Introduction to the Stillen Supercharger Upgrade

Adding forced induction to your Infiniti Q50 with the VR30DDTT engine transforms its personality. The Stillen supercharger kit is a popular choice because it delivers linear, reliable power gains that are fully documented and supported. This upgrade can push your Q50 well past 450 wheel horsepower on a safe tune, dramatically improving throttle response and mid-range torque. While the task is substantial, a methodical approach and proper preparation make it achievable for an experienced home mechanic. This guide expands on every critical phase of the installation, from gathering tools to confirming the final tune.

For reference, the official Stillen kit is designed specifically for the VR30DDTT (found in Q50 and Q60 models). You can review the complete kit contents and specifications on the Stillen product page. Before starting, understand that this is an involved install; budget at least a full weekend and have a second set of hands available for heavy lifting.

Tools and Materials Needed

Having everything organized before you begin prevents frustrating interruptions. The Stillen kit includes most necessary hardware, but you'll need a comprehensive set of shop tools and consumables.

Required Hand Tools

  • Metric socket set (3/8” and 1/2” drive, 8mm through 19mm)
  • Deep well sockets for specific fasteners
  • Combination wrenches (8mm, 10mm, 12mm, 14mm, 17mm, 19mm)
  • Torque wrench (1/2” drive, capable of 20–100 ft-lbs)
  • Ratchet with extensions (3”, 6”, 12”)
  • Swivel sockets or universal joints for hard-to-reach bolts
  • Flathead and Phillips screwdrivers (medium and large)
  • Trim removal tools to avoid breaking plastic clips
  • Pliers (standard, slip-joint, and locking)
  • Pick set for disconnecting hoses and electrical connectors
  • Vacuum hose removal tool (optional but helpful)

Consumables and Fluids

  • Engine coolant (OEM spec – typically Nissan/Infiniti blue or green long-life concentrate)
  • Engine oil (5W-30 full synthetic, about 5.5 quarts with filter change)
  • Thread locker (blue Loctite 242 recommended for critical fasteners)
  • Silicone dielectric grease for electrical connections
  • Shop rags and brake cleaner
  • Safety glasses and mechanic’s gloves
  • Engine support bar or jack stand to cradle the engine when moving components
  • Vacuum leak tester (helpful for checking intercooler and intake connections)
  • Scan tool to monitor coolant temperature and read any trouble codes
  • Professional tuning software or appointment with a dyno tuner (mandatory for final calibration)

For those new to forced induction, consider reading a general overview of supercharger installation basics on Driving Line to understand common pitfalls.

Preparation Steps

Proper preparation reduces errors and keeps you safe. Follow these steps in order.

Vehicle Positioning and Safety

  • Park the Q50 on a level concrete surface. Engage the parking brake and chock the rear wheels.
  • Disconnect the negative battery terminal (12mm bolt). Isolate the cable to prevent accidental contact.
  • Allow the engine to cool completely if it has been running – you'll be working near hot coolant and oil passages.

Engine Bay Preliminary Work

  • Remove the engine cover by pulling upward on the four grommets.
  • Remove the plastic cowl cover (the trim piece spanning the firewall) to access the rear of the intake system. It’s held by push clips and two 10mm bolts.
  • Remove the airbox assembly: disconnect the MAF connectors, loosen the clamps on the intake tubes, and pull the airbox out from its mounts.
  • Carefully detach the vacuum lines attached to the intake tubes – note their routing with labels or photos.
  • Remove the charge air cooler (intercooler) ductwork if your vehicle is equipped with the optional factory unit. This is not required for all Q50 trims, but if present, it must come out.

Stillen recommends draining the engine coolant to allow removal of the thermostat housing and water pump drive belt. Some installers skip this, but it simplifies access. Drain the engine oil as well if you are close to an oil change interval; this prevents spilling oil when removing the oil filter adapter.

  • Place a drain pan under the radiator, open the petcock at the driver-side bottom corner.
  • Loosen the radiator cap after draining to break vacuum.
  • For oil, remove the drain plug (14mm) and oil filter. Replace later with fresh oil.

Removing the Stock Intake System and Front Accessories

With the airbox out, you need to clear the path for the supercharger mounting points.

Remove Factory Intake Manifold

The VR30DDTT uses a plastic intake manifold with integrated charge air cooler. It must come off to access the cylinder head mounting studs where the supercharger bracket attaches.

