If you've got a 240SX and love to drive, at some point you're going to have to come to grips with the fact that your iron truck engine just isn't going to cut it for serious performance use. The 240SX was originally known as the Silvia, standing today as the Japanese equivalent to Ford's 5.0 Mustang. Lightweight, rear-drive, cheap to buy and modify, the Silvia that hit so big in its homeland lost a bit of its glamor when Nissan dropped the turbocharged SR20DET, installed the KA24 and re-dubbed it the 240SX. The situation is rectifiable, but fixing Nissan's mistake will require some time, money and effort on your part.
Prepare the engine by removing the stock motor mounts and the turbo down-pipe (which will hit the steering column on left-hand drive vehicles). Inspect and replace any sensors and ancillaries that need it. Remove the L-shaped coolant bracket from the back of the turbo and move it slightly toward the passenger side. Attach the U-shaped heater hose to the back of the engine.
Remove the stock KA24 automatic transmission and exhaust system. Remove the interior trim panels from the car, as well as the radio and gauge pod. Remove the driver's seat to make room. Remove the fender liners, front bumper cover and bumper core, power steering pump and lines and A/C compressor. Set the compressor off to one side; do not evacuate the system.
Prepare your SR20DET manual transmission by first removing the shifter linkage, changing the fluids and filters and replacing the old throw-out bearing. Install an SR20DET clutch onto the new motor and consider upgrading to an aftermarket clutch to withstand future power gains. Bolt the transmission onto the engine.
Install a stock Nissan manual transmission clutch and brake pedal assembly; these bolt right into place of the automatic assembly. Cut a hole in the firewall and mount the master cylinder in the engine bay. Remove the steering column's lower cover and unplug the ignition key capture module that locks the key when the transmission is in park.
Mount the SR20DET and transmission. Believe it or not, physically bolting the engine into place is one of the easiest parts of this swap since the 240SX chassis was actually designed with this powertrain in mind and later adapted for the KA24. The new engine goes in at a 45-degree angle and bolts in place of the old one.
Install the intercooler behind the bumper core, the intercooler piping to the turbo and engine and the blow-off valve. Trim the bumper opening to clear the intercooler before reinstalling it. You may need to relocate the windshield wiper reservoir an inch downward to clear the intercooler piping. Relocate the battery to the trunk.
Add an aftermarket exhaust system designed for this swap. If your KA24 was a dual overhead cam model, the power steering pump will bolt onto the SR20DET. If your KA24 was a single cam model, you'll need to buy an SR20DET-specific reservoir and line set. Install the A/C compressor onto the SR20DET with a specialized adapter bracket.
Install an aftermarket electric fan onto the radiator to clear the SR20DET. Install the SR20 wiring harness and ECU (computer) that you purchased with the motor. This is an incredibly complex procedure. Wiring the engine, gauges, chassis systems and fuel system to work together requires an intricate understanding of auto electronics. At the very least, you'll need to purchase an electronics install guide or, better yet, a DVD to get the wiring right.
Upgrade the fuel system with aftermarket injectors, a high-pressure aftermarket fuel pump and higher-capacity lines. Connect the vacuum lines according to your swap guide. Fill the engine with fluids, prime it and check the electrical connections. Attempt to start the engine and prepare yourself for several weekends chasing down electrical gremlins. Don't get too frustrated; it's to be expected with a fuel-injected swap of this complexity.
