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Why Supercharge Your S2000 AP2?
The Honda S2000 AP2 is already a beloved sports car, praised for its high-revving F22C1 engine and razor-sharp handling. However, many enthusiasts find that the naturally aspirated power delivery—while intoxicating at high RPMs—leaves something to be desired at lower engine speeds. A supercharger kit, such as the one from Cosworth, addresses this by providing immediate, linear boost across the rev range. Unlike a turbocharger, which can introduce lag, a positive-displacement supercharger like the Cosworth unit delivers instant throttle response. This transforms the AP2 into a car that pulls hard from 3,000 RPM all the way to redline, making daily driving and track work far more rewarding.
The Cosworth supercharger kit is specifically engineered for the S2000 AP2, meaning it bolts on without requiring extensive fabrication. The kit includes a twin-screw supercharger, a cast aluminum intake manifold with integrated bypass valve, high-flow fuel injectors, a reflashed ECU, and all necessary brackets and hardware. The design focuses on maintaining reliability and drivability while giving a substantial power increase. In this guide, we will cover everything you need to know: the installation process in detail, realistic cost breakdowns, tuning requirements, and the performance outcomes you can expect.
Cosworth Supercharger Kit Overview
The heart of the kit is a Type H5220 twin-screw supercharger, a unit known for its efficiency and quiet operation compared to centrifugal blowers. It displaces 1.8 liters per revolution and is designed to produce around 8–10 psi of boost on the AP2’s 2.2-liter engine. The kit also features a water-to-air intercooler integrated into the intake manifold, which keeps intake air temperatures low and consistent. This intercooling system is crucial for preventing knock and allowing safe operation on pump fuel.
Cosworth supplies a custom ECU calibration (either via reflash or an included ECU piggyback module) that adjusts fuel and ignition timing for the increased airflow. The kit is CARB-EO certified (Executive Order D-670-12) in California, making it street-legal in all 50 states—a significant advantage for owners who need to pass emissions inspections. It retains all factory accessories, including air conditioning and power steering, and does not require any cutting or welding of the chassis.
Tools and Preparation Before You Start
Before tackling this project, gather all the necessary tools. While the kit is bolt-on, a few specialized items will make the job easier. You will need a comprehensive socket set (metric), a set of wrenches, a torque wrench (capable of 5–85 lb-ft), a set of pry bars, a coolant flush kit, a vacuum line cutter, and a fluid catch pan. You will also need a floor jack and four jack stands to safely elevate the vehicle.
Additional Supplies
- New OEM intake manifold gasket
- High-quality coolant (Honda Type 2 or equivalent)
- Engine oil and filter (synthetic 10W-30 recommended for supercharged cars)
- Teflon tape for vacuum fittings
- Shop towels and brake cleaner
- A laptop with tuning software (if you plan to data-log during initial startup)
It is also wise to set aside a weekend for the installation. A first-timer can expect 10–15 hours of labor, while an experienced mechanic can finish in 6–8 hours. Ensure your workspace is clean, well-lit, and free of clutter.
Installation Process: Step-by-Step
Step 1: Disconnect and Drain
Start by disconnecting the negative battery terminal. With the car on jack stands, drain the engine coolant from the radiator petcock. Remove the intake air box, throttle body, and entire stock intake manifold. Label all vacuum lines and electrical connectors as you go; taking photos on your phone saves hours of head-scratching later. Remove the stock fuel injectors (you will reuse the injector clips but install the larger injectors supplied in the kit).
Step 2: Install the Supercharger Bracket
The kit includes a heavy-duty aluminum bracket that bolts onto the driver’s side of the engine block. Clean the mounting surfaces on the block with brake cleaner. Apply a thread-locking compound (Loctite 242) to the supplied bolts and torque them to the specification in the instruction manual—typically 18 lb-ft for M8 bolts. The bracket must sit perfectly flush; use a feeler gauge to check for gaps. If the bracket does not seat fully, recheck for dirt or burrs on the mating surfaces.
Step 3: Mount the Supercharger and Intake Manifold
Now comes the most physically demanding part—lifting the supercharger/intercooler assembly into place. This unit weighs about 35 lb. Slide it onto the bracket studs, then tighten the supplied nuts to 35 lb-ft. Do not overtighten. Next, attach the boost bypass valve, which will be connected to the intake piping later. Torque the manifold bolts in a crisscross pattern to the factory specification for the AP2 (21 lb-ft). Ensure the gasket is correctly aligned.
Step 4: Connect Coolant Lines and Intake Piping
The water-to-air intercooler uses engine coolant to reduce intake charge temperature. The kit includes hoses that tap into the heater hose circuit. Use the supplied T-fittings and hose clamps; a leak here will cause overheating or loss of cooling. After connecting the hoses, refill the cooling system with fresh coolant. Next, run the intake piping from the new air filter location to the supercharger inlet. The filter mounts in the stock airbox location—you will need to cut the existing airbox mount slightly, as per the instructions. Secure with silicone couplers and constant-tension clamps.
Step 5: Install the Fuel System Upgrades
Install the larger fuel injectors (310 cc/min, supplied) into the fuel rail. The Cosworth kit uses plug-and-play adapters, so no wiring splicing is required. Reinstall the fuel rail. If your AP2 is an 2006 or later model, you may need to upgrade the fuel pump to a Walbro 255 or equivalent—the factory pump can run out of capacity at higher boost levels. Cosworth recommends this, but it is not included in the base kit. Plan for an additional $150–200 if needed.
