Introduction: Why Upgrade to the HKS SSQV Blow Off Valve on a 600 HP Nissan GT-R

Upgrading the blow off valve on a high-performance Nissan GT-R is not merely an aesthetic or auditory modification; it is a functional enhancement that can significantly improve throttle response, turbocharger longevity, and overall engine efficiency. The HKS Super Sequential Blow Off Valve (SSQV) has long been regarded as one of the most reliable and performance-oriented aftermarket blow off valves available. For a Nissan GT-R producing 600 horsepower, the factory blow off valve often becomes a restriction under elevated boost pressures, leading to compressor surge and sluggish throttle transitions. The HKS SSQV addresses these issues with a dual-stage design that vents boost pressure smoothly at high loads while preserving driveability at low engine speeds.

This comprehensive guide provides a detailed, step-by-step walkthrough for installing the HKS SSQV Blow Off Valve on a Nissan GT-R specifically tuned to the 600 horsepower threshold. Each phase of the installation is covered in depth, from tool preparation and safety protocols to final tuning and performance validation. By following this guide, you will ensure a precise fit, leak-free connections, and optimal valve operation that enhances the driving character of your GT-R.

Before beginning any work, it is essential to understand that modifying the intake and boost control systems of a high-output vehicle requires careful attention to detail. The HKS SSQV is designed to handle boost pressures well beyond the stock configuration, but improper installation can lead to vacuum leaks, erratic idle, or reduced performance. For more information on the HKS SSQV product line and its specifications, consult the official HKS SSQV product page.

Tools and Materials Required for Installation

Having the correct tools and components on hand before you start will streamline the installation process and prevent unnecessary delays. Below is a comprehensive list of everything you will need to complete the HKS SSQV installation on a Nissan GT-R.

Essential Tools

  • Metric socket set (particularly 10 mm, 12 mm, 14 mm sockets and a ratchet with extensions)
  • Combination wrenches (10 mm, 12 mm, 14 mm for hard-to-reach fasteners)
  • Flathead and Phillips screwdriver set (for hose clamps and electrical connectors)
  • Torque wrench (capable of 5–20 Nm range for delicate fittings and 20–50 Nm for mounting bolts)
  • Vacuum hose removal tool or needle-nose pliers for stubborn hose connections
  • Trim removal tools (if accessing piping behind engine covers or underbody panels)
  • Safety glasses and mechanic gloves

Included and Required Components

  • HKS SSQV Blow Off Valve Kit (including valve body, mounting flange, gasket, bolts, and vacuum hose adapter)
  • Replacement silicone vacuum hose (4 mm or 5 mm inner diameter, depending on your GT-R model year)
  • Stainless steel hose clamps (two for the intake pipe connection, two for vacuum line connections)
  • Thread-locking compound (medium-strength, such as Loctite 242, for bolt retention)
  • Shop rags and a vacuum cleaner for cleaning debris from the engine bay

If your GT-R uses an aftermarket intercooler or hard intake pipes, verify compatibility with the HKS SSQV mounting flange. Some vehicles may require an additional adapter plate, which can be sourced from performance retailers or directly from HKS. A useful resource for verifying fitment is the Nissan GT-R Owners Club forum, where many members have documented their SSQV installation experiences.

Preparation and Safety Protocols

Proper preparation is critical when working on a vehicle that generates 600 horsepower. The following steps will ensure a safe and efficient workflow.

Work Area and Vehicle Positioning

  • Park the Nissan GT-R on a flat, level surface inside a well-ventilated garage or on a clean driveway. Avoid working on grass or gravel, where dropped fasteners can be lost.
  • Engage the parking brake and place wheel chocks behind the rear tires to prevent any unintended movement.
  • If the vehicle has been driven recently, allow the engine to cool completely. The intake piping and turbocharger components can retain heat well above 100°C (212°F) even after the engine is turned off.

