why is the nissan 240sx so good at drifting compared to other rear
wheel drive cars?

http://motortrend.com/features/consumer/112_0407_race_drift/index2.html

it doesn't answer your question, but it is an interesting article.

It has to do with the front to rear weight ratio and how tight the
front suspension is.  Think gocart.  You can make any car drift try
putting weight (sand bags) in the back or front and tighting up the
suspension.

When I was a LOT younger we would do this all the time.  If you want
to drift, try dirt, it's easier and cheaper(tires?).

The 240 is no better than any other front-engined/rear-drive car. It's
simply answered that as drifting was popularized, the 240 (along with
the RX-7 and early the Corolla AE86) were the cheapest FR cars that
could be slightly tweaked to drift well. Any car can drift. A FR car
will drift easier. And a cheap car is better if you're going to toss
it around like it's your job.

Well, drifting cars are tuned for drifting.....nissan 240sx is
light...weight is very important in drifting ... cars need to be very
light..and 240sx is very light and has just enough horsepower to bring
the tires off traction to start the drift, the weight ratio is good
too because a drifting car is aimed at around 50/50 (front/rear) the
back suspension should be loose front suspension should be
stiff.......the back suspension should be higher than the front
suspension so that the weight is easily shifted to the front as you
break....you also need special brakes too...you would want your front
brakes to enact before your rear so you your weight shifting would be
better suited for drifting...you do this by taking out the meter
valve.......basically any car which is light and a rear wheel drive
layout and has enough horse power can drift easier than most
car,,,especially with drifting tuneups a car would be great for
drifting........some cars aren't as light as 240sx but they still have
rear wheel drive...and light cars are better in drifting so the 240sx
would be better than that car;).....there are also factors that effect
drifting like downforce, engine, tires but i won't go into those
details heheh...