Picking the Chassis

Picking the Chassis

The S13 240SX came as a fastback, coupe and convertible. The convertible is heavy, flexible and was only available with an automatic. If you're building a sports car, don't start here. Of the remaining body styles, the coupe is slightly lighter (about 50 lbs., depending on options) and stiffer, thanks to the added structure behind the rear seats.

The 240SX was available with ABS, a viscous limited-slip differential, and Super HICAS four-wheel steering. ABS from this era is relatively primitive, so we tend to avoid it. The HICAS system is probably another one to avoid. The rear-wheel steering is sometimes in phase and sometimes out of phase with the front wheels, and many people find it unpredictable and unsettling. There are several kits available to eliminate the system on cars that have it.

We've only experienced the system on Skylines, where it works quite well, so we can't comment on its effectiveness in the S13. A limited-slip differential is absolutely critical for what is about to be a very powerful car, but only cars with Super HICAS had the limited slip. If you can't locate a car with one, you can find one in a junkyard from a 240SX (all Canadian 240SXs had them) or a 300ZX, or there are aftermarket limited slips available. If you get a 240SX limited slip, be sure to get the driveshaft as well; it's about an inch shorter.1989 and 1990 models had a single-cam, 12-valve KA24E, while '91 and later cars used the twin-cam KA24DE. Since you're removing the engine anyway, this matters little, but the swap is a little easier starting with a twin-cam car. The power-steering lines from the earlier engine don't line up with the SR20's power-steering pump, and the tach signal from the SR20 won't drive the single-cam tach.

We found a relatively straight 1989 240SX coupe with 270,000 miles and a hole in the engine block for $800. It has no ABS, no HICAS, and, unfortunately, no LSD. It also has no sunroof, which is critical for tall drivers. Still weighed down with air conditioning, power windows and a fender full of Bondo, it tipped the scales at 2,710 lbs. before the conversion.