Unlocking Serious Horsepower: The Stillen Supercharger for Infiniti G37

The Infiniti G37 has long been celebrated as a near-perfect blend of Japanese luxury and rear-wheel-drive performance. Under the hood, its 3.7-liter VQ37VHR V6 engine delivers a robust 330 horsepower stock, backed by silky throttle response and a high-revving nature. But for owners who crave more—more mid-range punch, more top-end rush, and more of the visceral thrill that only forced induction can provide—the Stillen Supercharger kit stands as one of the most proven and widely respected routes to big power. At approximately $4,500 for the core kit and offering documented gains of up to +125 horsepower at the wheels, the Stillen supercharger transforms the G37 into a genuine performance machine capable of challenging far more expensive sports cars. In this comprehensive guide, we dive deep into every aspect of this upgrade—from the engineering behind the kit to installation realities, tuning nuances, real-world driving impressions, and long-term ownership considerations.

Why the Stillen Supercharger Kit?

The VQ37VHR engine is fundamentally a strong and responsive platform, but its naturally aspirated design leaves significant headroom. While bolt-on modifications such as intake, exhaust, and headers can yield modest gains (usually 20-30 horsepower), a properly engineered supercharger system offers a step-change in output that fundamentally alters the car’s character. Stillen is not an off-brand player; the company has been developing performance parts for Nissan and Infiniti platforms since the 1980s, and their supercharger kit for the G37 is the result of extensive R&D, including countless hours of dyno testing and real-world validation. The kit is CARB-compliant (California Air Resources Board) for the G37 coupe, sedan, and convertible models with the 7-speed automatic transmission, making it a legitimate street-legal upgrade in all 50 states. This CARB approval is a major selling point for enthusiasts who want power without sacrificing legal compliance or dealing with annual smog-check headaches.

Kit Contents and Key Components

Before diving into installation and gains, it’s important to understand exactly what the $4,500 investment buys. The Stillen supercharger kit includes:

  • Vortech V3 Si-Trim Supercharger Unit – A compact, self-contained centrifugal supercharger that runs quietly and efficiently. Vortech is a leading name in centrifugal blowers, and the V3 features a helical-geared drive system for reduced noise compared to older straight-cut gear designs.
  • Cast Aluminum Intake Manifold – Replaces the factory intake plenum and incorporates integrated charge-air distribution for even airflow to all six cylinders. The manifold also features a bypass valve and integrated bypass-actuator provisions.
  • Air-to-Water Intercooler System – Unlike many older kits that rely on air-to-air intercoolers, Stillen uses an air-to-water charge cooler. This keeps intake air temperatures extremely low, even during sustained hard driving, and avoids the packaging difficulties of mounting a large air-to-air core behind the bumper. The system includes a front-mounted heat exchanger, electric water pump, and reservoir.
  • High-Flow Fuel Injectors (650cc) – To support the added airflow, the kit includes upgraded injectors that replace the factory units.
  • Fuel Pump Voltage Booster – Raises fuel pump voltage to maintain fuel pressure at high boost levels, ensuring the engine doesn't lean out under load.
  • Belt Drive System – A dedicated serpentine belt and tensioner assembly that drives the supercharger from the crankshaft pulley. The belt is routed away from the factory alternator and A/C belts, maintaining reliability.
  • ECU Calibration (Uprev OS Tune) – The kit comes with a pre-calibrated ECU tune via the Uprev operating system, loaded onto an ECUTek cable or a Uprev license flash. This is essential for proper air/fuel ratios and ignition timing. Stillen provides a base map that is safe for 91-octane fuel.
  • All Necessary Hoses, Clamps, and Mounting Hardware

Optional upgrades available from Stillen include a larger crank pulley for higher boost (around 8-9 psi instead of the standard 6 psi), a nitrous Express water/methanol injection kit for cooling, and a triple-pass heat exchanger for extreme track use.

Installation: What to Expect

Installing a supercharger is not a weekend project for a novice, but it is within the reach of a skilled DIY mechanic with proper tools, a lift or jack stands, and a willingness to follow detailed instructions. Stillen provides an excellent install guide, and the kit is designed to be a straightforward bolt-on affair. However, there are several critical steps that determine whether the final result is smooth and reliable or plagued with issues.

Preparation

Before touching the car, gather all tools: metric socket set, torque wrenches, a serpentine belt tensioner tool, a coolant fill funnel, and a laptop with the Uprev software for flashing the ECU. It is also wise to flush the engine coolant and replace the spark plugs with new ones (NGK LFR6AIX-11, gapped to 0.032” recommended) as the supercharger will demand a strong ignition system. Likewise, consider upgrading the radiator to a Koyo or CSF unit if the car will see regular track duty, as heat management becomes more critical.

Step 1 – Remove Engine Covers and Belts

Remove the engine beauty cover, air intake duct, factory air box, and the intake manifold. Drain coolant from the radiator. Remove the drive belt and loosen the alternator to gain access to the front of the engine.

