1991 240sx Se Coupe Technical Features And Specifications

The 1991 Nissan 240SX SE Coupe, a now-classic rear-wheel-drive sports coupe, represents a sweet spot in automotive engineering. It's a vehicle that’s both approachable and offers a surprising depth of technical interest, making it an ideal subject for those keen to understand the mechanics beneath the sheet metal. This piece will delve into the key technical features and specifications that defined the 1991 240SX SE Coupe, providing an analytical overview for enthusiasts and amateur engineers alike.

Engine and Drivetrain

At the heart of the 1991 240SX SE Coupe lies the KA24DE engine, a 2.4-liter, naturally aspirated, dual overhead camshaft (DOHC), inline four-cylinder power plant. This engine, while not groundbreaking in its specifications, is renowned for its reliability and potential for modification.

KA24DE Technical Specifications:

Displacement: 2389 cc (145.8 cu in)
Bore x Stroke: 89 mm x 96 mm (3.50 in x 3.78 in)
Compression Ratio: 9.5:1
Fuel System: Electronic Fuel Injection (EFI)
Horsepower: 155 hp (116 kW) @ 5600 rpm
Torque: 160 lb-ft (217 N⋅m) @ 4400 rpm

The KA24DE's DOHC configuration allows for a relatively high rev range and efficient valve control, contributing to its decent power output. The EFI system, controlled by a sophisticated (for its time) engine control unit (ECU), ensures precise fuel delivery for optimal performance and emissions. The cast iron block contributes to the engine's durability, making it a robust platform for aftermarket tuning.

The engine is typically mated to either a 5-speed manual transmission or a 4-speed automatic transmission. The manual transmission is a popular choice among enthusiasts due to its direct feel and contribution to the car's sporty character. Power is then transmitted to the rear wheels via a driveshaft and a limited-slip differential (LSD) on the SE model, improving traction and handling, particularly during spirited driving.

Suspension and Chassis

The 240SX's handling prowess is largely attributed to its sophisticated independent suspension system. The 1991 SE Coupe features a 4-wheel independent suspension comprised of MacPherson struts in the front and a multi-link setup in the rear.

Suspension Components:

Front: MacPherson struts with coil springs and telescopic dampers. Features include lower control arms and a stabilizer bar to control body roll.
Rear: Multi-link suspension with coil springs and telescopic dampers. The multi-link design allows for independent control of various suspension parameters, such as camber, toe, and roll center, leading to improved handling characteristics. A stabilizer bar is also present to minimize body roll.

The multi-link rear suspension is a key element in the 240SX's appeal. Its design allows for optimal wheel control during cornering, maintaining a consistent contact patch with the road surface. This, combined with the car's relatively low weight (around 2700 lbs), results in a nimble and responsive driving experience.

The chassis is a unibody construction, offering a good balance of rigidity and weight. Strategic reinforcement in key areas, such as the suspension mounting points, helps to improve handling and durability. The car also benefits from a relatively wide track, which further enhances stability.

Braking System

The 1991 240SX SE Coupe comes equipped with power-assisted disc brakes on all four wheels. This provides ample stopping power and good brake feel, especially when compared to older cars with drum brakes.

Braking System Details:

Front Brakes: Ventilated disc brakes
Rear Brakes: Solid disc brakes
Assist: Power-assisted

The ventilated front discs are crucial for dissipating heat generated during braking, preventing brake fade during prolonged periods of hard braking. The power-assisted system reduces the effort required to apply the brakes, making it easier to modulate braking force. Some models may be equipped with an optional anti-lock braking system (ABS), further enhancing safety by preventing wheel lockup during emergency braking situations.

Steering System

The 240SX SE Coupe features power-assisted rack-and-pinion steering. This type of steering system offers a direct and responsive feel, contributing to the car's engaging driving experience. The power assist reduces steering effort, particularly at low speeds, making it easier to maneuver in tight spaces.

Steering System Specifications:

Type: Power-assisted rack-and-pinion
Turning Radius: Approximately 31.5 feet

The rack-and-pinion design provides a precise and predictable steering response, allowing the driver to accurately place the car on the road. The power assist is well-tuned, providing enough assistance without feeling overly artificial or disconnected from the road.

Electrical System

The 1991 240SX SE Coupe operates on a standard 12-volt electrical system. The system powers various components, including the engine management system, lights, gauges, and accessories. The car is equipped with an alternator to charge the battery and provide power to the electrical system while the engine is running.

Key Electrical Components:

Battery: 12-volt
Alternator: Provides charging current
ECU: Controls engine functions (fuel injection, ignition timing)

The ECU plays a critical role in the car's performance and emissions. It monitors various engine parameters, such as engine speed, throttle position, and air intake temperature, and adjusts fuel delivery and ignition timing accordingly. The car also features a diagnostic system that can store and retrieve diagnostic trouble codes (DTCs), aiding in troubleshooting electrical and mechanical problems.

Interior and Exterior Features (SE Trim)

The SE trim level of the 1991 240SX Coupe included several enhancements over the base model, both inside and out.

Notable SE Features:

Limited-Slip Differential (LSD): Significantly improves traction.
Upgraded Interior Trim: Higher quality seat fabrics and interior accents.
Alloy Wheels: Distinctive alloy wheel design.
Rear Spoiler: Adds a sporty aesthetic.
Power Windows and Locks: Convenience features for the time.

These features contributed to the SE's appeal as a more premium and performance-oriented version of the 240SX. The LSD, in particular, made a significant difference in handling, especially during spirited driving or on slippery surfaces.

Conclusion

The 1991 Nissan 240SX SE Coupe is more than just a classic sports coupe; it's a testament to well-engineered and balanced design. Its combination of a reliable engine, sophisticated suspension, and engaging driving dynamics has made it a popular choice for enthusiasts for decades. By understanding the technical features and specifications outlined above, we can appreciate the engineering that went into creating this iconic vehicle and its lasting legacy in the automotive world. The car's simple, yet effective, design continues to be a platform for modification and experimentation, making it a favorite among amateur engineers and car enthusiasts looking to learn and improve their skills.