Introduction: The 370Z’s Potential Unleashed

The Nissan 370Z has earned a loyal following among driving enthusiasts for its lightweight chassis, responsive VQ37VHR engine, and rear‑wheel‑drive dynamics. While the stock 332 horsepower provides ample excitement for many, serious power seekers quickly discover the limits of the naturally aspirated V6. Adding forced induction is the most effective way to transform the 370Z from a quick sports car into a genuine performance machine. Among the options available, the HKS Super Turbo Kit stands out as a complete, engineered system that delivers impressive gains without the headaches of a cobbled‑together setup. This article examines exactly how much power the HKS Super Turbo Kit adds, the real‑world results owners have achieved, and the true cost of bringing this level of performance to your 370Z.

What Is the HKS Super Turbo Kit?

HKS has been a dominant name in Japanese performance tuning for decades. Their Super Turbo Kit for the Nissan 370Z is a comprehensive forced‑induction system designed to bolt onto the stock engine with minimal modifications. Unlike generic turbo kits that require extensive fabrication, the HKS kit is engineered to integrate seamlessly with the 370Z’s chassis and engine bay. It includes a precision‑machined turbocharger, an air‑to‑air intercooler, fuel system upgrades, and a dedicated exhaust manifold.

Kit Variations for the Nissan 370Z

HKS offers multiple turbo kit variants, each tailored to different power goals and driving preferences. The most commonly installed kits for the 370Z are the HKS GTII Super Turbo Kit and the HKS GTIII Super Turbo Kit. The GTII utilizes a smaller, faster‑spooling turbocharger, making it ideal for street‑focused builds that prioritize low‑end torque and quick throttle response. The GTIII employs a larger turbo, capable of supporting higher peak horsepower numbers, appealing to owners who want maximum top‑end power for track days or drag racing. Both kits share the same core components, with the primary difference being the turbocharger sizing.

Components Included in the Kit

A complete HKS Super Turbo Kit typically includes:

  • HKS GTII or GTIII Turbocharger – Factory‑balanced and featuring billet compressor wheels for reduced lag.
  • Cast Stainless Steel Exhaust Manifold – Designed to match the turbo’s flange and improve exhaust flow.
  • Air‑to‑Air Intercooler – Large core with cast aluminum end tanks to lower intake air temperatures.
  • Aluminum Intercooler Piping – Mandrel‑bent tubing with silicone couplers for durability and flow.
  • Upgraded Fuel Injectors – Typically 550cc or larger to support the higher fuel demand.
  • Fuel Pressure Regulator – Ensures consistent fuel delivery under boost.
  • HKS Blow‑Off Valve – Plumbed to recirculate or vent to atmosphere, depending on tuning preference.
  • Full Exhaust System – Downpipe, front pipe, and cat‑back exhaust (sometimes optional, depending on retailer package).
  • ECU Tuning Software or Programmed ECU – Many kits include HKS’s own F‑CON or a flash tune from a trusted partner like Uprev or ECUTek.

Engineers at HKS have tuned these components to work in harmony, reducing the risk of issues like boost spikes, fuel starvation, or excessive heat soak that can plague less refined kits.

Real‐World Power Gains: From 332 to 450+ Horsepower

The core question for any performance enthusiast is “How much horsepower will I actually get?” The answer depends on the kit variant, the fuel used, and the quality of the tune. HKS rates the GTII kit at approximately 440‑450 wheel horsepower on 93 octane pump gas. The GTIII kit can push beyond 500 wheel horsepower with proper supporting modifications and higher octane fuel. To put that in perspective: a stock 370Z produces around 275‑285 wheel horsepower (due to drivetrain loss). The GTII kit adds roughly 160‑175 wheel horsepower, representing a power increase of nearly 60%.

Measured Crank vs. Wheel Power

It is important to distinguish between crank (flywheel) and wheel horsepower. The original article mentioned “up to 450 hp” at the crank—that is conservative. Most dyno tests on the GTII kit show wheel numbers in the 430‑450 whp range. For reference, the VQ37VHR engine in stock form is rated at 332 crank hp, but real‑world wheel figures typically land between 270 and 285 whp. Therefore, 430 wheel horsepower translates to approximately 510‑530 crank horsepower, depending on the drivetrain efficiency. Owners who have pushed the GTIII kit with E85 fuel have recorded 500+ wheel horsepower and torque numbers exceeding 450 lb‑ft at the wheels.

Torque Curves and Driving Feel

Power figures alone do not tell the whole story. The HKS Super Turbo Kit dramatically transforms the torque delivery. A naturally aspirated 370Z offers a gradual torque build that peaks around 5200 rpm. With the HKS kit, boost builds early—typically reaching full boost by 3500‑4000 rpm on the GTII variant. The result is a fat, flat torque curve that provides strong acceleration from 3000 rpm all the way to the 7500 rpm redline. Owners report that the car feels significantly faster in everyday driving, not just at wide‑open throttle. The GTII’s quick spool makes it particularly fun for street use, while the GTIII’s later, more aggressive boost curve rewards high‑rpm driving on the track.

Owner Experiences and Dyno Results

Looking at real forums like The370Z.com and MyG37.com, common owner feedback highlights the kit’s reliability when properly tuned. One documented build on the HKS GTII kit produced 443 whp and 396 lb‑ft on a modest pump‑gas tune. Another owner running the GTIII kit with E85 recorded 511 whp and 478 lb‑ft. These numbers align with HKS’s own marketing claims. Some owners who have paired the kit with upgraded fuel pumps, ported intake manifolds, and custom intercoolers have pushed beyond 550 whp, but those builds require additional supporting mods and a very skilled tuner.