Step 2 – Install the Supercharger Mounting Bracket and Pulley

The kit includes a cast-aluminum bracket that bolts to the front of the engine, replacing the stock belt tensioner location. The supercharger itself mounts on this bracket, positioning the blower near the passenger side of the engine bay. Carefully torque all bracket bolts to the specified values (usually 35-40 ft-lb). Run the new serpentine belt according to the diagram in the instructions.

Step 3 – Replace the Intake Manifold

The factory intake manifold is removed and replaced with the Stillen cast unit. This manifold includes provisions for the charge-air connections. Apply a thin bead of RTV silicone to the gasket surfaces for a leak-free seal. Install the intercooler core (the heat exchanger) behind the front bumper, mount the electric water pump, and route the hoses. Fill the intercooler system with a 50/50 mix of distilled water and antifreeze or pure water with a corrosion inhibitor (if not in freezing climates).

Step 4 – Fuel System Modifications

Swap the factory fuel injectors for the 650cc units. Install the fuel pump voltage booster according to the instructions—this typically splices into the fuel pump control module near the fuel tank. The booster raises voltage from 12V to ~15V under wide-open throttle, ensuring consistent fuel pressure. If you are not comfortable with electrical wiring, this is one area where professional help is strongly recommended; incorrect wiring can lead to fuel pump failure or fire.

Step 5 – ECU Tuning (The Most Critical Step)

With all hardware installed, the final step is to flash the ECU with the provided calibration. This requires the use of the ECUTek cable (sold separately or available as part of an “ECUTek Flash Kit”). The base calibration is designed for 91-octane fuel. Once flashed, start the engine and check for vacuum leaks, coolant leaks, and unusual noises. Allow the car to idle until the engine reaches operating temperature, then perform a careful road test. Monitor fuel trims and boost pressure using a scan tool or a Bluetooth OBD-II adapter with an app like Torque Pro. Boost should peak at 6 psi on the standard pulley.

Power Gains: Dyno-Proven Results

The headline figure of +125 wheel horsepower is not marketing exaggeration—it has been verified on independent dynos by numerous owners. A stock 7-speed automatic G37 typically puts down around 250-260 whp on a Dynojet dyno. With the Stillen supercharger kit and the standard tune on 91-octane fuel, owners see approximately 370-380 whp, representing a 120-130 whp increase. That translates to roughly 440-450 crank horsepower. On 93-octane fuel or with a custom tune optimized for the specific car, some have recorded over 400 whp (around 470 crank hp). The torque curve is transformed: peak torque jumps from around 240 ft-lb to 330-340 ft-lb, with the boost building steadily from 3000 RPM to redline. The power delivery is linear, not the violent kick of a roots-type blower—the centrifugal Vortech feeds boost progressively, making the car feel like a naturally aspirated V8 that just keeps pulling harder as the revs climb.

Here is a typical dyno comparison table (approximate values):

ConfigurationWheel HorsepowerWheel Torque (ft-lb)Crank Equivalent
Stock G37 (7AT)252 whp235 wtq330 hp
Stillen Supercharger (91 octane, base tune)375 whp335 wtq440 hp
Stillen + Full Exhaust + Custom Tune (93 octane)410 whp360 wtq480 hp

These gains are substantial: a 150+ hp increase over stock. In the real world, the G37 becomes genuinely quick. 0-60 times drop from the high 5-second range to the mid 4-second range (in the 4.3-4.5 second bracket with a good launch). Quarter-mile times go from ~13.7-14.0 seconds at 103 mph to 12.2-12.5 seconds at 113-116 mph, depending on traction and tune. For comparison, that puts the supercharged G37 in the same league as a Chevrolet Camaro SS or a BMW M3 (E90) in straight-line performance.

Beyond Horsepower: The Driving Experience

Numbers only tell part of the story. The Stillen supercharger fundamentally changes the way the G37 drives. The stock engine is responsive but can feel a bit flat in the mid-range; the supercharger fills that void with a wave of torque that surges from 3000 rpm to the 7500 rpm redline. The car feels effortlessly fast in everyday driving—merging onto highways, overtaking on two-lane roads, or climbing mountain passes. The air-to-water intercooler keeps intake temperatures well under control even during repeated pulls; logs show IAT (intake air temperature) often staying within 20-30°F above ambient, whereas a poorly designed air-to-air system can suffer from heat soak after one or two hard runs. The supercharger whine is present but subtle—a faint whistle under full throttle that adds character without being obnoxious. At cruise, the system is nearly silent, making the car a comfortable daily driver.

