1996 Nissan 240SX SE - Power Pages

The dyno doesn't lie.

Text By , Photography by Staff

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

intake, filter, brackets, clamps, hose, nuts and bolts, instructions, CARB sticker

10- and 12mm socket, 10mm open-end wrench, ratchet, extension, screwdriver, pliers

Installation Time
50 minutes

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.

DC Sports 4-2-1 Race Header

header, instructions, brackets, sticker, gaskets, mounting hardware

10-, 12-, 14-, 17-, and 19mm sockets, 12-, 14-, 17-, and 22mm open-end wrenches, 7/8-, 15/16-inch open end wrenches, ratchet, extension, crescent wrench, WD-40

Installation Time
120 minutes

The DC Sports 4-2-1 one-piece race header enables exhaust pulses to increase scavenging for additional horsepower in mid-range to top-end engine performance. Lighter than the factory cast-iron manifold, the DC header is manufactured using T409 stainless-steel alloy, robotic TIG welding, and is finished in a corrosion-resistant ceramic coating.

Because the DC Sports long-tube-style header is a cat-delete unit, it's labeled for off-road use only. Removing the factory header from a 15-year-old vehicle can become painstaking, as many of the nuts and bolts are rusted and difficult to remove. Be sure to use the proper tools and plenty of lubricant when removing each bolt.

The new header delivered impressive hp and torque across the board, with a gain of 7.0 hp and 9.6 lb-ft of torque at peak performance. The dyno also recorded impressive mid-range gains: 8 hp and 9 lb-ft of torque at 4,200 rpm.

'91 240SX Exhaust Camshaft


ratchet, extension, 10-, 12- , 14- and 17mm sockets, 10- , 12-, 14- and 17mm open-end wrenches, screwdriver, torque wrench, safety wire (used to secure chain tensioner), crescent wrench

Installation Time
160 minutes

Cheap, easy to find, and an alternative solution to purchasing aftermarket cams for the KA24DE, swapping Nissan S13 KA24DE cams into S14 KA24DE engines has been a popular upgrade for the past few years. Swapping a factory S13 KA24DE exhaust camshaft in place of the intake camshaft of an S14 KA24DE is rumored to be the best bang-for-the-buck power improvement for these engines-we tracked down our cam for $50.

S13 240SX KA24DEs run an intake cam with a duration of 240 degrees and an exhaust cam with a duration of 248 degrees. S14 KA24DE camshafts are rated at 232 degrees of duration for both intake and exhaust. Since duration is how many degrees of crankshaft rotation the valves stay open, the larger S13 exhaust camshaft-identified with an orange stripe from the factory-allows more clean air to enter combustion for more power.

Camshaft installation should be handled by an experienced mechanic to eliminate the chance of valvetrain damage. Depending on the mileage and condition of your engine, we recommend inspecting and properly re-adjusting the camshaft shims and buckets upon reinstallation, or replacing them with upgraded equipment if they're past their prime.

Nissan enthusiasts claiming to have tested the 248/232 cam combination report that it sacrifices a bit of top-end power, but delivers significant gains in the low- to midrange. Our testing revealed the opposite-the new cam didn't increase low/mid output, but did open up the KA's power band at high rpm, particularly above 5,500 rpm, where the stock combination fell off sharply.

At 2,400 rpm, the new cam made an additional 3 hp and 5 lb-ft of torque over our previous run before dropping output by about 6 hp and 8 lb-ft of torque throughout the midrange. At 6,400 rpm, the 248/232 combination made as much as 9 additional hp and 12 lb-ft of torque. But purchasing a set of adjustable cam gears to properly degree the camshafts could have recovered some low/mid power loss, we speculate.

As it sits with stock cam gears, this camshaft combination would be an excellent upgrade for turbocharged KA applications that require the engine to rev high to take advantage of top-end power.


HP Level +HP TQ Level +TQ
BASELINE 121.6 131.4
AEM INTAKE 125.3 3.7 132.9 1.5
DC SPORTS 4-2-1 CERAMIC HEADER 132.3 7.0 142.5 9.6
'91 240SX (S13) EXHAUST CAMSHAFT 135.6 3.3 136.7 -5.8
FINAL 135.6 14.0 136.7 5.3

Conclusion What began as a baseline dyno run of 121.6 hp and 131.4 lb-ft of torque was revamped with a gain of 14.0 whp and 5.3 lb-ft of torque. Although we lost midrange power and torque with our cam-shaft, we suspect some additional tuning could find gains all around. Still, representing a 10-percent jump in horsepower for under a grand (more than 15 percent factoring in the HKS exhaust), our final horsepower gains were solid for any naturally aspirated inline-four, especially the stump-pulling KA24DE.

'91 240SX (S13) EXHAUST CAMSHAFT $50.00
MSRP TOTAL $725.04
P.O. Box 1312
CA  90250
SP Engineering
424 Turnbull Canyon Rd.
City Of Industry
CA  91745
DC Sports
768 S. Turnbull Canyon Rd
City of Industry
CA  91746
817 Lawson Street
City Of Industry
CA  91748
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