KraftWerks S2000 Supercharger Kit Review: 400 WHP AP2

The KraftWerks S2000 supercharger kit is a bolt-on forced-induction system that pairs a Rotrex C30-94 centrifugal supercharger with a front-mount air-to-air intercooler to nearly double the power of the 2004–2005 Honda S2000 (AP2). Where the naturally aspirated F22C1 leaves the factory with 237 horsepower and 162 lb-ft of torque, this kit is engineered to deliver roughly 400 horsepower to the wheels while retaining air conditioning and every other underhood accessory. At NLP Performance in Tampa, FL, the S2000 remains one of the most-requested platforms for a serious power adder — and after years of building forced-induction Hondas, the KraftWerks Rotrex system is the kit we point AP2 owners to first. This review breaks down the boost, the dyno numbers, what is in the box, and the supporting mods you actually need.

What Is the KraftWerks S2000 Supercharger Kit?

The KraftWerks S2000 supercharger kit (part number 150-05-4004) is a complete centrifugal forced-induction system for the 2004–2005 Honda S2000. At its heart is a Rotrex C30-94 traction-drive supercharger — a compact, ultra-quiet unit that spins its impeller through a sealed traction-fluid planetary drive instead of gears. That design lets the Rotrex spin up to roughly 90,000 rpm smoothly, which is exactly what a high-revving F22C1 wants: linear boost that climbs with engine speed all the way to the 8,000 rpm redline rather than a violent hit down low.

Unlike a positive-displacement (Roots or twin-screw) blower that sits on top of the intake manifold, the belt-driven Rotrex mounts low and compact, feeding a front-mounted air-to-air intercooler through aluminum charge piping. The version we stock is the "without AEM AP2 Tuner" kit, meaning KraftWerks supplies every hard part — supercharger, intercooler, injectors, fuel pump, MAP sensor, brackets, pulleys, tensioner and hardware — but leaves the choice of engine management and tuning up to you. That keeps the price down and lets experienced builders run the standalone or reflash of their choice.

How Much Power Does the KraftWerks S2000 Kit Make?

KraftWerks advertises 400 horsepower and 260 lb-ft of torque to the wheels on the AP2 S2000, and documented dyno pulls have reached 413 whp and 275 lb-ft with the curve climbing steadily to 8,500 rpm. That is a massive jump: a stock 2004–2005 S2000 makes 237 crank horsepower and 162 lb-ft, which typically translates to roughly 200–210 whp on most chassis dynos. In other words, the Rotrex kit adds on the order of 175–200 wheel horsepower — nearly doubling the car’s output while preserving the F22C1’s signature top-end scream.

The street pulley runs roughly 8 psi of boost, and KraftWerks offers a higher-boost pulley (approaching 9–10 psi) for owners running higher-octane fuel and a conservative, well-supported tune. Because the Rotrex is a centrifugal supercharger, boost builds progressively with rpm rather than slamming in at idle — the car still feels like a naturally aspirated Honda off the line, then pulls like a freight train from 5,000 rpm up. That linear delivery is a big reason the kit is so drivable as a daily setup.

Why a Rotrex Centrifugal Instead of a Turbo or Roots Blower?

A centrifugal supercharger like the Rotrex splits the difference between a turbocharger and a Roots-style blower. Compared with a turbo, it has no exhaust-driven lag and no hot exhaust plumbing crowding the S2000’s tight engine bay — boost is directly tied to engine rpm, so throttle response is instant and predictable. Compared with a Roots or twin-screw blower, the Rotrex generates far less heat, spins more efficiently at high rpm, and does not choke the top end — ideal for an engine that lives above 6,000 rpm.

The traction-drive design is the Rotrex’s party trick. Instead of noisy step-up gears, power is transferred through a set of rollers riding on a specialized traction fluid, which is why these units are so quiet and smooth. The trade-off is that the fluid needs periodic service, and the drive belt is a wear item — a fresh KraftWerks supercharger replacement belt is cheap insurance to keep on the shelf.

What Is in the Box — and What Else You Need

The KraftWerks kit is genuinely complete on the hardware side: Rotrex C30-94 supercharger, front-mount air-to-air intercooler with aluminum plumbing, upgraded fuel injectors, a high-flow fuel pump, MAP sensor, and all the brackets, pulleys, tensioners and hardware needed to mount it. What it does not include is a tuning solution, and a few supporting upgrades will make a boosted AP2 far more reliable. Here is how we spec a supercharged S2000 build at our Tampa shop.

Fueling: Injectors and a High-Flow Pump

Once you add 8 psi of boost, the factory fuel system runs out of headroom fast. We spec the DeatschWerks 2200cc injectors because they support well past 400 whp on pump gas and leave room for E85 if you go that route. Pair them with the DeatschWerks 320 LPH in-tank pump to keep rail pressure stable at high load. Under-fueling a supercharged engine is the fastest way to a lean condition and a melted piston — this is not the place to cut corners.

Cooling and Drivetrain: Oil Temps and a Lighter Flywheel

The S2000 is famously hard on oil temperature even in stock form, and forced induction only adds heat. The Mishimoto thermostatic oil cooler keeps oil in the safe zone during track sessions and hard street pulls, with a thermostat that prevents overcooling on cold mornings. On the drivetrain side, a Fidanza 8lb aluminum flywheel drops rotating mass, sharpens throttle response and helps the Rotrex spin up quickly — a favorite pairing with a boosted F22C1.

Exhaust and Chassis

A free-flowing cat-back helps the supercharged engine breathe on the exhaust side. The HKS Hi-Power cat-back is a proven, lightweight choice that adds a purposeful tone without excessive drone. If you plan to use the extra 200 horsepower on a canyon road or track day, upgrading the chassis matters too — a set of Ohlins Road & Track coilovers transforms how the AP2 puts that power down.

Installation, Tuning and Reliability

Installing the KraftWerks kit is a full weekend job for an experienced DIYer and typically a full day of shop labor for a professional. The supercharger, intercooler and charge piping all bolt to factory locations, and because the kit retains the A/C compressor and accessories, there is no permanent modification to the car’s core systems. The critical step is tuning: since this is the "without AEM AP2 Tuner" version, you must supply engine management — a standalone such as the AEM Infinity, a Hondata-based solution, or a comparable system — and have the car tuned on a dyno before it sees boost under load.

Reliability on the F22C1 is strong at this power level when the fundamentals are right: fresh spark plugs gapped for boost, quality fuel, healthy compression and a conservative air/fuel ratio. The stock connecting rods and pistons have proven durable around 350–400 whp on many builds, but the engine’s health and the quality of the tune matter far more than any single part. Keep oil temperatures in check, service the Rotrex traction fluid on schedule, and inspect the drive belt during routine maintenance.