT engines.
Built for Customers Who Refuse to Compromise
The SZM Stage 3 VR38 Cylinder Head Package is engineered for enthusiasts and racers looking to maximize the performance of their Nissan GT-R R35 VR38DETT engine. Combining advanced CNC machining, premium valvetrain components, and proven engineering, this package delivers the airflow, durability, and reliability required for high-boost, high-horsepower applications.
Whether you're building a street-driven GTR, drag car, or standing-mile vehicle, the SZM Stage 3 Cylinder Head Package provides the foundation needed to support modern turbocharger upgrades and unlock the full potential of your VR38DETT engine.