The BorgWarner EFR Turbo Kit: A Game-Changer for the Honda S2000

The Honda S2000 is a modern classic, celebrated for its razor-sharp chassis, near-perfect weight distribution, and the legendary F20C or F22C engine that loves to rev past 9,000 RPM. For many owners, the S2000’s naturally aspirated performance is already thrilling, but there comes a point where only forced induction can unlock the next level of power. Among the various turbocharger options on the market, the BorgWarner EFR (Engineered for Racing) series has earned a dedicated following for its blend of cutting-edge technology, reliability, and real-world drivability. A BorgWarner EFR turbo kit for the S2000 is not just a power adder—it’s a comprehensive upgrade that transforms the car’s character while preserving the feel that makes the S2000 special. This article dives deep into the benefits of choosing an EFR kit for your S2000, covering performance gains, engineering advantages, installation considerations, and the ecosystem of support that comes with this choice.

Substantial and Useable Power Gains

Beyond 300 Wheel Horsepower

The most obvious benefit of adding a BorgWarner EFR turbo kit is the significant increase in power. With the right setup, S2000 engines can reliably produce 350–500 wheel horsepower on pump gas, and even higher numbers with E85 or race fuel. The F-series engines are robust, with forged connecting rods from the factory, making them excellent candidates for moderate boost. A well-matched EFR turbo—such as the 6758 or 7163—can provide a power curve that feels linear and responsive, avoiding the spikey delivery that some older turbo designs suffer from. Dyno charts from shops like Science of Speed and LHT Performance show that a 300–350 wheel horsepower EFR setup delivers strong mid-range torque while maintaining the S2000’s top-end rush.

Torque Delivery That Transforms Daily Driving

While horsepower numbers grab headlines, it’s the torque improvement that makes the S2000 feel genuinely quick from any speed. The BorgWarner EFR’s low-inertia twin-scroll design and ceramic ball bearings allow the turbo to spool quickly, often reaching full boost by 3,500–4,000 RPM. This means you don’t have to hold the engine at 6,000 RPM to get moving. The result is effortless passing power, stronger acceleration out of corners, and a more versatile car that can be driven smoothly in traffic without constantly stirring the gearbox.

Engine Efficiency and Thermal Management

Optimized Air-Fuel Ratio and Combustion

Forced induction naturally increases the density of the intake charge, and the BorgWarner EFR turbo kits are designed to maximize that benefit. The integrated wastegate and internal bypass valve maintain precise boost control, while the billet compressor wheels deliver consistent flow across the operating range. When properly tuned with a capable ECU (such as Haltech, MoTeC, or AEM Infinity), the engine can maintain a stoichiometric air-fuel ratio under cruise conditions and safely enrich under boost. This optimized combustion actually improves thermal efficiency over a naturally aspirated engine operating at the same power level, meaning you can achieve better fuel economy during light throttle driving—a welcome surprise for S2000 owners who daily drive their cars.

Intercooling and Charge Air Temperature

Any turbocharged S2000 requires an effective intercooler to keep intake temperatures in check. EFR kits typically include high-flow front-mount intercoolers with bar-and-plate cores that provide excellent heat rejection. With an EFR setup, even during back-to-back pulls on a hot track day, charge air temperatures stay within reasonable limits, reducing the risk of knock and preserving power. The EFR’s own design incorporates a unique turbine housing that minimizes exhaust gas temperatures at the turbine inlet, helping to keep underhood heat manageable—critical in the tightly packed S2000 engine bay.

Lightweight and Compact: Fits Like a Glove

Weight Savings Over Alternative Systems

The BorgWarner EFR line is known for its remarkably low weight. For example, a complete EFR 6758 turbocharger weighs approximately 14 pounds—significantly less than many comparably sized Garrett or Precision units. When you consider the entire kit (turbo, manifold, wastegate, downpipe, intercooler piping), the total weight added to the car can be less than 40 pounds. In the S2000, which already has a near-perfect 50:50 weight distribution, minimizing the added mass near the front axle is vital for maintaining balance. Many owners report that with an EFR kit, the car’s turn-in response and transient handling feel almost unchanged from the naturally aspirated setup.

Minimal Fitment Issues

Well-engineered BorgWarner EFR kits for the S2000—such as those from Full Blown Motorsports or SOS—are designed with the chassis in mind. The compact turbo housing allows for a tighter manifold layout, often eliminating the need to relocate the alternator or cut into the frame rail. Many kits utilize a top-mount or low-mount configuration that clears the brake master cylinder and hood line with ease. This thoughtful packaging means installation can be completed by an experienced home mechanic in a weekend, without major fabrication work.

Advanced Turbocharger Technology

Twin-Scroll and Integrated Wastegate

The BorgWarner EFR series is at the forefront of turbocharger engineering. Key technologies include twin-scroll turbine housings that separate exhaust pulses from cylinders 1 and 4 versus 2 and 3 on the S2000’s inline-four. This improves scavenging and reduces boost threshold, allowing the turbo to respond like a smaller unit while flowing like a larger one. The integrated wastegate is designed to be leak-free and eliminates the need for external wastegate installation, saving space and cost. Boost control is precise, with minimal creep or oscillation.

