Rb26dett Engine Swap Technical Specifications For 240sx

So, you're thinking about swapping an RB26DETT into your 240SX? That's a fantastic project and a serious upgrade in power and performance. It's a popular choice for good reason. But let's be honest, it's not exactly a bolt-in affair. It requires planning, patience, and a good understanding of what's involved. This guide will walk you through some of the key technical aspects, potential problems you might encounter, and offer solutions to help you succeed.

Understanding the RB26DETT and the 240SX Compatibility

The RB26DETT, originally from the Nissan Skyline GT-R, is a legendary 2.6L inline-six, twin-turbo engine. The 240SX (S13 or S14 chassis), on the other hand, came with either a KA24DE or SR20DET engine. The crucial difference is that the RB26 wasn't designed for the 240SX chassis, which means you'll need to address several key areas to make it work:

Engine Mounting: The RB26's engine mounts are completely different.
Drivetrain: The 240SX transmission won't bolt up to the RB26.
Wiring: The RB26's ECU and wiring harness are drastically different.
Fuel System: The RB26 needs more fuel than the stock 240SX fuel pump can provide.
Cooling System: The RB26 generates a significant amount of heat.
Clearance Issues: The RB26 is a larger engine and can create clearance problems with the hood and other components.

Common Problems and Solutions

Problem 1: Engine Mounting

Issue: The RB26 engine mounts don't align with the 240SX chassis.

Solution: You'll need to use aftermarket engine mounts designed specifically for an RB26DETT swap into a 240SX. These mounts typically place the engine slightly further back in the engine bay for better weight distribution and clearance. Several companies offer these mounts, and they range in price depending on the brand and features. Be sure to choose mounts that are known for their quality and durability.

Tip: Polyurethane engine mounts are a popular choice, but they can transmit more vibration into the cabin. Consider using rubber mounts for a more comfortable ride, especially if this is a daily driver.

Problem 2: Transmission Compatibility

Issue: The stock 240SX transmission won't bolt directly to the RB26 engine.

Solution: There are a few options here, each with its own pros and cons:

RB25DET Transmission: This is a common and relatively straightforward option. The RB25DET transmission is a good match for the RB26's power output. You'll need to source an RB25DET transmission, driveshaft, and possibly modify the transmission tunnel slightly for proper fitment.
CD009 Transmission: A popular and robust option from the Nissan 350Z/370Z. This transmission can handle significant power, but requires an adapter plate to mate to the RB26. You'll also need a custom driveshaft. The advantage is the CD009's strength and availability.
RB26 Transmission: The original transmission from the Skyline GT-R. This is the most direct option, but these transmissions are becoming increasingly rare and expensive to source.

Tip: Regardless of the transmission you choose, ensure it's in good working order before installation. Replace the clutch, pressure plate, throw-out bearing, and pilot bushing. It's also wise to inspect the synchros and bearings.

Problem 3: Wiring Harness and ECU

Issue: The RB26's wiring harness and ECU are designed for the Skyline GT-R and won't directly interface with the 240SX's electrical system.

Solution: This is one of the more complex aspects of the swap. There are a few primary methods to tackle this:

Standalone ECU: A standalone ECU, such as a Haltech, AEM, or Link, allows you to completely control the RB26 engine. This offers maximum tunability and flexibility, but requires professional installation and tuning. This is often the best option for maximizing performance. The costs range from $1500-$3000 for the ECU and another $500-$1500 for professional tuning.
Modified RB26 Harness: You can modify the RB26 wiring harness to work with the 240SX chassis. This involves splicing and re-pinning wires to integrate the RB26 ECU with the 240SX's gauges, sensors, and other systems. This requires advanced electrical knowledge and can be time-consuming. Several companies offer pre-modified harnesses for this swap, which can simplify the process considerably.

Tip: No matter which option you choose, thoroughly label all wires and connectors during the removal and installation process. This will save you countless hours of troubleshooting later on. A good wiring diagram is absolutely essential.

Problem 4: Fuel System

Issue: The stock 240SX fuel pump and fuel lines are insufficient for the RB26's fuel demands, especially if you plan to increase the boost.