Electrical and System Disconnection

  • Disconnect the negative battery terminal using a 10 mm wrench or socket. This prevents accidental short circuits and protects sensitive ECU components when working near electrical connectors.
  • If your GT-R is equipped with an aftermarket boost controller or standalone ECU, note the existing vacuum line routing. Taking a photograph before disassembly will help during reinstallation.
  • Relieve any residual boost pressure by loosening the oil filler cap slightly and listening for air release. This step is optional but recommended for safety when removing pressurized intake pipes.

Component Inspection Before Disassembly

  • Visually inspect all intake pipes, couplers, and hose clamps for signs of wear, cracks, or oil residue. A 600 HP setup often generates higher than normal crankcase pressure, which can accelerate deterioration of rubber components.
  • Check the existing blow off valve for any evidence of leakage, such as oily film around the valve flanges or vacuum line nipples.
  • Verify that the HKS SSQV kit matches the bolt pattern and flange orientation of your specific GT-R model year (2007–2018 R35 or R32–R34 models). While the installation principles are similar, flange offsets may vary.

Removing the Factory Blow Off Valve

The factory blow off valve on the Nissan GT-R is located on the charge air piping between the intercooler and the throttle body. Removing it requires careful disassembly of the intake tract.

Accessing the Intake Piping

  • Remove any engine covers or trim panels that obstruct access to the intake piping. On the R35 GT-R, this includes the plastic engine cover, which is held by four 10 mm bolts and two push clips.
  • Identify the rubber couplers connecting the intake pipe to the intercooler outlet and throttle body inlet. Loosen the hose clamps on both sides using a flathead screwdriver or 8 mm socket, depending on clamp type.
  • Carefully separate the intake pipe from the intercooler and throttle body. It may be necessary to gently twist the pipe to break the silicone coupler seal. Do not use excessive force, as aluminum pipes can be damaged.

Disconnecting Vacuum Lines and Electrical Connectors

  • Locate the vacuum line attached to the factory blow off valve. On most GT-R models, this is a 4 mm silicone hose running from the intake manifold or a dedicated boost reference port.
  • Using needle-nose pliers, compress the hose clamp and slide it away from the valve nipple. Gently twist the hose while pulling it free. If the hose is stuck, use a vacuum hose removal tool to avoid tearing the rubber.
  • If your vehicle has a factory boost pressure sensor or solenoid near the blow off valve, disconnect its electrical connector by pressing the release tab and pulling straight out. Do not pull on the wires themselves.

Unbolting the Factory Valve

  • Using a 12 mm socket or wrench, remove the two bolts securing the blow off valve flange to the intake pipe. The bolts are typically oriented vertically or horizontally depending on the model.
  • Some GT-R models use a gasket between the valve and the flange. Inspect this gasket for damage; if it is reusable, set it aside. A new gasket is often included with the HKS SSQV kit.
  • Lift the factory blow off valve straight off the mounting flange. Be prepared for a small amount of residual oil or condensation to drip from the intake pipe. Wipe the area clean with a shop rag.

Installing the HKS SSQV Blow Off Valve

With the factory valve removed and the mounting surface cleaned, you can proceed to install the HKS SSQV. This section covers flange preparation, valve mounting, and vacuum line routing.

Preparing the Mounting Flange

  • Clean the mounting flange on the intake pipe thoroughly using a solvent or brake cleaner applied to a lint-free cloth. Remove all traces of old gasket material, oil, and dirt.
  • Apply a small amount of medium-strength thread-locking compound to the threads of the new mounting bolts provided in the HKS kit. This prevents vibration-induced loosening over time.
  • Position the new gasket (or reuse the factory gasket if it is in perfect condition) over the flange studs or bolt holes. Ensure the gasket aligns perfectly with the valve opening.

