The Honda S2000 is celebrated for its high-revving F20C/F22C engine and near-perfect 50/50 weight distribution, making it a favorite among driving purists. While naturally aspirated performance is impressive, adding forced induction can unlock substantial gains without sacrificing the engine's characteristic response. The Rotrex supercharger, a centrifugal-type unit, offers a unique power delivery that builds with RPM, blending seamlessly with the S2000's linear powerband. This guide provides a thorough, step-by-step walkthrough for installing a Rotrex supercharger kit on your S2000, including preparation, mechanical work, and post-installation checks. We will cover both the C30-94 and C38-81 kits commonly used on these cars, though specific steps may vary by kit version.

Tools and Materials Needed

Before beginning, gather all necessary tools and components. Having everything on hand prevents delays and ensures a safe workspace.

  • Rotrex supercharger kit (bracket, intercooler or charge pipes, oil cooler if required, belt)
  • Socket set (metric, 8mm–19mm) including shallow and deep sockets
  • Wrenches (combination and ratcheting)
  • Torque wrench (ft-lb and in-lb ranges)
  • Allen keys (hex bits) for bracket bolts
  • Flathead and Phillips screwdrivers
  • Trim removal tools (for bumper and under-tray)
  • Jack and jack stands (low-profile recommended)
  • Coolant (Honda Type 2 or equivalent) for draining/re-filling
  • Rotrex approved supercharger oil (supplied with kit or available separately)
  • Vacuum hose and T-fittings for boost reference line
  • Wire connectors, heat shrink, electrical tape (for oil pressure sensor or boost gauge)
  • Shop rags and drain pan
  • Safety glasses and gloves

Choosing the Right Rotrex Kit

Several Rotrex supercharger kits exist for the S2000, ranging from carb-legal setups to high-horsepower systems. Common options include the Rotrex C30-94 kit (good for 350–400 whp on pump gas) and the larger C38-81 kit (capable of 450+ whp with supporting modifications). Some kits include an intercooler; others use a water-to-air or air-to-air charge cooler. Ensure your kit is designed for your S2000's model year (AP1 vs AP2) as intake manifold and belt routing differ between the F20C and F22C. Consult the kit manufacturer's documentation before proceeding.

Preparation Steps

Workplace and Safety

Park the car on a level surface, engage the parking brake, and place wheel chocks behind the rear tires. Disconnect the negative battery terminal to prevent accidental short circuits or fuel pump activation. If the car has an alarm, note that disconnecting the battery may require resetting the radio presets—write them down.

Fluid Draining

Remove the radiator cap (engine cold) and drain coolant from the radiator drain plug. Depending on your kit's intercooler setup, you may need to remove the entire radiator or fans. If your kit includes an oil cooler for the supercharger, consider draining engine oil as well—it's easier to access the oil filter with the bumper removed.

Front Bumper Removal

Most Rotrex kits require removing the front bumper to access the intercooler, radiator, and belt routing. Remove the fasteners securing the bumper cover (screws in wheel wells, clips under headlights, bolts under the hood). Carefully slide the bumper off, setting it aside on a soft surface to avoid scratching paint. This step also allows you to install a pre-radiator stone guard if desired.

Removing Stock Components

With the front of the car opened up, remove the following factory parts:

  • Engine cover: Unscrew the eight 10mm bolts and lift off.
  • Stock air intake system: Remove the air filter box, intake tube, and resonator. Unplug the mass air flow (MAF) sensor and set it aside—it will be reused.
  • Throttle body: Disconnect the throttle cable (AP1) or electronic connector (AP2). Remove the four 12mm bolts and carefully pull the throttle body off the intake manifold. Use a new gasket upon reassembly.
  • Intake manifold (optional): Some kits require removing the stock intake manifold to install a larger plenum or charge pipes. If your kit uses the stock manifold, skip this. Otherwise, drain coolant from the crossover pipes and unbolt the manifold, noting the location of vacuum lines.

Take this opportunity to inspect the condition of your drive belts and idler pulleys. Replace any worn components to avoid belt slip under boost.

Installing the Rotrex Supercharger

Mounting the Bracket

Position the provided supercharger bracket onto the engine block, aligning with the existing bolt holes. On the F20C, the bracket typically mounts near the alternator and uses three or four bolts. Apply thread locker (Blue Loctite) to the bracket bolts and torque to manufacturer specifications (usually 32–40 ft-lb). Ensure the bracket is flush and does not interfere with the engine mount.

Supercharger Installation

Slide the Rotrex unit onto the bracket studs. Install the supplied pulley onto the supercharger snout—use a pulley puller if necessary to seat it fully. Torque the pulley nut to the spec provided (often 80–90 ft-lb). Attach the supercharger to the bracket with the supplied bolts and torque to 15–20 ft-lb. Connect the supercharger's inlet pipe to the compressor housing and the outlet to the charge tube leading to the intercooler.