Solution: You'll need to upgrade the fuel system. This typically involves the following:

Fuel Pump: Replace the stock fuel pump with a high-flow aftermarket pump, such as a Walbro 255 LPH or similar.
Fuel Injectors: Upgrade to larger fuel injectors to provide the necessary fuel volume. Injector size will depend on your power goals. 550cc to 750cc injectors are common for mild to moderately tuned RB26s.
Fuel Pressure Regulator: An adjustable fuel pressure regulator allows you to fine-tune the fuel pressure.
Fuel Lines: Consider upgrading the fuel lines to braided stainless steel lines for increased flow and durability.

Tip: When installing the fuel pump, be sure to replace the fuel filter as well. A clean fuel filter ensures proper fuel flow and protects the injectors from debris.

Problem 5: Cooling System

Issue: The RB26 generates a significant amount of heat, and the stock 240SX radiator may not be adequate to keep it cool, especially under demanding driving conditions.

Solution: Upgrade the cooling system with the following:

Radiator: Install a larger, high-performance aluminum radiator. Many aftermarket radiators are specifically designed for RB26 swaps into 240SXs.
Electric Fans: Replace the stock mechanical fan with electric fans for better cooling efficiency and clearance.
Thermostat: Consider using a lower temperature thermostat to help keep the engine running cooler.
Coolant Hoses: Use high-quality silicone coolant hoses for improved durability and heat resistance.

Tip: Proper bleeding of the cooling system after installation is crucial. Air pockets can cause overheating. Use a coolant bleeding funnel to ensure all air is removed from the system.

Problem 6: Clearance Issues

Issue: The RB26 is a larger engine than the stock 240SX engine, which can lead to clearance problems, particularly with the hood.

Solution: There are a few ways to address clearance issues:

Low-Profile Engine Mounts: Using engine mounts that position the engine lower in the bay can help with hood clearance.
Hood Spacers: Adding hood spacers can provide a small amount of extra clearance.
Aftermarket Hood: An aftermarket hood with a raised center section or a scoop can provide the necessary clearance.
Minor Chassis Modifications: In some cases, you may need to slightly modify the transmission tunnel or other areas of the chassis to ensure proper clearance.

Tip: Before finalizing the engine's position, carefully check the clearance with the hood closed. Pay attention to the turbochargers, intake manifold, and other protruding components.

Tools Needed

Here's a basic list of tools you'll need for an RB26DETT swap into a 240SX:

Basic hand tools (sockets, wrenches, screwdrivers, pliers)
Engine hoist
Engine stand
Welder (for minor modifications)
Angle grinder
Multimeter
Wiring tools (crimpers, strippers, soldering iron)
Drill
Tap and die set
Torque wrench
Fuel pressure tester
Coolant bleeding funnel

Approximate Costs

The cost of an RB26DETT swap can vary significantly depending on the condition of the engine, the quality of the parts used, and whether you do the work yourself or hire a professional. Here's a rough estimate:

RB26DETT Engine (Used): $4,000 - $8,000+
Transmission (RB25DET, CD009): $1,000 - $3,000
Engine Mounts: $200 - $500
Wiring Harness/Standalone ECU: $500 - $3,000+
Fuel System Upgrades: $500 - $1,500
Cooling System Upgrades: $300 - $800
Driveshaft: $300 - $600
Exhaust System: $500 - $1,500
Miscellaneous Parts and Fluids: $500 - $1,000
Labor (if applicable): $2,000 - $5,000+

Total Estimated Cost: $10,000 - $25,000+

Important Considerations: These are just estimates, and the actual cost can be higher or lower depending on your specific situation. It's always a good idea to budget more than you think you'll need to account for unexpected expenses. Remember that a well-executed swap will add value and enjoyment to your 240sx.

In conclusion, swapping an RB26DETT into a 240SX is a challenging but rewarding project. By understanding the technical aspects, addressing potential problems proactively, and using high-quality parts, you can transform your 240SX into a true performance machine. Take your time, do your research, and don't be afraid to ask for help from experienced mechanics or online communities. Good luck with your swap!