  • Disconnect the electronic throttle body connectors (two bolts each, 10mm).
  • Remove the bolts holding the manifold to the cylinder heads: there are 10 bolts (8mm socket) plus two hidden under the fuel rail covers.
  • Carefully lift the intake manifold – note the gaskets; they are reusable if undamaged.
  • Cover the open intake ports with clean shop towels to prevent debris entry.

Remove the Drive Belt and Tensioner

  • Use a 15mm socket on the tensioner pulley to relieve belt tension. Remove the serpentine belt and set aside.
  • Remove the tensioner assembly (two 12mm bolts). This creates space for the supercharger drive system.

Prepare the Cylinder Heads for Mounting

  • Clean the mounting surfaces on the cylinder heads with brake cleaner and a lint-free rag.
  • Install the supplied studs from the Stillen kit into the designated M8 holes. Use blue Loctite and torque to 10 ft-lbs using a deep socket.

Installing the Supercharger Bracket and Supercharger Unit

This is the most physically demanding step – the supercharger weighs approximately 35 pounds.

Mount the Bracket

  • Position the cast aluminum bracket onto the passenger side cylinder head, aligning it with the studs.
  • Hand-tighten the supplied flange nuts onto the studs.
  • Secure the bracket to the lower engine block using the provided bolt (14mm). Torque all fasteners to 18 ft-lbs in a crisscross pattern.

Attach the Supercharger

  • With help, lift the supercharger into the engine bay. The snout of the supercharger faces the front of the vehicle.
  • Slide the supercharger onto the bracket aligning the four mounting points. Insert the bolts (M10, 12mm socket) and torque to 30 ft-lbs.
  • Connect the drive pulley: install the supplied drive belt over the supercharger pulley and the crank pulley. Route the belt according to the diagram provided in the Stillen instructions.
  • Reinstall the belt tensioner (the new one may be supplied if the kit includes an upgraded unit). Torque tensioner bolts to 18 ft-lbs.

Secure the Idler Pulley and Belt Routing

  • Verify belt alignment with a straightedge. Misalignment causes premature wear.
  • Rotate the crankshaft pulley (using a 22mm socket on the harmonic balancer bolt) by hand to ensure the belt tracks correctly with no binding.

Connecting the Intercooler and Charge Air System

The Stillen kit includes an air-to-water intercooler that dramatically reduces intake air temperature under boost. Proper sealing is critical.

Install the Intercooler Core

  • Mount the intercooler in the factory location (behind the bumper, in front of the radiator). The kit includes brackets that bolt to the existing crash bar holes.
  • Run the coolant hoses from the intercooler to the supercharger’s water pump (supplied). Secure all hose clamps with a 7mm socket.
  • Open the intercooler coolant reservoir (included) and fill with a 50/50 mix of distilled water and antifreeze. Use only the specified coolant to avoid corrosion.
  • Bleed the system by running the pump at low speed while watching for bubbles in the reservoir. Repeat until no air exits.

Reconnect the Air Intake and Throttle Body

  • Reinstall the factory intake manifold with new gaskets (if the originals are damaged).
  • Reattach the electronic throttle body – clean the sealing surfaces first.
  • Connect the MAF sensors and intake tubes to the supercharger inlet. Ensure all couplers are fully seated and clamps are tightened to 4-5 ft-lbs (do not overtighten the silicone couplers).

Refilling Fluids and Final Mechanical Checks

Before starting, double every connection.

Coolant System Refill

  • Refill the engine coolant through the radiator cap. Use a funnel and fill slowly to avoid air pockets.
  • Run the engine with the heater on full hot to circulate coolant. Top off as needed.
  • Check for leaks at the new intercooler hoses and thermostat housing.

Engine Oil Change

  • Fill with fresh engine oil (5W-30 synthetic) – approximately 5.5 quarts.
  • Start the engine briefly, then turn off and check the dipstick. Add oil as needed.
  • Replace the oil filter with a high-quality unit (OEM or WIX).

Battery and Sensor Reconnection

  • Reconnect the negative battery terminal.
  • Using a scan tool, clear any stored trouble codes from the ECM. This prevents the system from adapting to old fuel trims.

Initial Start-Up and Break-In Procedure

The first start is critical. Follow these steps precisely.