Cost Breakdown and Long-Term Considerations

The $4,500 price tag for the supercharger kit is an entry point. For a complete, trouble-free installation, most owners should budget for additional items:

  • Professional Installation: $1,200 – $2,000 depending on labor rates and whether the shop has experience with this kit. While DIY is possible, a professional ensures the belt alignment, intercooler plumbing, and ECU tuning are correct.
  • ECUTek Cable and Licensing: ~$500-$700 if not already included (check with Stillen; some vendors bundle it).
  • Spark Plugs and Fluids: $100-$150 for NGK spark plugs, coolant, and oil change.
  • Optional Upgrades: Full exhaust system (cat-back, $800-$1,200) to free up more power; a larger crank pulley ($200-$300) for higher boost but requires premium fuel and possibly a custom tune; oil catch can ($150) to reduce blow-by in the intake tract; and a fuel system upgrade (e.g., upgraded in-tank pump, $200) if pushing beyond 400 whp.
  • Custom Dyno Tune: $500-$700 if you wish to have a professional tuner optimize the ECU map for your specific fuel and modifications.

Total cost for a well-sorted supercharged G37 often lands between $7,000 and $9,000, including installation and supporting mods. While that is a significant sum, it is still far cheaper than buying a factory supercar and yields a car that is both unique and highly capable.

Reliability and Maintenance

The VQ37VHR engine is known for its robustness, and the Stillen kit is designed to operate within safe limits. Engine oil should be changed more frequently—every 3,000-4,000 miles with a high-quality full synthetic, as the supercharger places additional heat stress on the oil. Intercooler water should be changed annually or as needed to prevent corrosion. The Vortech supercharger itself requires an oil change every 20,000-30,000 miles (Vortech provides a kit). Belt life is reduced compared to stock; inspect the drive belt every 10,000 miles and replace if frayed. With proper maintenance, many owners have logged 50,000+ miles on their supercharged G37s without major issues. The weak point is the 7-speed automatic transmission (RE7R01A) when subjected to high torque; while it can handle 400 ft-lb with proper transmission fluid maintenance and possibly an upgraded transmission cooler, some owners choose to upgrade to a Level10 valve body or IPTCore built transmission for peace of mind. The manual transmission (6-speed) is more robust and handles the power well with a heavier clutch and flywheel upgrade.

Alternatives and Considerations

While the Stillen kit is the most popular bolt-on supercharger for the G37, there are alternatives. GTM (George T. Marino) offers a twin-turbo kit that can produce similar or higher power, but at a higher cost ($7,000+) and with more complexity. Stillen’s supercharger is also available for the Nissan 370Z, which shares the same engine. Another option is the Stillen Stage 2 kit (discontinued but still available used) that included larger injectors and a high-pressure fuel pump. For the budget-conscious, a nitrous oxide kit (100-125 shot) can provide similar power gains for under $1,000, but with the need to refill bottles and the risk of detonation if not tuned properly.

Before purchasing, check your local regulations: the Stillen kit is CARB exempt for 2009-2013 G37 models only—verify your specific year and VIN. Also, consider the condition of your car: a high-mileage engine (above 100,000 miles) should undergo a compression and leak-down test to ensure it is healthy enough to accept boost without failure.

Real-World Owner Experiences

To provide a balanced perspective, we reached out to several G37 owners who have installed the Stillen supercharger. Here are their insights:

“The car feels completely different. It’s not just faster—it’s more responsive and sounds incredible. I did the install myself over two weekends with a friend. The hardest part was routing the intercooler hoses. But once it was running, I knew it was worth every penny. The only downside is that now I want even more power, so I’ve already started planning a larger pulley and a cat-back exhaust.”
— Mike R., 2012 G37S Coupe, 65,000 miles on supercharger.

“I had a professional shop do the install. It took about 16 hours labor. The tune was fine, but I got a custom dyno tune after adding headers and a full exhaust. Now it makes 415 whp and it’s a riot. The only issue I had was a minor coolant leak from a hose clamp that wasn’t tightened enough. I’d recommend using T-bolt clamps instead of worm-gear ones. Overall, reliability has been great for 30,000 miles.”
— David L., 2010 G37 Sedan, daily driver.

“The biggest mistake people make is skimping on the tune. Don’t run the base map without checking fuel trims—my car ran lean on the base tune on 91 octane. I had to use a different gas station or add octane booster. Once I got a custom tune from a respected Nissan tuner, it has been perfect. Also, upgrade the fuel pump voltage booster—the stock one can drop voltage under load.”
— Tom S., 2013 G37 IPL Convertible (rare, but same engine).

Conclusion: Is the Stillen Supercharger Right for You?

The Stillen Supercharger is not a cheap modification, but it delivers exactly what it promises: a dramatic, reliable, and street-legal increase in power that transforms the Infiniti G37 from a competent grand tourer into a genuine performance car. For enthusiasts who already appreciate the G37’s blend of luxury and handling, adding forced induction takes the experience to a new level. The kit is well-engineered, supported by a strong aftermarket community, and has proven itself over a decade of use.

If you are willing to invest the time and money—both in the kit itself and in proper installation, supporting mods, and maintenance—the Stillen supercharger is arguably the best single upgrade you can make to a G37. The result is a car that can hang with modern muscle cars and European sports sedans, all while retaining the refined interior and comfortable ride that made the G37 popular in the first place. For those seeking the ultimate expression of the VQ37 platform, the Stillen supercharger remains the gold standard.

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