Power Pages: 1996 Nissan 240SX SE

THE FACTS
Engine tested: KA24DE
Application: 1996 Nissan 240SX
Common Swaps: SR20DET & CA18DET

Nissan's 240SX/Silvia platform has long been a favorite of performance-minded drivers. A front-engine, rwd configuration combined with well-engineered driving dynamics makes the 240 a winner. Unfortunately, the USA's draconian anti-pollution regulations meant that American buyers had to settle for a re-hashed truck engine (KA24DE) in place of the Silvia's Turbocharged 2.0-liter SR20DET. Other than that, the American market 240 is a first-rate package and a great basis for further modification. With an independent suspension at all four corners and (in this case) anti-lock brakes and a limited-slip differential, the potential of the chassis is first rate. All we need to do is inject a little life into our powerplant.

The Engine
The KA24DE has been a workhorse in the Nissan product line since its introduction in 1991. The 2.4-liter, four-cylinder, double-overhead-cam design is renowned for its reliability, as befits an engine that would find a home in Nissan's pickups as well as the 240SX.

A look at the specs reveals the thinking behind the KA design. An 89mm bore combined with a 96mm stroke is a recipe for an engine that is designed to produce torque. The long-runner intake manifold is a further indication of what Nissan's engineers had in mind.

In stock form, the engine produces a little over 150 hp at 5500 rpm and 160 lb-ft of torque at 4200 rpm. Drive a 240SX and it's obvious the strategy works--the KA24DE pulls without hesitation from low rpm and has a strong midrange. However, once you venture past 5500 rpm the power starts to drop away, and the smart thing to do is short-shift and let the torque continue to do the work. It's not the most exciting way to drive, and definitely not in keeping with the 240SX's sporty character and awesome chassis.

Performance Components
After consulting our friends at CTC Motorsports in Dallas we decided on a three-way strategy in our first efforts at releasing some much-needed horsepower. Like many enthusiasts, we targeted the easiest modifications in an attempt at instant gratification. CTC's head honcho Kyle Thurber recommended we free up the breathing capabilities of our engine with an Injen cold-air intake system and a 5Zigen cat-back exhaust. Also on Kyle's list of recommendations was a set of underdrive pulleys from the team at Unorthodox Racing.

Unorthodox Racing's Ultra SS pulley set consists of four replacement pulleys: crank, A/C compressor, power steering and alternator. Power gains from this set are primarily from the reduction in rotating mass that machining the pulleys from billet aluminum allows. The pulleys increase net power further by under-driving the accessories, helping to reduce the parasitic power losses by a considerable degree. Installation was a breeze: Wayne Potts, CTC's head mechanic, had our set installed in about an hour. Incidentally, the drive-belts have to be replaced because of the changes in pulley size, but thanks to a very useful belt guide on the Unorthodox Racing Website (www.unorthodoxracing.com) this was hassle free. Once equipped with the correct part numbers we went to our local NAPA parts store and picked up a set for about $30. Next on our list was the Injen Technologies cold-air intake. We also decided to install Injen's optional cold-air extension, which relocates the high-flow cone-filter element to the inner fender and ensures the engine gets a healthy dose of cold, fresh air rather than the hot, turbulent air found under the hood. The Injen system is manufactured with mandrel-bent aluminum tubing that, in our case, was anodized red. TIG welds are all artfully carried out and the system also includes a polished aluminum MAF adaptor that adds to the "high- tech" looks of the system. Installation was a piece of cake. After removing the stock system we relocated the MAF sensor onto the Injen adapter and installed the intake temperature sensor. The inner fender splashguard was unscrewed and the air filter installed in its new home, then the tubing was installed with the silicone connectors. After hooking up a breather and vacuum line we were finished.

