Rb20det Engine Swap Technical Specifications For Nissan 240sx
The Nissan 240SX, affectionately known as the S13 or S14 chassis, has earned legendary status in the drifting and tuning communities. While the original KA24DE engine is a capable workhorse, many enthusiasts seek more power and responsiveness. The RB20DET, a 2.0-liter turbocharged inline-six engine from the Nissan Skyline family, is a popular choice for an engine swap due to its relatively compact size, impressive potential, and the cool factor of adding a classic Nissan powerplant to the 240SX.
RB20DET Engine Overview
The RB20DET is a 1998cc (2.0L) inline-six cylinder engine featuring an iron block and aluminum head. It's a DOHC (Dual Overhead Camshaft) design with 24 valves. The engine is turbocharged and intercooled, originally producing around 215 horsepower and 195 lb-ft of torque in stock form. Different versions exist, with varying turbochargers and engine management systems, but the core architecture remains consistent. A key element to remember is that this engine was not originally designed for the 240SX chassis, thus a swap will require mechanical and electrical adaptation.
Key Engine Specifications:
- Displacement: 1998cc (2.0L)
- Configuration: Inline-six cylinder
- Cylinder Head: Aluminum, DOHC, 24 valves
- Block: Cast Iron
- Turbocharger: Garrett T3 or T25 (depending on the specific RB20DET variant)
- Fuel System: Electronic Fuel Injection (EFI)
- Compression Ratio: 8.5:1
- Stock Power Output: Approximately 215 hp
- Stock Torque Output: Approximately 195 lb-ft
The Swap: Mechanical Considerations
The RB20DET swap into a 240SX isn't a simple bolt-in affair. Careful planning and execution are crucial for a successful outcome. Here's a breakdown of the key mechanical aspects:
Engine Mounts:
The KA24DE and RB20DET engines have different mounting points. You will need to acquire or fabricate custom engine mounts specifically designed for this swap. Several aftermarket companies offer pre-made swap kits that include engine mounts, transmission mounts, and other necessary hardware. These kits are highly recommended for simplifying the process and ensuring proper engine placement. When selecting a kit, ensure it's compatible with the specific RB20DET variant you're using. Some mounts might also affect hood clearance, requiring modifications or a different hood.
Transmission:
The RB20DET typically comes mated to a Nissan 5-speed manual transmission (FS5W71C). This transmission can be used in the 240SX, but you'll likely need a custom driveshaft to accommodate the different length. Alternatively, some choose to adapt a stronger transmission like the Nissan Z32 300ZX (Z32) transmission for greater durability, especially if planning to increase power significantly. Adapting a Z32 transmission will require an adapter plate. Always make sure the transmission you choose is able to withstand the output of the engine. The transmission mount may also require modification or replacement to properly support the chosen transmission.
Driveshaft:
As mentioned earlier, a custom driveshaft is almost always necessary. This is because the length of the RB20DET transmission, coupled with the 240SX chassis, will result in a driveshaft length that doesn't match any readily available factory option. The driveshaft needs to be properly measured and fabricated to ensure correct length, balance, and U-joint compatibility. Ignoring this detail can lead to vibrations, premature wear, and even failure.
Cooling System:
The RB20DET's cooling system needs to be adapted to the 240SX chassis. This involves connecting the engine's coolant lines to the 240SX radiator. You may need to modify or replace coolant hoses to achieve a proper fit. A thicker, high-performance radiator is highly recommended to ensure adequate cooling, especially in warmer climates or during spirited driving. Consider using aftermarket electric fans to improve airflow over the radiator, particularly at low speeds. Clearance between the radiator and the engine accessories needs to be checked.
Exhaust System:
The stock RB20DET exhaust manifold and downpipe won't directly bolt into the 240SX exhaust system. You will need a custom downpipe fabricated to connect the turbocharger to the existing or new exhaust system. It’s a good idea to install a larger diameter exhaust system (2.5" to 3") to improve exhaust flow and maximize performance. Pay attention to the routing of the exhaust to avoid clearance issues with the chassis and suspension components. Aftermarket exhaust headers are available and can improve performance compared to the factory manifold.
