Chris Forsberg Competition 240sx Technical Specifications

Chris Forsberg, a name synonymous with professional drifting, has consistently pushed the boundaries of vehicle control and engineering innovation. His Competition 240SX (S13 chassis) is not just a visually stunning machine; it's a meticulously engineered testament to performance, reliability, and the art of controlled chaos. This technical guide delves into the intricate details of Forsberg's drift car, exploring the key modifications and technical specifications that make it a competitive force on the track.

Engine and Drivetrain

At the heart of Forsberg's 240SX lies a potent powerplant, typically a highly modified Nissan VR38DETT, the engine from the Nissan GT-R (R35). This engine choice provides a substantial increase in power and torque compared to the original KA24DE or SR20DET engines often found in 240SXs. The VR38DETT is favored for its robust design and inherent potential for high-horsepower applications.

Engine Modifications:

Bore and Stroke: Often increased to optimize displacement for increased power output. The specifics depend on the tuner and desired performance characteristics.
Forged Internals: Critical for handling the immense pressures and stresses of a high-output, turbocharged engine. Forged pistons, connecting rods, and a crankshaft are essential.
Cylinder Head Work: Porting and polishing the cylinder heads improves airflow, while upgraded valves, valve springs, and retainers allow for higher RPM operation without valve float.
Turbochargers: Typically, twin Garrett turbochargers are utilized, often larger than the stock GT-R units to further boost power. Custom turbo manifolds are almost always employed for optimal flow and placement.
Engine Management System (EMS): A standalone EMS, such as a MoTeC or Haltech system, is crucial for precise control over fuel delivery, ignition timing, and boost pressure. This allows for fine-tuning the engine's performance for specific track conditions and driving styles.
Fuel System: High-flow fuel injectors and fuel pumps are necessary to supply the engine with the required amount of fuel. A surge tank is also commonly used to prevent fuel starvation during extreme G-forces.
Cooling System: An upgraded radiator, oil cooler, and intercooler are essential for managing the increased heat generated by the high-performance engine.

The drivetrain is another crucial area that receives significant attention. The VR38DETT engine is then mated to a robust transmission capable of handling the extreme torque and abuse of drifting.

Drivetrain Specifications:

Transmission: Sequential gearbox, such as a Samsonas or G-Force unit, is often preferred for its speed and precision. These transmissions allow for rapid gear changes without the need for a clutch pedal (except for starting and stopping).
Clutch: A multi-plate clutch is used to handle the high torque output. These clutches are designed to withstand extreme heat and slippage.
Driveshaft: A custom-built driveshaft, typically made from carbon fiber or chromoly steel, is used to transmit power from the transmission to the rear differential.
Rear Differential: A limited-slip differential (LSD) is crucial for drifting. It ensures that power is distributed to both rear wheels, allowing for controlled slides. Different types of LSDs are used, such as clutch-type or spool, depending on driver preference and track conditions.
Axles: Upgraded axles are essential to withstand the high torque and stress of drifting.

Chassis and Suspension

The chassis and suspension are critical for achieving the desired handling characteristics in a drift car. Forsberg's 240SX features extensive modifications to improve rigidity, reduce weight, and optimize suspension geometry.

Chassis Modifications:

Roll Cage: A full roll cage is mandatory for safety in professional drifting. It also significantly increases the chassis rigidity, improving handling and responsiveness.
Seam Welding: Reinforces the chassis by welding along the factory seams, further increasing rigidity.
Lightweight Body Panels: Carbon fiber or fiberglass body panels are often used to reduce weight. This can include the hood, doors, trunk lid, and fenders.
Tubular Front and Rear Ends: Fabricated from chromoly steel, these replace the factory frame rails, offering significant weight savings and allowing for greater suspension adjustability.

Suspension Specifications:

Coilovers: High-quality coilovers, such as those from KW or Fortune Auto, are essential for adjusting ride height, damping, and spring rates.
Adjustable Suspension Arms: Allow for precise adjustments to camber, caster, and toe. These adjustments are crucial for optimizing tire contact patch and achieving the desired handling characteristics.
Modified Knuckles: Often used to increase steering angle, allowing for greater drift control. These knuckles change the steering geometry, allowing the front wheels to turn further.
Sway Bars: Adjustable sway bars are used to fine-tune the handling balance of the car.
Bushings: Upgraded bushings, typically made from polyurethane or Delrin, replace the factory rubber bushings. This improves suspension response and reduces flex.

Brakes and Wheels

Braking performance is paramount, even in drifting, for initiating slides, controlling speed, and making corrections. The wheels and tires are the final link between the car and the track, and their selection is crucial for grip and performance.

Brake System:

Big Brake Kit: Larger rotors and calipers provide increased stopping power and heat dissipation.
Adjustable Brake Proportioning Valve: Allows the driver to fine-tune the brake bias between the front and rear wheels.
Hydraulic Handbrake: Essential for initiating and controlling drifts.
Braided Brake Lines: Improve brake pedal feel and prevent brake fade.

Wheels and Tires:

Wheels: Lightweight wheels, typically made from forged aluminum, are used to reduce unsprung weight. Wheel size and offset are carefully chosen to optimize tire fitment and handling.
Tires: High-performance tires, often with a specific compound and tread pattern designed for drifting, are used. Tire pressure is a critical factor in determining grip and tire wear. Typically, a softer compound is preferred for maximum grip, but wear is a major consideration.

Aerodynamics

Aerodynamics play an increasingly important role in modern drifting. While downforce might not be the primary goal, reducing drag and improving stability at high speeds are crucial.

Aerodynamic Modifications:

Front Splitter: Reduces understeer and improves front-end grip.
Rear Wing: Provides downforce and improves stability at high speeds.
Side Skirts: Reduce drag and improve airflow along the sides of the car.
Diffuser: Helps to smooth airflow under the car and reduce drag.

Electronics and Data Acquisition

Modern drift cars are equipped with sophisticated electronics and data acquisition systems to monitor performance and diagnose problems.

Electronic Systems:

Data Acquisition System: Records data such as engine RPM, speed, throttle position, brake pressure, steering angle, and G-forces. This data can be used to analyze performance and identify areas for improvement.
Sensors: Numerous sensors monitor various parameters, such as engine temperature, oil pressure, and fuel pressure.
Driver Aids: Traction control and stability control systems are typically disabled in drifting, but some teams may use custom-developed driver aids to improve consistency.

Conclusion

Chris Forsberg's Competition 240SX is a prime example of the engineering expertise and dedication required to succeed in professional drifting. From the powerful VR38DETT engine to the meticulously tuned suspension and chassis, every component is carefully selected and optimized for performance. Understanding the technical specifications of this car provides valuable insight into the complex world of motorsports engineering and the constant pursuit of pushing the limits of vehicle performance. It's a testament to the fusion of raw power and calculated control, a machine built to dance on the edge of adhesion.