Mounting the HKS SSQV Valve Body

  • Place the HKS SSQV valve onto the flange, ensuring the airflow arrow on the valve body matches the direction of air travel through the intake pipe. This is crucial for proper valve operation.
  • Insert the two mounting bolts and tighten them in a cross-pattern sequence to ensure even compression of the gasket. Use a torque wrench to tighten the bolts to the manufacturer's specification, typically 8–10 Nm (70–88 in-lb). Overtightening can crack the aluminum flange or deform the valve body.
  • Reattach the intake pipe to the intercooler outlet and throttle body inlet. Tighten the hose clamps evenly using a screwdriver or socket. Do not overtighten, as this can damage the silicone couplers. A torque of 3–5 Nm (26–44 in-lb) is usually sufficient for standard worm-gear clamps.

Adjusting the SSQV Spring Tension

  • The HKS SSQV features an adjustable spring tension via an adjustment ring on the valve body. For a 600 HP GT-R running 18–22 psi of boost, the spring tension should be set to a medium preload. Turning the adjustment ring clockwise increases spring tension, requiring more vacuum to open the valve.
  • Start with the adjustment ring set at the factory middle position (usually indicated by a dimple or marking on the body). After installation, you can fine-tune this setting based on driveability feedback.
  • If the valve opens too early (causing a low-speed stumble), increase spring tension slightly. If it opens too late or flutters under high boost, reduce tension. Detailed tuning guidance can be found in the HKS SSQV installation and tuning manual.

Routing and Connecting the Vacuum Hose

  • The HKS SSQV requires a dedicated vacuum reference signal from the intake manifold. Do not use a boost pressure source, as the valve is designed to open under vacuum and remain closed under positive pressure.
  • Connect the included silicone vacuum hose to the barbed fitting on the SSQV. Route the hose to the intake manifold vacuum port using a path that avoids hot surfaces such as exhaust manifolds or turbocharger housings.
  • Cut the vacuum hose to an appropriate length, leaving enough slack for engine movement. Use stainless steel clamps on both ends of the hose connection. A loose vacuum line is the most common cause of blow off valve malfunction.
  • If your GT-R has multiple vacuum ports, use the port that previously supplied the factory blow off valve. This ensures the same signal strength and prevents interference with other vacuum-operated systems such as the brake booster or bypass valves.

Finalizing the Installation and Leak Testing

After the mechanical installation is complete, you must verify that all connections are secure and leak-free before starting the engine.

Visual and Physical Inspection

  • Double-check all hose clamps on the intake piping, vacuum lines, and the blow off valve flange. Every clamp should be snug but not crushing the hose material.
  • Ensure the vacuum hose is not kinked or pinched between engine components. A kinked hose can restrict airflow and cause the valve to open erratically.
  • Reinstall any engine covers or trim panels that were removed during the installation. Be careful not to pinch any wires or hoses under the covers.

Battery Reconnection and Initial Startup

  • Reconnect the negative battery terminal and tighten the clamp securely. If your GT-R has an aftermarket ECU, verify that the battery voltage is stable before starting.
  • Turn the ignition key to the “ON” position without starting the engine. Listen for the fuel pump priming and check the dashboard for any warning lights. If the check engine light remains illuminated or flashes, investigate potential issues before proceeding.
  • Start the engine and allow it to idle for several minutes. Monitor the idle quality for any roughness or surging. A properly installed HKS SSQV should not affect idle speed or stability.

Leak Detection Procedures

  • With the engine idling, listen carefully for any hissing or whistling sounds around the blow off valve flange, intake pipe connections, and vacuum hose ends. These indicate air leaks that must be rectified immediately.
  • Using a soapy water spray (a mixture of dish soap and water in a spray bottle), lightly mist all connections. Bubbles will form at the location of any leak. If bubbles appear, tighten the connection and retest.
  • For a more thorough check, pressurize the intake system to 15–20 psi using a boost leak tester. This is a highly recommended step for high-horsepower setups, as even minor leaks can cause significant performance degradation. Detailed instructions for building and using a boost leak tester can be found in this GT-R forum guide.