Billet Compressor Wheel and Ceramic Ball Bearings

The compressor wheel on an EFR turbo is machined from a solid billet of aluminum, resulting in a perfectly balanced, high-strength part that can spin at extremely high speeds without failure. The wheels feature advanced aero-optimized blade geometry that improves surge margin and efficiency. Coupled with dual ceramic ball bearings (instead of traditional journal bearings), the shaft friction is drastically reduced. This gives the EFR both lightning-fast spool and the ability to tolerate high shaft speeds. In practical terms, the S2000 driver experiences almost no lag on gear changes and can comfortably use lower RPMs for around-town driving.

Gamma-Ti Turbine Wheel

BorgWarner’s gamma-titanium aluminide turbine wheel (used on select EFR models) is a significant advancement over cast steel or Inconel. It reduces rotating inertia by roughly 50% compared to an equivalent Inconel wheel, further lowering spool time while providing excellent durability at high exhaust temperatures. This material choice contributes to the EFR’s legendary quick response and also improves backpressure characteristics, which in turn helps the S2000’s engine breathe more freely on the exhaust side.

Durability and Reliability Under Pressure

Built for Extreme Conditions

The S2000’s engine bay can be punishing for aftermarket parts. Heat soak from the high-revving engine and limited airflow can challenge lesser turbos. BorgWarner EFR units are built to survive. They feature dual water cooling passages and an oil feed that flows directly through the bearing housing, ensuring consistent lubrication even during hot shutdown. The turbine housing is either investment cast stainless steel or high-nickel cast iron, both of which resist corrosion and cracking. Many enthusiasts have logged tens of thousands of street miles and dozens of track days on their EFR turbo kits without any degradation in performance.

Proven in Motorsport Applications

BorgWarner has deep roots in motorsport, supplying turbocharger technology to series like NASCAR, IndyCar, and World Rally Championship. The engineering that goes into these competition units trickles down to the aftermarket EFR line. In the S2000 community, numerous high-profile builds—from time attack cars to street machines—rely on the EFR for consistent performance. This track record gives owners confidence that the turbo can handle extended periods of high boost and high revs without failure.

Customizable Options for Every Build

Choosing the Right EFR Size

Every S2000 owner has different goals. A street-focused driver might prioritize spool and low-end torque, while a track-day warrior wants maximum top-end power. BorgWarner offers EFR turbos in several frame sizes, from the tiny 6258 (great for quick spool on a stock displacement engine) up to the 9180 (for all-out horsepower builds). Most S2000 kits are based on the EFR 6758 (roughly equivalent to a GT3076R), the 7064, or the 7670. Each size delivers a distinct powerband, and reputable kit vendors provide detailed guidance based on your engine spec, fuel, and intended use. Many tuners also offer custom mapping that tailors the boost curve and fuel delivery to the specific EFR model installed.

Supporting Modifications for a Complete Package

An EFR turbo kit is just one piece of the puzzle. To fully exploit the turbo’s potential, S2000 owners typically upgrade the fuel system (larger injectors, higher-flow fuel pump, and a return-style fuel system if running E85), add a larger radiator and oil cooler, and install a capable clutch to handle the increased torque. The beauty of a well-designed kit is that it can be expanded incrementally. Starting with a low-boost setup (6–8 psi) on a stock motor is a popular entry point, and as budget allows, the boost can be turned up after internal engine upgrades (such as forged pistons and rods). The EFR’s wide operating range makes it forgiving of differing power levels.

Community Support and Proven Resources

Forums and Groups Dedicated to Turbo S2000s

The S2000 is one of the most documented platforms in enthusiast history. Forums like S2KI contain years of build threads, dyno graphs, and installation walkthroughs specifically about BorgWarner EFR kits. Owners share everything from preferred boost controller settings to tips for routing intercooler piping around the ABS module. Reddit communities such as r/S2000 also offer more recent real-world experiences. This wealth of collective knowledge makes troubleshooting and fine-tuning much easier than starting from scratch.

Experienced Tuners and Shops

Several tuning specialists have deep experience with EFR-equipped S2000s. Shops like Science of Speed (Arizona), LHT Performance (Florida), and N2F Dyno (California) have developed remote tuning services and calibration files that work with common ECU upgrades. These professionals understand the nuances of the F20/F22 engine—like the importance of maintaining oil supply to the head at high revs and avoiding knock at the top end—and can set up a BorgWarner EFR system to be both powerful and reliable. Joining a community of owners who have already navigated the process saves time and money.

Final Thoughts: Is the BorgWarner EFR Turbo Kit Right for Your S2000?

For S2000 enthusiasts who crave more power without sacrificing the car’s intrinsic balance and rev-happy nature, a BorgWarner EFR turbo kit represents an outstanding investment. The combination of increased power output, improved engine efficiency, lightweight packaging, advanced turbocharger technology, and proven durability makes it a compelling choice. Whether you’re building a street-friendly weekend toy, a daily driver with some extra punch, or a dedicated track weapon, the EFR series offers the flexibility to meet your goals. With the strong aftermarket support network and a thriving owner community, the path to a turbocharged S2000 has never been more accessible. If you’re ready to unlock your car’s full potential, a BorgWarner EFR kit is one of the most thoughtful and rewarding upgrades you can make.