  1. Turn the key to the ON position (engine not started) for 10 seconds to allow the fuel pump to prime.
  2. Start the engine. It may idle high initially as the ECM relearns idle air control (normal).
  3. Listen for unusual sounds: belt squeal, knocking, or air hissing from intake joints. If you hear any, shut down and investigate.
  4. Let the engine reach operating temperature (coolant around 195°F). Watch the temperature gauge – if it climbs above 220°F, shut down and check for coolant leaks or air in the system.
  5. Once warm, turn the engine off and check all fluid levels again. Top off coolant and oil as needed.
  6. Perform a brief test drive (5-10 minutes) with light throttle. Avoid heavy boost until the engine has run for at least 30 minutes total to seat the supercharger bearings and rings.

For detailed break-in recommendations, consult your tuner. Many recommend varying engine speed during the first 100 miles and changing the oil after the first 50 miles to remove any debris.

Testing and Tuning for Performance

Mechanical installation is only half the battle. The VR30DDTT ECU requires recalibration to run safely with forced induction. Running the car without a proper tune can cause detonation and engine failure.

Choosing a Tuning Method

  • **ECU Flash via Cobb AccessPort or EcuTek:** These are the most common solutions for the VR30. You can purchase a pre-loaded tune from a reputable tuner or have a custom tune performed on a dyno.
  • **Remote Tuning:** Many tuners offer e-tuning where you log data on the road and send them files for revision. Ensure you have a reliable wideband O2 sensor reading and boost gauge.
  • **Dyno Tuning:** Ideal for maximizing safe power. A professional tuner can dial in air/fuel ratios, ignition timing, and boost pressure (with the supplied boost controller or pulley options).

Monitoring and Assessment

  • Install a boost gauge (or use the factory’s digital gauges if applicable). Normal supercharger boost is 7-9 psi with the standard pulley.
  • Monitor fuel trims and knock correction using the tuning software or an OBD2 app. Zero knock is the goal.
  • After tuning, verify the car runs smoothly at part throttle and idle.

A good resource for VR30 tuning is the VR30 Performance Forum, where owners share maps and advice. Only use tunes from verified professionals – never run a “generic” map downloaded from an untrusted source.

Common Installation Pitfalls and Troubleshooting

Even with careful work, issues can arise. Here are the most frequent problems and solutions.

  • Belt slip on initial start: Check belt tension and alignment. The tensioner must be set to the correct index mark. If the belt still slips, upgrade to a higher grip belt (Gates Racing or equivalent).
  • Coolant leak at intercooler pump: The pump housing may not seal if the O-ring is pinched. Use a thin film of silicone grease on the O-ring before reassembly.
  • ECU throwing P0101 (MAF circuit) codes: The MAF sensor scaling must match the larger intake piping. This is corrected in the tune. If persistent, check for air leaks post-MAF.
  • Hard starting after installation: Air in the coolant system can cause erratic coolant temp readings, confusing the ECU. Bleed thoroughly.
  • Low boost: Verify the bypass valve is properly connected. A stuck-open bypass valve dumps boost to atmosphere. Also check the boost reference line to the wastegate/internal bypass – it must not be kinked.

Maintenance Considerations After Supercharger Installation

Once the system is running reliably, long-term care ensures longevity.

  • Change supercharger oil per Stillen’s schedule (typically every 60,000 miles or 3 years). Use the supplied oil or equivalent (ISO 46 non-detergent).
  • Inspect drive belt every oil change. Replace at first sign of cracking or glazing.
  • Check intercooler coolant level monthly – top up with distilled water/antifreeze mix.
  • Consider upgrading fuel system components if you plan on pushing beyond 500 whp (larger injectors, high-pressure fuel pump).
  • Keep a log of boost and knock events during the first 1,000 miles. Report any anomalies to your tuner promptly.

For a deeper dive into maintaining forced induction VR30 engines, read this guide on Tuning Technologies.

Conclusion

Installing a Stillen supercharger on your Q50 VR30DDTT is one of the most rewarding upgrades you can do. The process demands mechanical competence, patience, and attention to detail, but the result is a car that delivers thrilling power without sacrificing daily drivability. By following this expanded guide, you can navigate each step with confidence, from pulling the stock intake to dialing in the final tune. Always prioritize safety and proper tuning – a well-executed supercharger installation will provide years of reliable, high-performance driving.