Testing and Performance Validation

Once you have confirmed there are no leaks, it is time to test the blow off valve under real driving conditions. Proper testing ensures the valve operates correctly across the entire boost range.

Static Rev Test

  • With the engine at operating temperature, rev the engine in neutral or park to approximately 3,000–4,000 RPM. Listen for the characteristic sound of the HKS SSQV: a distinct “psssh” or chirp as the valve vents when the throttle closes.
  • If the valve does not sound immediately or sounds weak, check the vacuum line connection and spring tension setting. A valve that is too stiff will not open fully, producing a muffled or flutter sound.

Road Test Protocol

  • Take the Nissan GT-R for a short test drive on a safe road or track. Begin with light throttle applications and gradually increase to medium throttle loads. The blow off valve should operate each time you close the throttle after building boost.
  • Monitor the boost gauge (factory or aftermarket) to ensure peak boost levels remain consistent with pre-upgrade values. A well-functioning SSQV should not affect boost pressure or turbo spool characteristics.
  • Pay attention to transient throttle response. One of the primary benefits of the HKS SSQV is improved response between gear shifts. If you notice hesitation or a delay when reopening the throttle, the valve may be leaking boost, requiring further adjustment.

Data Logging and AFR Monitoring

  • If your GT-R is equipped with a wideband oxygen sensor and data logging system, review the air-fuel ratio (AFR) logs during the test drive. A properly functioning blow off valve will not cause fuel enrichment or lean spikes during gear changes.
  • An AFR that goes excessively lean (above 14.7:1) when the throttle closes and the valve vents may indicate a vacuum leak or incorrect spring tension. Adjust the spring preload in small increments and retest.
  • For vehicles running aggressive tune files with high boost (22+ psi), it is prudent to confirm that the ECU can compensate for the increased airflow from the SSQV. Some aftermarket tuners recommend recalibrating the mass airflow sensor or load calculations after changing the blow off valve. Reference Ecotek’s knowledge base on blow off valve calibration for deeper technical insights.

Maintenance Tips and Long-Term Care

To ensure the HKS SSQV continues to perform reliably over the life of your 600 HP GT-R, adhere to the following maintenance practices.

  • Inspect vacuum hoses annually. Silicone vacuum hoses can harden and crack after prolonged exposure to underhood heat. Replace them at the first sign of brittleness.
  • Clean the blow off valve internals every 20,000 miles. The SSQV can accumulate oil vapor and carbon deposits from the crankcase ventilation system. Disassemble the valve (carefully noting the orientation of the internal spring and piston) and clean all components with a non-residue solvent.
  • Re-grease the O-ring seal during cleaning using a silicone-based lubricant. This prevents the seal from drying out and causing vacuum leaks.
  • Monitor for boost creep. In rare cases, a blow off valve can fail to open fully at high RPM, causing compressor surge. If you hear a fluttering sound at full boost, reduce spring tension immediately and inspect for obstructions in the vacuum line.

Conclusion

Installing the HKS SSQV Blow Off Valve on a 600 horsepower Nissan GT-R is a rewarding upgrade that delivers tangible performance benefits alongside the signature sound enthusiasts appreciate. The sequential design of the SSQV allows it to operate efficiently under both low-load and high-boost conditions, protecting the turbochargers from surge while preserving crisp throttle response. By following the detailed steps outlined in this guide—from meticulous preparation and careful removal of the factory valve to precise mounting, vacuum line routing, and thorough leak testing—you can complete the installation with confidence.

Remember that the adjustment ring on the SSQV gives you fine control over valve behavior, so take the time to dial in the spring tension after installation. A few minutes of tuning effort will yield an improvement in driveability that transforms the character of your GT-R. With the HKS SSQV properly installed and maintained, your 600 HP Nissan GT-R will deliver a driving experience that is both more responsive and more exhilarating on every journey.