Choosing a cat-back exhaust system for the 240 was a no-brainer. We didn't want to install a 4-in.-bore monster pipe that would result in a severely depleted mid-range on our naturally aspirated KA24DE powerplant, so after consulting the experts at CTC Motorsports we decided to go for a 5zigen Fireball system. The 5zigen system is designed specifically for naturally aspirated applications, unlike most of the systems that are imported from Japan and designed to work with the Turbocharged SR20DET engine. Minimal exhaust restriction is a good thing on any turbocharged application, but our requirements demanded a system that would provide enough backpressure for efficient engine operation while at the same time minimizing restrictions and adding to the power output.

The 5zigen stainless-steel muffler is a high-flow design mated to a mandrel-bent 60.5mm system that includes a resonator box to keep noise at a civilized level. The exhaust piping is painted with a corrosion resistant coating and the system came complete with the gaskets required for installation. Overall, the quality of the 5zigen system is evident in the build and design. Everything fits the way it should and all of the components are made to the highest standards. Once we had the car up on a lift, installation was once again an easy process. The stock (and rather corroded) system was removed and the 5zigen bolted up in about 30 minutes. I wish all installations were this simple. Dyno Testing
After strapping our 240 on the Dynojet at Intercrew Auto Salon in Richardson, Texas, our baseline dyno runs revealed that despite showing more than 120,000 miles on the odometer our KA24DE is in remarkably good shape. Power maxed out at 129.7 hp at the wheels and torque clocked in at 144.9 lb-ft. Peak horsepower was seen at 5700 rpm and our torque peak was at around 4300 rpm.

Our next session on the Intercrew Dyno occurred after we installed the Unorthodox Racing Ultra SS pulley set. The tests revealed we had gained some much-needed horsepower throughout the range. From 3000 to 4000 we picked up about 5 horses. From 4000 rpm and up the increase was steadily better with a whopping 12-hp increase at around 6300 rpm. Our peak numbers increased from 129.7 hp to 138.1 hp. Torque peak was improved to the tune of 6 lb-ft at 4200rpm with a final number of 150.9 lb-ft. Seat-of-the-pants testing revealed our 240SX was definitely a lot more willing. Throttle response was much bette,r and despite under-driving the accessories, our car's charging system, power steering and air conditioning were unaffected in any way.

Our next tests took place after we installed the Injen Technologies cold-air intake. After spinning the rollers, the graphs revealed a huge increase of 13 lb-ft of torque at 3500 rpm and a peak increase of 3.4 lb-ft at 4300 rpm. Maximum horsepower was increased by 5.1 and the biggest gain, about 10 hp at the wheels, was realized at 3600 rpm. Overall, the Injen intake made a significant difference in the way our 240SX drives. The bulge in the powerband at 3500 rpm is extremely evident when accelerating from a standstill. The kick-in-the-pants feeling carries on all the way to the redline and is accompanied by an awesome intake roar--a side benefit of the free-flowing Injen system. Under the hood the red anodized piping and matching hoses jazz up the looks and advertise the intake's presence.

Our final tests on the Intercrew dynojet came after we installed the 5Zigen Fireball cat-back system. The 240 spun up the rollers and the charts revealed positive results yet again. Horsepower and torque were both increased from 3000 rpm to redline. Peak power was increased from 143.2 to 146.8. Peak torque numbers increased from 154.3 to 158.0. The biggest difference was seen at around 4000 rpm where the 5Zigen Fireball generated about 10 hp more and went a long way to filling the dip in the midrange. From 4500 to 5500 rpm our power was increased by a very handy 8hp on average. On the street the 5Zigen exhaust sounds just right. Its deep, sporty tone is not annoyingly loud on the freeway, yet still sounds great when you're doing Michael Schumacher-style racing downshifts. The stainless-steel muffler is aggressively styled but is not going to garner any "coffee can" comments from domestic pilots.

Conclusion
These mods have totally transformed our S14 240SX--with an overall increase of 20+ hp at 6300 rpm and 20 lb-ft of torque at 3500 rpm, the engine feels like it belongs in the car. Our engine now revs like a champ and is a whole lot more fun to drive.