Six-Hour Engine Swap

You can swap in an SR20DET engine into any 1989-1998 Nissan 240SX. This particular car is a 1991 SE coupe.

KA24DE Engine Removal Disconnect the battery. Unbolt the hood from its hinges and rest it carefully on the roof of the car. Unplug the MAF sensor connector. Remove the complete air filter and intake (this 240SX already had an HKS Power Flow installed).

Unbolt the upper radiator supports. This should allow access to the charcoal canister. Remove the canister, bracket, and associated hoses. Unhook the throttle cable. Depressurize the fuel system and disconnect the fuel lines from the engine.

Drain all of the coolant from the engine and the radiator. The radiator fan shroud is connected by clips; remove the shroud. Disconnect the radiator hoses and heater hoses. Unplug the auxiliary fan plug. Pull out the radiator and auxiliary fan.

Inside the car, remove the upper shifter console and the rubber boot. Undo the C clip. Pull out the shifter assembly from the transmission.

Remove the carpet in the passenger footwell. Locate the ECU. Carefully unhook the ECU from the wiring harness.

Pull the wiring harness through the firewall and into the engine bay. Be very careful when you do this. Unhook all related wiring on the passenger side of the engine bay. Snake the harness behind the brake lines mounted on the firewall.

Remove the two 10mm bolts holding down the EGR box. Cut the lower hoses and pull out the box. This will be easier than trying to remove the EGR connection on the exhaust manifold. Remember, this featured car is not street-legal. Removing and damaging emissions control equipment is a big no-no in the eyes of the government.

Raise the car. Locate the transmission drain plug. Remove it and safely dispose of the transmission oil. Remove the clutch slave cylinder by taking out the two 14mm bolts. Take a break; think of how cool you will be when this swap is finished.

Disconnect the downpipe from the catalytic converter. Remove the exhaust bracket for the downpipe. Use a 14mm socket and a long extension to remove the downpipe from the exhaust manifold. Pull out the downpipe.

Locate the speed sensor on the transmission case. Disconnect the sensor&8217s electrical plug and remove it from the tranny by unbolting its 10mm bolt.

Remove the driveshaft bracket and its two bolts. Also remove the four 17mm bolts for the rear transmission mount and take off the mount.

There are two engine mounts. Use a 14mm socket and a long extension to remove the single bolt for each engine mount. With slack now in the driveline, have your friends help you pull the driveshaft away from the transmission.

If your 240SX has air conditioning, you’ll have to disconnect the pressurized refrigerant lines from the AC compressor. You might want a professional shop to do this beforehand--it&8217s against the law to release ozone-depleting R-12 AC refrigerant directly into the atmosphere. Remove the alternator electrical harness. Disconnect the power steering lines.

Connect an engine hoist to the KA engine. Make sure the chain is secure. Slowly raise the engine out of the car. It will take patience to get the engine to clear the bay. Use a floor jack to help the transmission clear the steering rack.

SR20DET Prep Make sure the SR engine is in good condition. Check all major components and replace them, if necessary. Check the mechanical timing. Perform a compression test. Basically, do everything now, since it is the easiest to work on the engine while it is outside the car.

Pull the KA alternator and starter wiring off the old engine. Install it onto the SR engine. Since V-Spec uses a custom engine wiring harness, it was installed at this point. Install the KA engine mounts to the SR engine.

Block off the coolant line for the SR engine. You need to do this because the Silvia is right-hand drive, and the coolant lines are reversed. For the same reason, modify the heater hose hard lines on the SR engine to match the 240SX body.

Replace the SR transmission speed sensor with the KA speed sensor. You need to do this because the SR speed sensor reads in kilometers (duh!). Given that this is a race car, V-Spec plugged up the EGR fitting on the manifold.

SR20DET Install Hook up the SR20DET engine and tranny to the engine hoist. Lower the combo into the engine bay. It will be useful to have some friends help you guide the engine and tranny in. Be patient and careful. It will go in eventually--just like sex.

Replace the clutch slave cylinder with the KA slave cylinder. The SR cylinders tend to dry out because the fluid line is cut when the engine is shipped from Japan.

Connect the driveshaft to the rear of the transmission. Install the driveshaft bracket and the rear tranny mount. Have your friends on-hand to help you line everything up. Bolt the engine mounts to the frame (as before, two mounts).

The turbo should already be installed on the engine. Connect the turbo elbow joint to the turbo exhaust housing (five 13mm bolts). Bolt the turbo downpipe to the elbow joint (three 14mm bolts) and then to the cat. Use the proper gaskets.

Connect the power steering lines and reservoir. The AC was not reconnected on this car. Bend the throttle cable bracket on the throttle body to accept the KA cable. Install and tighten the drive belts.

