Owner: Elliott Moran
Dynamometer Model: SP Engineering Dynojet
Cam Installation: Stephen Rhim
Equipped with the naturally aspirated 2.4L KA24DE engine, the '91+ Nissan 240SX is a mid-sub compact sports vehicle with the heart of a truck. Stock for stock, this 155hp engine takes a serious back seat to the 200+hp turbo 2.0L SR20DET of the Japanese Silvia, the engine most U.S. 240SX owners swap to in the first stages of modifying their cars. To prove the worth of thousands of "truck motors" still pounding pavement today, we gathered three aftermarket bolt-on parts rumored to elevate the KA24DE's performance into maybe-I'll-hold-onto-it-for-a-little-while-longer territory. After all, two overhead cams and 2.4L of displacement isn't a bad place to start.
As with any older vehicle, periodic maintenance is crucial to keeping it in good running condition. With over 180K on the odometer, we had our 240SX serviced with a routine inspection of all fluids, and replaced the spark plugs and plug wires before we began our testing. Besides the usual problems you would find on a car that's over 15 years old, including a leaking transmission and worn-out suspension bushings, the vehicle was in good shape.
With the car strapped to the dyno, we made a series of pulls only to discover peak numbers of only 114.6 hp and 124.3 lb-ft of torque, and a rusty hole in the canister of our stock exhaust. In need of a replacement exhaust, we contacted HKS about their recently introduced 75mm cat-back Sport Exhaust, which comes cloaked in a stealthy matte black finish and retails for under $400. With the new exhaust installed, its free-flowing design improved output by a peak 7.0 hp and 7.2 lb-ft of torque over our stocker, with the largest improvements of 13 hp and 14 lb-ft of torque occurring at 3,800 rpm.
AEM Short Ram Intake System
2,000 to 3,500 range: 1.0 to 4.0
3,500 to 5,500 range: 6.0 to 2.0
intake, filter, brackets, clamps, hose, nuts and bolts, instructions, CARB sticker
10- and 12mm socket, 10mm open-end wrench, ratchet, extension, screwdriver, pliers
Offered in three distinct colors (red, blue, and polished aluminum), the AEM Short Ram intake is constructed of mandrel-bent 6061 aluminum tubing attached to a Dryflow filter using a non-woven polyester-based media that does not use oil as part of its filtering medium. AEM claims the design of their Dryflow filters makes them is easier to clean, more durable, and gives them higher filtration efficiency than oiled cotton filters.
When installing the intake, pay close attention to the step-by-step instructions provided with the kit. An incorrect installation or a loose intake clamp will cause the vehicle's MAF sensor to activate "limp mode", and the engine to lose power.
While our peak horsepower and torque numbers showed marginal gains, a close analysis of the dyno graph revealed a significant gain of 10 hp and 9 lb-ft of torque through the midrange, with the largest taking place at 5,200 rpm. The AEM intake increased airflow to our 2.4L engine, delivering a consistent gain of 8 hp and 8 lb-ft of torque from 4,200 rpm to redline.