How to Supercharge Your Honda Civic Si (K20 & K24)

A supercharged Honda Civic Si is one of the fastest, most reliable ways to turn the high-revving K-series engine into a genuine 300-wheel-horsepower street car. The KraftWerks Civic Si supercharger kit bolts a Rotrex C30-94 centrifugal blower onto the factory 2.0L K20Z3 (2006-2011) or 2.4L K24Z7 (2012-2015) engine, adding roughly 8-9 psi of boost and, per KraftWerks, gains of up to 64% over stock — all while keeping the car’s daily-driver manners. This guide walks through exactly how to supercharge your Civic Si: the power you can expect, what is in the kit, a step-by-step install overview, K20 vs K24 fitment, and the supporting mods that keep it reliable.

The KraftWerks 06-11 Honda Civic Si supercharger kit, built around the Rotrex C30-94 traction-drive blower.

How Much Power Does a Supercharged Civic Si Make?

A KraftWerks-supercharged Civic Si typically makes around 300 wheel horsepower on the supplied pulley — roughly a 60% increase over a stock car. The 8th-generation Si (2006-2011) leaves the factory rated at 197 hp and 139 lb-ft of crank torque from its 2.0L K20Z3, which usually translates to about 170-180 whp bone-stock. The 9th-generation Si (2012-2015) makes 201-205 hp and 170 lb-ft from the larger 2.4L K24Z7. Bolting on the Rotrex C30-94 at 8-9 psi brings both cars into the 290-310 whp range with the FlashPro calibration, fuel and weather permitting.

Because the Rotrex is a centrifugal supercharger, power builds progressively with engine speed rather than arriving in one turbocharger-style hit. That means the boosted K20 still loves to rev to its 8,000 rpm redline, and the extra torque is delivered smoothly to the front wheels through the factory limited-slip differential. Expect 0-60 mph to drop from roughly 6.5 seconds to the mid-4-second range on a well-hooked-up car.

On the stock pulley the Rotrex spins the K20 to roughly 300 whp while staying easy to daily drive.

What Is in the KraftWerks Civic Si Supercharger Kit?

The KraftWerks kit is a complete, non-intercooled centrifugal supercharger system centered on the Rotrex C30-94. Rotrex uses a patented traction-drive design — power is transmitted through a planetary friction drive rather than gears, letting the impeller spin up to roughly 90,000 rpm with very low noise and vibration. The result is high adiabatic efficiency and cool outlet air temperatures, which is why these kits run reliably at 8-9 psi without an air-to-air intercooler.

Every kit ships with the Rotrex C30-94 supercharger, a CNC-machined mounting bracket, the traction-fluid pump and reservoir, the drive/idler pulley system, a serpentine belt, an air intake, and all necessary hardware. The version we recommend also includes the Hondata FlashPro with a KraftWerks base calibration, so the factory ECU is properly mapped for boost, ignition timing, and fueling before the first start.

The compact Rotrex C30-94 spins to roughly 90,000 rpm and runs far cooler than a comparable roots blower or turbo.

KraftWerks

06-11 Honda Civic Si Supercharger Kit w/ FlashPro

$5,617.95

Part Number	KRT150-05-1331
Fitment	2006-2011 Civic Si (K20Z3), coupe & sedan
Supercharger	Rotrex C30-94 centrifugal

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How to Install the KraftWerks Supercharger (Step by Step)

Installing a KraftWerks Civic Si supercharger is a bolt-on job that takes an experienced DIY mechanic roughly 8-12 hours; no engine removal or internal machining is required. Here is the high-level sequence our shop follows on an 8th-gen K20Z3:

1. Prep and disconnect. Park on a lift or jack stands, disconnect the battery, and drain the coolant. Let the engine cool completely before touching the exhaust manifold area.
2. Remove factory intake parts. Take off the engine cover, air box, intake pipe, and the accessory belt so the crank pulley area is accessible.
3. Mount the bracket. Bolt the KraftWerks CNC bracket to the block using the supplied hardware. This carries the Rotrex C30-94 and its idler pulleys.
4. Install the supercharger and drive. Fit the Rotrex to the bracket, then route the new serpentine belt over the crank, accessories, and blower pulley, and set belt tension.
5. Plumb the traction fluid. Mount the Rotrex oil pump and reservoir, then fill and prime the traction-drive fluid loop — this lubricates the internal friction drive and must be leak-free.
6. Fit the intake and charge piping. Connect the air intake to the supercharger inlet and route the charge pipe to the throttle body, securing every coupler and clamp.
7. Flash the ECU. Plug the Hondata FlashPro into the OBD-II port and load the KraftWerks base map so fueling and timing match the boost.
8. Refill, inspect, and dyno-tune. Refill coolant, check for leaks, verify belt alignment, then finish with a custom dyno tune on your local fuel for the safest, strongest results.

If you are not comfortable setting belt tension or priming a traction-drive loop, have a reputable Honda tuning shop handle the install. A proper base tune plus a custom dyno session is the single most important step for supercharger longevity.

The CNC bracket, idler pulleys, and serpentine belt drive the Rotrex off the factory accessory system.

8th-Gen K20 vs 9th-Gen K24: Which Kit Do You Need?

KraftWerks builds a dedicated kit for each Civic Si generation because the engines and engine bays differ. The 2006-2011 kit fits the 2.0L K20Z3 coupe (FG2) and sedan (FA5), including the 2008 Mugen Si. The 2012-2015 kit fits the 2.4L K24Z7. Both are offered with or without the Hondata FlashPro — the FlashPro-equipped kits are the smart choice, because a supercharger must not be run on the stock tune. Here is how the four options compare:

KraftWerks builds a separate kit for the 9th-gen 2.4L K24Z7 Civic Si (2012-2015).

Supporting Mods and Tuning Tips

At the stock 8-9 psi pulley, the KraftWerks kit is designed to run on the factory fuel system and internals, which is a big part of its appeal. To keep a supercharged Civic Si reliable, focus on the fundamentals first:

• Fuel & tune: Run 91-93 octane and get a custom dyno tune. The included FlashPro base map is a safe starting point, not a final calibration.
• Spark plugs: Step to one heat range colder and set a tighter gap (around 0.028 in) to prevent spark blow-out under boost.
• Clutch: The factory Si clutch can slip near 300 whp; a stage-1 or stage-2 upgrade holds the added torque.
• Cooling & maintenance: Keep the radiator and oil in top shape, and change the Rotrex traction fluid at KraftWerks’ recommended interval.
• Going bigger: A smaller supercharger pulley plus larger injectors and an e85-capable tune can push output well past 350 whp, but that is beyond the base kit’s scope.

With the Rotrex mounted low in the bay, the supercharged K20 keeps a clean, factory-like engine bay.

A complete KraftWerks kit: supercharger, bracket, drive system, oil pump, intake, and hardware.