So you’ve installed your SR20DET or are about to install it in the 240sx for an upgrade. There are some up things you can upgrade right away for more 240sx power and reliability.
An 80mm(3″) exhaust is a great upgrade for any turbo you might have. The twisted grumble of an exhaust upgrade in 240sx produces intoxicating. A catalytic converter of the same size should be used if there are smog rules/testing in your area. An 80mm downpipe should also be used.
If you are using T2-based turbos that are a straight fit for the SR20DET, then most off-the-shelf downpipes will work.
A low restriction air filter is a great idea for making more power. A cold air intake can also be used with your turbo-charged engine. The colder the air is entering the turbo in the beginning, the cooler the air will be when it gets to the throttle body. A larger intake plenum can also be used as your horsepower requirements go up. This will be necessary to get over 320whp.
A boost controller should be your next upgrade. If you can get an electronic one, you’ll prefer it over a manual one. You can set boost from inside the car. An electronic boost controller will compensate for barometric changes. A manual boost controller is cheap to make or buy and will allow you to raise the boost. But it requires trial runs to set the boost and will change with barometric pressure. All of these changes will result in a fast car.
After these mild upgrades are performed, and many of these are done while the engine is being installed into its new home, some people look for more. A group of modifications should be 555cc injectors, a turbo such as the stock S15 turbo, or similar an ECU upgrade. This will result in about 315rwhp.
The next 240sx upgrade should be cams and intake manifold.
Whether you use the Greddy or Top Speed knockoff, each will offer the airflow capacity at higher RPMs the stock manifold lacks. A 260 or 264 degree cam will move the powerband up, and their higher lift will allow more air into the cylinders to take power to 400whp.
This, of course, means you will need a turbo with the necessary airflow like a GT25R and the like. A lash killer setup is not necessary at this point, but a Rocker Arm Stopper is good insurance. Instead, rebuilding your head because of a rocker arm that became two pieces and ended up somewhere other than where it belonged.
The fastest 240sx are in the 9-second e.t. range. They often use stroked 2.2 liter SR20det. Most 240sx upgrades are done with kits that change the bore to 87mm and the stroke to 90mm. Both torque and horsepower are increased, and a larger turbine may be used with a fast response.