Starting off with an Edelbrock universal EFI wet nitrous system as the core unit for the 240SX; we tested a grouping of 30, 40 and 50 hp jet settings to see how the vehicle would respond. "Wet" systems use a direct-port style nozzle to introduce nitrous and fuel into the intake runner. Along with the additional stainless steel jets, we called Edelbrock to request additional parts that were vital to the experiment we were about to conduct. Separate from the universal kit, we installed a boost pressure deactivation switch to the intake charge pipe, directly adjacent to the nitrous nozzle. This pressure switch, which is adjustable from 3 to 25 PSI, plays an important role in our drift kit as it disengages the nitrous system once the turbo has achieved a set boost pressure level. Factory pre-set at 7 PSI, the switch is ideal for hardcore racing applications to prevent wheel spin, over-boost and engine damage. In our case, we were looking to shut the nitrous off at approximately 4500-5000rpm and have the turbo boost take over from there. Using the knowledge we gained after a series of dyno pulls, the switch was dialed in at 20psi to keep from prematurely shutting off before the nitrous was activated. One other key component installed on the 240SX was the new Edelbrock Digital Window Switch. Compatible with vehicles ranging from 4 cylinders to 8, the window switch is a simple-to-use unit that controls both nitrous activation and deactivation and is programmable at 100rpm increments. Because we were using the pressure switch as a main source of disengagement, the window switch was triggered to activate at 3000rpm at full throttle and was used as added insurance when deactivating at 5000 rpm in case of over revving or wheel spin, a common occurrence within drifting. Sound like nitrous system overkill for the average consumer? Perhaps, but for a drifter, this adds the distinct advantage of being able to keep the pedal to the floor while one hand mans the steering wheel and the other manages the e-brake- all without the inconvenience of having to press a button to activate the nitrous.
TestingAs we finally began our testing phase, the first task was to record baseline numbers from the pink machine. Modifications to the 240SX prior to the dyno include mild headwork, a Tomei bumpstick and valve springs, custom tubular exhaust manifold, HKS GT-RS turbine, and Power FC tuned by XS Engineering of Huntington Beach, California. Note to all you readers that the bottom end remains stock. Strapped to the dyno, the 240SX boasted a peak of 370.9 wheel hp at 6668 rpm and 315.9 lb-ft of torque at 5394 rpm, set at 1.5 bar of boost. Numerous pulls were extrapolated from the 240SX, and with every pull, the turbo lag was clearly visible on the dyno as full boost was achieved at a less-than-ideal 4500 rpm.
30hp Nitrous Jet TestingInstalling the nitrous kit is a painless process that will take your average Joe anywhere from a few hours to half a day. With the nitrous kit installation near completion, we spent a few minutes bending and mounting the WOT (wide open throttle) switch to bolt up to the throttle body. Installing the 30 hp nitrous and fuel jets was even quicker. A simple turn of the wrench popped those bad boys on the nitrous nozzle and in seconds, we were ready to make our initial nitrous pull. Before any of our runs were conducted, we shot off a couple rounds of nitrous using the optional purge system that was installed inline with the nitrous kit. While many think a purge is strictly show material, it does have its benefits. Using a purge system keeps the supply of fresh liquid nitrous at the solenoid(s) for instant and repeatable nitrous injection while bleeding accumulated nitrous vapor out from the supply lines. Dyno numbers showed that at 3150 rpm, the nitrous begins to work its magic. By 3500 rpm, 23.4 wheel hp and 32.8 lb-ft of torque was gained over baseline. At 4000 rpm, the dyno showed a gain of 42.9 wheel hp and 56.7 lb-ft of torque. More importantly, you'd notice the graph has shifted dramatically to the left, which can aid most lag induced vehicles with increased engine response and added bottom end power, which serves well on our drift vehicle. By the time the vehicle hits 4500 rpm, an increase of 31.6 wheel hp and 33.5 lb-ft of torque was achieved before the nitrous slowly begins to taper off at 5600 rpm and the turbo takes over. Notice a slight gain in top end horsepower? Not only does the nitrous multiply horsepower gains at lower rpm's, but the blast from the initial nitrous became an added bonus for the SR20DET as the chilled liquid injecting into the engine at -127 degrees Fahrenheit added a cooling effect. The denser intake charge benefited in reducing "turbo lag" and managed to extract a few more ponies at higher rpm's well after the nitrous was deactivated.