Nissan 240SX - Performance
There is a decent selection of aftermarket parts for the KA24E and KA24DE engines. However, the KA24 is heavy for a 4-cylinder engine because of its iron block. If you install a turbo and other engine performance parts, you will destroy the car�s even weight distribution. You�ll get more power, but you�ll pay for it with reduced handling.
The most popular modification for the 240SX in the US has been swapping in an SR20DET imported from Japan. The SR20DET is lighter and more powerful than the KA engines.
The SR20DET matches the motor mounts found in the US 240SX models so it drops in easily. Also, SR20DETs are usually sold with the entire front clip from the car they were in, which makes it easy to see where everything belongs. Furthermore, there is tons of information on the Internet about performing and troubleshooting these engine swaps that makes the job less intimidating for 240SX newcomers. The SR20DET�s performance and relative ease of installation make it the most popular engine swap for the 240SX.
A much more exotic modification to the 240SX is swapping in one of the Nissan Skyline RB engines (RB20DET, RB25DET, or RB26DETT). Not only are these engines much more expensive and difficult to get your hands on in the US, but they are obviously bigger than the inline 4-cylinder KA and SR engines. Therefore, getting them into a 240SX requires extensive fabrication work. Weight is also an issue. The heavy 6-cylinder engine will make the 240SX front heavy. To install the RB26DETT, for example, and still keep the desirable stock weight distribution, you will need to shave off weight from the front of the car. Consider installing carbon fiber front bodywork and replacing steel parts on the front of the car with aluminum components.
Another engine swap that is worth considering for the 240SX is the VG30DETT used in the Nissan 300ZX. This V6 outputs approximately 300 hp and can handle much higher horsepower on stock internals. The obvious problem is the size (mainly the width) of this engine and its weight. Nonetheless, the VG30DETT can fit into the 240SX engine compartment with small modifications to the wheel wells.
I recommend spending the extra money and getting an entire front clip instead of just the engine when you are performing a swap. You will save yourself a lot of time by not having to search for essential parts that didn�t come with the engine. Later, you can sell the extra parts from the front clip on eBay.
Engine Swap Resources:
Aftermarket air intake systems usually increase performance by lowering the temperature of the air entering the engine (Cold Air Intake). These systems reposition the intake away from engine heat (such as against a fender or the front bumper). Since cold air is denser than hot air, a cold air intake allows a greater amount of air to enter the engine. Cold air intake systems usually feature larger and smoother piping than stock, which improves airflow. In addition, most intake systems come with high-flow air filters.
To maximize the effect of a new intake system, the intake can be mounted behind the front grill or integrated into a hood scoop to create a �ram air� system. In other words, the air will be forced into the engine by the forward motion of the car. Be careful with air intakes mounted behind the front bumper as these systems can easily suck up water when driving in the rain. Water will destroy the engine if it enters the combustion chamber. If you must use an intake system mounted low on the car, get a water guard along with the intake system.
Products - Air Intake:
Aftermarket exhaust systems increase power by providing a less restrictive path for exhaust gasses to exit the engine. There are three major exhaust parts: headers, downpipe, catalytic converter, and cat-back exhaust (includes tubing and muffler). The headers are connected directly to the engine on one side and to a downpipe on the other side. The downpipe is connected to a catalytic converter, which removes environmentally harmful compounds from the exhaust gases. The catalytic converted is connected though sections of tubing to the muffler, which cancels some engine noise and expels the exhaust gases.
Unfortunately, the efficiency of your exhaust system will be limited by the catalytic converter if you ever plan on passing an inspection. Furthermore, if noise is an issue, make sure that you find out the idle and full throttle noise levels of the muffler you will install from the manufacturer. Depending on the original condition of your engine and the modifications you have already done, an aftermarket exhaust system can add 5-25 hp.
Products - Headers:
Products - Downpipe / Catalytic Converter:
Products - Cat-back Exhaust (for all 240SX models):
A turbo or turbo upgrade forces more air into the engine, which creates more power. When adding a turbo, make sure that your engine internals can handle the extra power. Pistons and other critical components may need to be upgraded. You also need to think about cooling when adding a turbo. An intercooler and high performance radiator are essential.
Products - Turbochargers:
The stock cooling system of the 240SX will not be able to cope with significant power increases. Therefore, it is necessary to install cooling upgrades to reduce intake air temperature and minimize engine knocking (detonation of the air/fuel mixture before the spark plug fires). An intercooler is meant to lower the temperature of intake air that passes through a turbocharger. Air passing through a turbocharger heats up because it makes contact with the hot parts of the turbo and because it is compressed by the turbo. An intercooler lowers the temperature of the pressurized air allowing for more power and more reliable performance. Without an intercooler, detonation (or knocking) can become a serious problem if the car is driven aggressively. The hot air will cause the air/fuel mixture to combust before the spark plug ignites it, which leads to power loss.
The water and oil in an engine must also be cooled. A stock radiator will not be able to dissipate the additional head produced by a high-horsepower engine. A larger aluminum radiator is necessary to cool the engine. An oil cooler is necessary if you plan to use the car on the track or drive aggressively. The oil cooler will control the oil temperature during hard driving and minimize the chance of damaging your engine.
Products - Cooling:
Adding a turbocharger to your engine or upgrading your turbocharger is the fastest and easiest way (other than nitrous oxide) to get more power. However, there are many other options for increasing engine output. I have only covered the basics of engine modifications above. If you want serious power from either the KA24 or SR20 engines, you will need to replace internal engine components such as camshafts, pistons, and connecting rods. Not only will these replacements alone give you more power, but also they will allow the engine to take more boost. Companies such as HKS and Greddy produce high quality internal engine components for the 240SX. In addition to reinforcing engine internals for additional power, you will also need to upgrade your fuel system, most importantly the fuel pump, and your electrical system. These areas are often overlooked, but a high-quality electrical fuel pump and voltage control/grounding kit can noticeably improve the reliability and responsiveness of your engine.
As mentioned above, nitrous oxide is another option for increasing power. Nitrous oxide burns hotter than gasoline, which means that it releases more energy during combustion in the engine. It also increases pressure in the combustion chamber because it releases a large amount of oxygen when it burns. As a result, injecting nitrous oxide along with the air/fuel mixture into the combustion chamber gives the engine more power. However, using nitrous oxide excessively will overheat the engine or cause it to break from being unable to cope with the extra power. Therefore, nitrous oxide (just like a turbo) should only be used after the engine is reinforced to hold the extra power. Nitrous Oxide Systems (NOS) and Nitrous Express (NX) are the two major manufacturers of nitrous systems. These systems are relatively easy to install, and the nitrous bottle can be mounted anywhere in the car.
In order to control all of the modifications you have made to your engine, you will need to tune the engine to work effectively with your turbo and other parts. You can do this yourself, but if you are new to tuning, it would be wise to hire a professional to tune the engine for you. It will almost certainly be necessary to buy an aftermarket programmable ECU if you have not already purchased one along with a turbo kit or some other upgrade. The programmable ECU can be used to dial in the ideal engine timing, air/fuel mixture, and boost settings for your car. Also, by programming an aftermarket ECU for your particular application, you can control where in the RPM range your car makes the most power and torque. Finally, make sure you get a quality set of gauges. Oil temperature, oil pressure, water temperature, fuel pressure, boost, and voltage gauges are essentials on a high performance engine. They can help you tune the engine and notify you of malfunctions so that you can avoid engine damage.