In an era when front-wheel drive was king, the 1991-1998 Nissan 240SX was one of the last rear-wheel drive sport coupes that combined affordability, reliability and practicality. It was and still is the cheapest offering with a solid roof, reasonable back seats, a reliable engine and an independent multi-link rear suspension.
During the 240's production, Nissan shipped them here by the boatloads-at least the 1991-1994 S13 model. That means you can find an S13 salvage chassis for less than $1,000, while a newer '95-'98 chassis, the S14, will start at around $7,000 (everyone wants one for drifting).
The big advantage of the 240SX is the number of O.E. and aftermarket parts made for the chassis. Nissan's cookie-cutter method of vehicle design means that the 240SX shares interchangeable components among different generation chassis (from the S13 to JDM S15s). Parts from other 240SXs or more expensive rear-drive Nissan/Infiniti platforms like the 300ZX and Skyline offer cheap, reliable upgrades that can be had for a fraction of the cost of new aftermarket parts.
The biggest gripe with the 240SX, however, is the U.S.-market S13 and S14 engine. The underpowered DOHC 2.4-liter iron block KA24DE-forever known as a truck motor by American enthusiasts-is often discarded in favor of the Japanese market SR20DET turbo 2.0-liter engine.
There's an easier and less expensive alternative: strap a turbo onto the stock KA24. Few realize the power potential available from this setup, not to mention the boost in chassis twisting torque the KA24 is best known for. And because everyone is throwing away their KA24s, there are limitless motors to pick from for pocket change (The KA24DE is also used in some Nissan trucks and Altimas).
Turbocharging a KA24 can be as simple as buying a bolt-on kit from reliable sources like XS Engineering, GReddy, FMAX or Turbonetics. If you have the time and resources though, a boost-it-yourself solution can be easily done for less than $2000.
The KA24DE is a direct descendant of the L16 engine originally found in Datsun 510s, which means that the old cast-iron bottom end of the KA24 is able to withstand tremendous punishment. The same applies for the transmission and R200 rear end.
A stock KA24, which has a 9.5:1 compression ratio, can handle up to 12 psi of boost on pump gas if properly managed. On a larger turbo, this means about 300-wheel hp. Even with just the stock fuel system and a rising rate fuel pressure regulator, the KA24 will run happily on 7 psi of boost, which will get you roughly 225-wheel hp. That's almost 100 more than stock (127-wheel hp) and more than any stock SR swap will get you. The 2.4-liter displacement also means more exhaust gas and less lag. The combination of low-end torque and mid-range boost makes for an incredibly fun street car. Throwing on a turbo also stretches the powerband well past 5000 rpm, where the stock KA24 runs out of breath.
The KA24DE's biggest problem is high piston speeds; it can't spin reliably past 7000 rpm on account of the rod-to-stroke ratio, limitations of the timing chain and half-counterweighted crank. Even Nissan's fully built KA24 race motors redline at just 8500 rpm.
By Henry Z. Dekuyper
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