Fuel System:
The RB20DET requires adequate fuel delivery to operate correctly. The stock KA24DE fuel pump and injectors may not be sufficient, especially if you plan to increase boost or horsepower. It is recommended to upgrade to a higher-flowing fuel pump and injectors capable of supporting the desired power level. A fuel pressure regulator might also be necessary to fine-tune the fuel delivery. Ensure all fuel lines are in good condition and properly connected to prevent leaks. Always use fuel-safe lines.
Intercooler:
The RB20DET is turbocharged and requires an intercooler to cool the compressed air from the turbocharger. A front-mount intercooler (FMIC) is a popular choice for the 240SX, but requires some modifications to the front bumper and possibly the removal of the bumper support. A side-mount intercooler (SMIC) is another option, but may not be as effective at cooling the air as an FMIC. Choose an intercooler that is appropriately sized for the desired power output. Intercooler piping must be secured to avoid rubbing or disconnections under boost. Proper intercooler installation is essential for maintaining consistent performance and preventing engine damage.
The Swap: Electrical Considerations
The electrical integration is arguably the most challenging aspect of the RB20DET swap. The engine wiring harness needs to be adapted to the 240SX chassis wiring. This involves identifying the necessary wires for power, ground, sensors, and gauges, and then connecting them to the corresponding wires in the 240SX wiring harness. It's highly recommended to use a wiring diagram for both the RB20DET and the 240SX to ensure correct connections. Incorrect wiring can lead to engine damage or electrical problems.
Engine Control Unit (ECU):
The RB20DET ECU controls the engine's fuel injection, ignition timing, and other critical functions. You can use the stock RB20DET ECU, but it may need to be remapped or tuned to optimize performance for the 240SX chassis and your specific modifications. Alternatively, you can use an aftermarket standalone ECU, which offers greater flexibility and control over the engine's parameters. Standalone ECUs often require professional tuning to achieve optimal results. When selecting an ECU, ensure it's compatible with the RB20DET and has the features you need, such as boost control, launch control, and data logging.
Wiring Harness:
The RB20DET wiring harness needs to be modified to integrate with the 240SX chassis. This involves splicing and connecting wires for various sensors, injectors, coils, and other components. It's highly recommended to use a wiring harness adapter or a custom-made wiring harness to simplify the process and ensure reliable connections. A properly wired harness is essential for avoiding electrical problems and ensuring the engine runs smoothly. Take the time to properly label all wires before making any connections.
Sensors and Gauges:
The RB20DET uses various sensors to monitor engine parameters, such as coolant temperature, oil pressure, and boost pressure. These sensors need to be properly connected to the 240SX gauges so you can monitor the engine's performance. You may need to use adapters or modify the sensor wiring to ensure compatibility. It's important to accurately monitor these parameters to prevent engine damage. Consider installing aftermarket gauges for more precise readings and additional monitoring capabilities.
Common Wiring Issues:
- Grounding: Ensure all ground connections are clean and secure to prevent electrical noise and voltage drops.
- Power Supply: Provide a stable and adequate power supply to the ECU and other electrical components.
- Sensor Calibration: Calibrate the sensors correctly to ensure accurate readings.
- Wiring Routing: Route the wiring harness carefully to avoid chafing, heat exposure, and other potential hazards.
Final Considerations
Before embarking on an RB20DET swap into your 240SX, carefully consider your budget, skill level, and desired outcome. This is a complex project that requires patience, attention to detail, and a solid understanding of automotive mechanics and electronics. Proper planning and research are essential for a successful swap. Be prepared to encounter unexpected challenges and to spend time troubleshooting any issues that arise. Consider seeking assistance from experienced professionals if you're unsure about any aspect of the swap. When done correctly, an RB20DET swapped 240SX offers a unique blend of classic style and exhilarating performance. Most importantly, remember to take all safety precautions throughout the project. Wear appropriate protective gear and use proper tools. A well-executed swap can transform the driving experience of your 240SX, adding a distinct flavor and a significant boost in performance. Happy wrenching!