Oil Feed and Return Lines

Rotrex superchargers are self-contained with a separate oil system. The kit includes a dedicated oil cooler with lines. Mount the oil cooler in front of the radiator or in the bumper opening. Connect the oil feed line from the supercharger's oil outlet to the cooler, and the return line back to the unit. Do not mix up feed and return—the lines are often different lengths or have markings. Use a proper Rotrex oil fill procedure: fill through the top port while turning the pulley slowly to purge air. Do not overfill; check dipstick on the supercharger if equipped.

Belt Routing and Tensioning

The kit includes a new belt and a belt tensioner bracket. Follow the supplied belt routing diagram carefully; misfiring can shred the belt or damage idlers. Loosen the tensioner adjustment bolt, install the belt over all pulleys, then tighten the tensioner to the specified preload (commonly indicated by a belt deflection of 0.5–0.75 inches under moderate thumb pressure). Double-check that the belt is fully seated and not rubbing against any brackets.

Intercooler and Charge Piping

If your Rotrex kit includes an air-to-air intercooler, mount it securely behind the front bumper using the provided brackets. Connect the charge pipes from the supercharger outlet to the intercooler, then from the intercooler to the throttle body. Use silicone couplers and T-bolt clamps—tighten evenly to avoid boost leaks. Consider adding a blow-off valve (BOV) or recirculation valve if your kit does not include one; Rotrex recommends a vented BOV for large boost spikes.

Reassembling the Engine

Once the supercharger and intercooler are in place, reinstall the removed components in reverse order:

  • Throttle body: Use a new gasket, torque to 15 ft-lb, reconnect cable or electronic connector, and adjust throttle cable slack on AP1 models.
  • Intake manifold (if removed): Torque to 18 ft-lb in a cross pattern.
  • Air intake system: Connect the MAF sensor to the new intake tube. Ensure the filter is securely clamped and positioned in a cold air location.
  • Engine cover: Tighten bolts to 10 ft-lb.
  • Bumper: Reinstall bumper cover, making sure intercooler and oil cooler have adequate airflow clearance.

Electrical and Vacuum Connections

Refer to the kit instructions for any electrical modifications. Common tasks include connecting a boost pressure sensor to the ECU (if tuning via reflash), wiring a wideband O2 sensor, or installing a low-oil-pressure switch for the supercharger. Use heat shrink and solder for permanent connections. Vacuum lines: tap into the intake manifold for the boost reference line (for boost gauge, BOV, or fuel pressure regulator). Use T-fittings and secure with zip ties.

Cooling System Refill

Refill the cooling system with a 50/50 mix of coolant and distilled water. With the radiator cap off, slowly fill until coolant reaches the neck. Squeeze the upper and lower hoses to burp air bubbles. On the S2000, the engine has a bleeder screw on the thermostat housing—open it until coolant streams out, then close. Confirm no leaks, especially at the supercharger coolant fittings if your kit uses water-cooled bearings.

Final Checks Before Starting

Perform these final inspections to avoid damage:

  • Verify all bolts are torqued: bracket, supercharger, throttle body, intercooler mounts.
  • Check belt tension and alignment—should be centered on each pulley.
  • Ensure no wires or hoses are near moving parts (belt, supercharger shaft).
  • Reconnect battery negative terminal.
  • If the kit uses a separate supercharger oil reservoir, check level with the supplied dipstick.
  • Crank the engine with the fuel pump fuse removed (or with the injectors unplugged) for 10–15 seconds to build oil pressure without starting. Reinstall fuse/injectors after.

Testing and Tuning

Start the engine and let it idle. Listen for unusual ticking, grinding, or belt noise. The supercharger should produce a mild whine under load—this is normal. Check for exhaust leaks (common at the manifold) and charge leaks (hissing at couplers). Drive the car gently for the first 20 miles, avoiding full throttle. Monitor oil temperature and supercharger oil temperature if possible. After break-in, perform a full-throttle pull in third gear, logging boost pressure, air-fuel ratio, and ignition timing. Do not exceed 8–10 psi on stock engine internals without proper fuel management.

Tuning is essential for a supercharged S2000. Options include a reflash of the factory ECU (like from Hondata), a standalone ECU (AEM, Haltech), or a piggyback system. Fuel injectors (550cc–750cc) and a Walbro 255lph fuel pump are recommended for anything above 350 whp. Consult a professional tuner with S2000 experience. For additional community support and common pitfalls, check the S2KI Forums Rotrex supercharger section.

Conclusion

Installing a Rotrex supercharger on your Honda S2000 is a rewarding project that dramatically improves acceleration without sacrificiing the car's nimble character. By following this expanded guide, you can avoid typical installation mistakes and ensure a reliable, high-performance setup. With proper tuning and maintenance, your S2000 will provide years of thrilling boosted driving. Always respect the added torque—upgrade cooling, clutch, and differential as needed, and enjoy the newfound power responsibly.