Remove the heater hoses from the firewall and reroute the new hoses to the modified hard lines on the SR engine. Because of the tight space between the firewall and the engine, this can be very frustrating.

Connect all the proper plugs and connections for the engine wiring harness, such as the injectors, the O2 sensor, and the TPS sensor. Reroute the wiring harness back through the firewall and into the passenger compartment.

Peel back the driver-side plastic inner fender. Locate the factory resonator box. Remove the box by taking out the three 14mm bolts. Enlarge the resonator hole in the frame by using a saw. This is needed to make room for the intercooler piping.

Mount the SR intercooler into the position previously occupied by the resonator. It should bolt right up without your having to drill any holes.

Fill up the transmission with transmission fluid. You can fill it up using the designated plug on the tranny case or the open shifter hole inside the car (Just don&8217t spill any!). After filling the tranny, reinstall the shifter and console.

Install a larger electric fan (get it from an auto parts store) on the radiator. Remove the factory SR crank-mounted fan (V-Spec says it&8217s not needed and saps horsepower). Install the radiator and hoses.

Connect the intercooler pipes to the turbo, intercooler, and the throttle body. Install the MAF sensor housing, intake pipe, and air filter. This car was fitted with an HKS filter and blow-off valve.

Connect the fuel lines to the fuel rail. Hook up the fuel regulator and route the proper vacuum lines. Install the new SR ECU. Fill the engine with coolant and oil. Prime the turbo with oil. Double-check to make sure everything is installed properly.

Mission complete. This is what the installed SR20DET should look like. Be prepared to troubleshoot. For example, the SR here wouldn’t start. Then it would crank, but it wouldn’t fire. After a few minutes of diagnosis, V-Spec traced the problems to a couple of easily fixed minor wiring goofs.

Psst. Hey, buddy. Come over here. I hear you’re looking for some serious turbocharged rear-wheel-drive performance, but you can’t afford a 1990s Supra, RX-7, or 300ZX. Well, I’ve got something for you. Check it out: a Nissan Silvia. Yep, 200-plus horsepower in a 2,700-pound car.

Now, I know what you’re saying: Silvia? You can’t buy that here. Well, it’s true, you can’t. But you can buy the Silvia’s brother, the Nissan 240SX. Give it a bit of heart surgery and bang!--instant Silvia. Just add gas.

Confused? The Silvia and the 240SX are effectively the same car. The main difference is with the engines: The Japan-market Silvia gets a 2.0L turbocharged engine (referred to as an SR20DET engine) while the U.S.-market 240SX gets a 2.4L normally aspirated engine (referred to as a KA24DE engine). Now I’m sure Nissan has reasons why the turbo engine was never offered here, but the bottom line is a stock 240SX eats a Silvia’s dust to the tune of about 50 hp. And in terms of tuning potential, the SR20DET lords over the KA24DE engine like Mark McGwire at a Microsoft company softball game. So, all you gotta do is take the KA engine out of a 240 and put in an SR engine to make it a Silvia, right? Almost.

The biggest challenge to overcome is with the electronics. It&8217s not a simple matter of just installing an SR20DET engine and its respective ECU. The KA24 has a distributor; the SR20DET uses a distributorless ignition system. As such, some of the wiring on the harness is incompatible with the car harness and the ECU. There are two ways around this: Modify the 240SX ECU to work with the SR20DET engine or use the SR20DET engine, SR20DET ECU, and a special engine wiring harness.

I’ve got these pals who can do the swap for ya. They run V-Spec, a small shop in City of Industry, California. The shop has done more than 20 swaps, including the one seen here. The price for the conversion, including the engine, is around $5,000. So, if you go out and buy a $4,000 used 1991 240SX and take it to V-Spec, you’ve got a $9,000 Silvia in America!

Now, don’t go running off to sell your younger brother’s Furbie collection just yet. V-Spec highly recommends consulting your state’s laws concerning engine swaps--swapping in an SR20DET engine into your 240SX might not be legal. It also might not pass smog tests. The swap featured in this story is for a dedicated race car. Therefore, little attention was paid to emissions or legality.

If you are planning to swap an SR20DET into your 240 using nothing more than this article and your $24.95 Wal-Mart "Little Buddy" tool kit, I’d say, well, I’d say you best lay off the hard stuff. Due to space limitations, this story is not an exquisitely detailed how-to on an SR20DET swap. Rather, it is a guide, helping to show the basics.

The minimum items you’ll need include a shop manual, an engine hoist, a floor jack, jackstands, an effective complement of standard hand tools, and a couple of friends. Be prepared to make runs to the parts store to purchase a variety of miscellaneous items like hoses, clamps, and hardware. Oh, a hydraulic lift is real nice, too. With three guys wrenching at the same time, the experienced V-Spec crew completed this swap (from car roll-in to SR20DET fire-up) in six hours! Don’t worry if your swap takes a bit longer.