It is worth noting that results can vary significantly based on the tuning approach. The HKS kit is known for its consistent quality, but the final tune—whether done via ECUTek, Uprev, or HKS’s own F‑CON—makes a large difference. Many professional tuners recommend a custom ECU calibration rather than relying solely on a base map to extract safe power and smooth drivability.

Pricing and Total Investment

The HKS Super Turbo Kit represents a significant financial commitment, but it is important to budget for more than just the box of parts. Below is a realistic breakdown of costs.

Kit Prices by Variant

  • HKS GTII Super Turbo Kit (370Z): $6,200 – $7,500 depending on retailer and included components (some packages include an exhaust system, others do not).
  • HKS GTIII Super Turbo Kit (370Z): $6,800 – $8,200 due to the larger turbocharger and sometimes a larger intercooler.

Popular retailers include Z1 Motorsports and Concept Z Performance, both of which offer the kits with optional add‑ons like upgraded fuel pumps or supporting gaskets.

Installation and Tuning Costs

Installation of a turbo kit on the 370Z is not a weekend garage project for most people. Expect labor charges between $1,200 and $2,500, depending on the shop’s hourly rate and whether they need to remove the engine or perform custom fabrication. The kit is designed to be a direct bolt‑on, but many shops charge extra for routing intercooler piping and fitting the exhaust.

Tuning is another essential cost. A professional custom tune using ECUTek or Uprev typically runs $500‑$1,000. Some owners choose a remote tune from a well‑known calibrator, which can be less expensive but requires datalogging and multiple revisions. A base map from the kit manufacturer may be included, but it is almost always worth investing in a custom tune to maximize power and ensure safety.

Hidden and Unexpected Costs

Several additional items often come up during installation:

  • Clutch Upgrade: With more than 400 lb‑ft of torque, the stock clutch will slip. A quality unit like the ACT Heavy Duty or South Bend Stage 2 costs $500‑$900 plus installation.
  • Fuel System Upgrades: While the kit includes injectors, many owners add a Walbro 450 lph fuel pump or a return‑style fuel system for consistent pressure under high boost. Budget $200‑$600.
  • Heat Management: Turbo blankets, header wrap, and oil coolers are recommended to keep under‑hood temperatures in check. Add $200‑$500.
  • Gauges: A boost gauge and wideband AFR gauge are essential for monitoring. Budget $200‑$400.

When all costs are factored in—kit, installation, tuning, clutch, fuel pump, and minor supporting items—the total investment for a reliable HKS Super Turbo Kit build is typically between $9,000 and $13,000. That is a substantial sum, but buyers receive a fully engineered system with proven results.

Is the HKS Super Turbo Kit Worth It?

Pros

  • Proven Power: Gains of 150‑200 wheel horsepower are realistic and repeatable.
  • Build Quality: Components are made from high‑grade materials (cast stainless manifold, billet compressor wheel).
  • Drivability: The GTII variant retains excellent low‑end torque, making the car feel strong in everyday driving.
  • Comprehensive Package: Fewer compatibility headaches compared to piecing together a turbo system from disparate brands.
  • Resale Value: HKS kits are well‑known and sought after in the used market; a complete kit can be sold if you decide to sell the car or go back to naturally aspirated.

Cons

  • High Initial Cost: The kit itself is expensive, and the total build cost approaches that of a supercharger system or a built motor swap.
  • Installation Complexity: Even a “bolt‑on” kit requires mechanical skill and time; improper installation can lead to boost leaks or reliability issues.
  • Need for Supporting Mods: The stock clutch, fuel pump, and cooling system often need upgrades, adding to the budget.
  • Heat and Stress: The VQ37VHR engine is robust, but pushing beyond 500 whp will shorten the lifespan of the engine if no internal modifications are made. Many owners choose to build the bottom end for higher power levels.
  • Emissions Concerns: In regions with strict emissions testing, the HKS kit may not pass visual inspection or smog checks.

Frequently Asked Questions

Will the HKS Super Turbo Kit damage my engine?

When properly installed and tuned on pump gas (91‑93 octane), the kit is safe and reliable. Many owners report tens of thousands of miles with no issues. Pushing the boost beyond the kit’s recommended limits or using aggressive tunes without supporting mods increases the risk of engine damage.

Do I need to upgrade the transmission?

The stock CD009 manual transmission and the 7‑speed automatic are capable of handling up to 500 lb‑ft without immediate failure, though clutch upgrades are strongly advised for manual cars. Automatic transmissions benefit from upgraded valve bodies and coolers if the car will be tracked.

Can I install the kit myself?

It is possible if you have advanced mechanical skills and tools. The kit is designed for bolt‑on installation, but you will need to remove the front bumper for the intercooler, run oil and coolant lines, and reroute the intake. A DIY install saves $1,200‑$2,500 but requires a few weekends and careful attention to detail.

What kind of fuel does the kit require?

HKS recommends 93 octane premium pump gas. For the GTIII kit, 91 octane is acceptable but may reduce power slightly. E85 is compatible with the larger injectors and can unlock significant additional power, but you must ensure the fuel system can support the higher flow rates.

Conclusion

The HKS Super Turbo Kit is one of the most refined and effective forced‑induction solutions for the Nissan 370Z. It adds 150‑200 wheel horsepower on pump gas, transforms the torque curve, and maintains the engine’s reliability when properly tuned. Real‑world dyno results confirm that a GTII kit can push the 370Z well past 400 wheel horsepower, while the GTIII kit reaches into the 500‑wheel‑horsepower territory. The total investment of $9,000‑$13,000 includes the kit, installation, tuning, and necessary supporting upgrades. For enthusiasts seeking a streetable, track‑capable 370Z with undeniable punch, the HKS Super Turbo Kit delivers a compelling balance of engineering, performance, and durability. It is a serious upgrade for serious drivers—one that turns a good sports car into an unforgettable one.