Step 6: ECU Calibration
The Cosworth kit comes with a reflashed ECU (or a flash cable for you to reflash the stock ECU). Carefully follow the manufacturer’s instructions for the reflash process. Typically, you need to connect the supplied cable to the OBD-II port and run the software on a laptop. The reflash takes about 15 minutes. Do not skip this step—running the kit without proper calibration can cause detonation and engine damage. After the reflash, reconnect the battery, but do not start the engine yet.
Step 7: Final Checks and First Start
Check all connections: intake hoses, coolant hoses, fuel injector clips, vacuum lines, and throttle cable. Ensure the throttle plate opens fully when the pedal is depressed. Check for any loose bolts or brackets. Refill the cooling system to the proper level. Start the engine and let it idle. Listen for any abnormal noises (belt squeal, boost leaks, etc.). Use a spritz of soapy water on all intake joints to check for bubbles indicating a leak. Let the engine reach operating temperature, then verify the cooling fan cycles on and off. Take the car for a gentle test drive, staying out of boost for the first 10 miles to confirm all systems are stable.
Cost Analysis: Budgeting for Your Build
Total costs vary significantly depending on whether you perform the labor yourself and if you choose additional supporting mods. Below is a realistic breakdown based on current market prices (2025).
| Component / Service | Cost (USD) |
|---|---|
| Cosworth Supercharger Kit (full set) | $5,500 – $6,500 |
| Upgraded fuel pump (Walbro 255) | $150 – $200 |
| Colder spark plugs (NGK BKR7E) | $30 – $50 |
| Coolant, oil, filters, gaskets | $100 – $150 |
| Professional installation (shop labor 8–10 hours) | $800 – $1,500 |
| Dyno tuning (if not using included flash) | $400 – $800 |
| Boost gauge / wideband AFR gauge | $200 – $400 |
| Total (DIY, stock ECU flash) | $6,000 – $7,300 |
| Total (professional install + tune + gauges) | $7,800 – $9,500 |
Note that these are averages. Kit prices fluctuate with supply and demand, and used kits (when available) can save $1,000–$1,500. Labor rates vary by region; expect higher rates in metropolitan areas.
Performance Outcomes: Dyno Results and Driving Impressions
The Cosworth supercharger kit transforms the S2000 AP2. On a dyno, a properly installed and calibrated kit produces approximately 340–360 wheel horsepower (whp) and 220–240 lb-ft of torque, compared to the stock 200–210 whp and 150 lb-ft. That is a gain of 140–160 whp, which equates to roughly 400–420 bhp at the crank (assuming 15% drivetrain loss).
More importantly, the torque curve is drastically flattened. The stock AP2 produces peak torque at 6,500 RPM and falls off quickly. With the supercharger, you have over 200 lb-ft of torque from 3,500 RPM all the way to 8,000 RPM. This makes the car far more tractable on public roads and eliminates the need to constantly downshift to stay in the powerband. On a racetrack, the improved low-end torque allows you to exit corners in a higher gear, reducing shift complexity and lap times by 2–4 seconds on a 2-mile circuit.
Fuel economy does decrease: expect a drop of about 15–20% under normal driving conditions (from ~24 mpg to ~19 mpg). Under hard acceleration, fuel consumption rises dramatically, but that is the price of power.
Reliability Considerations and Longevity
The Cosworth kit is designed to be robust, but forced induction always adds stress to an engine. The AP2’s F22C1 has a forged steel crankshaft and reinforced block, making it capable of handling 400+ bhp reliably—provided the tune is safe. The included flash calibration is conservative, running slightly rich fuel mixtures to keep exhaust gas temperatures down. However, many owners opt for a custom dyno tune to extract every bit of power while maintaining safety margins. If you plan on tracking the car, consider upgrading the radiator to a dual-core unit and installing an oil cooler. The intercooler system works well, but on a 95°F race day, intake temperatures can still climb; a larger intercooler reservoir or auxiliary pump helps.
Common failure points on supercharged S2000s are the fuel pump (if original) and the clutch. The stock clutch cannot hold 340+ whp for long—expect to replace it within 10,000–20,000 miles of hard use. Budget $800–$1,200 for a performance clutch (e.g., ACT HD or Exedy Stage 1). The transmission and differential are durable, though the differential bushings may accelerate wear from increased torque.
Alternatives to the Cosworth Kit
While Cosworth is the premium choice, there are other supercharger kits for the AP2. The SOS Performance centrifugal kit offers higher top-end power (380+ whp) but less low-end torque. The Kraftwerks Rotrex kit is a centrifugal system that is easier to install but requires a standalone ECU for proper tuning. Turbocharger setups (e.g., from Full-Race) can yield over 500 whp but require extensive fabrication and are less streetable. The Cosworth kit strikes the best balance of linear power delivery, CARB compliance, and OEM+ refinement.
Final Thoughts
Installing a Cosworth supercharger kit on your S2000 AP2 is the single most transformative modification you can perform. It addresses the car’s only real flaw—lack of low-end torque—while preserving the high-revving character that makes the S2000 special. With careful installation, proper tuning, and reasonable maintenance, the kit can provide tens of thousands of miles of reliable, exhilarating driving. The costs are significant, but the reward is a sports car that can genuinely compete with modern exotics in straight-line and cornering performance. If you are ready to take your AP2 to the next level, the Cosworth kit is a proven investment.
For further reading, check out the official Cosworth product page for the S2000 AP2 kit here. Community reviews and build threads on S2ki.com also offer invaluable real-world experiences.