During the first generation, three body styles were available: fastback, coupe, and convertible. The coupe is closely related to the Japanese-market Silvia except for having retractable headlamps. The fastback is closely related to the Japanese-market 180SX. The convertible, introduced in 1992, was exclusive to North America and was the only body style available in 1994. The convertible was partially assembled in Japan, with final assembly taking place in the California facilities of American Specialty Cars (ASC). All S13 240SXs were largely similar with differences between trim lines (XE, SE, LE, etc.) being mainly cosmetic (1989-1990 240sx's are considered the "pignose"). The lone exception, the 91-93 SE fastbacks, had an exclusive optional sport package containing a stiffer suspension, a limited-slip differential, and SUPER-HICAS 4-wheel steering.
The S13 was known for its sharp steering/handling (thanks to a front strut, rear multilink suspension and light weight (2600lb) but was regarded in the automotive press as being underpowered. The Nissan KA24E engine, while durable, was a heavy, iron-block unit that produced meager power for its size 140–155 hp (104–115 kW), but with slight improvement in the form of a 16-valve twin-cam KA24DE in 1991. This engine is the main distinction between North America's 240SX and world-market Silvia/180SX. As the cars have aged, Japanese SR20DET engine swaps have become an increasingly popular 240SX modification. At the same time, a large community has developed of owners turbocharging the 2.4 L KA engine, with great success.
http://en.wikipedia.org/wiki/Nissan_240SX