Hi,
Your car as you have probably figured out now is a B12. "B12" refers to the chasis that was produced from 1987-1990 in the USA, 1987-1993 in Canada, and is still in production in Mexico.
The B12's came in a whole pile of different trim levels, XE, GXE, DLX, and some others. The different trim levels basically were interior stuff, some had a decent stereo, some had A/C etc, some had nice taillights, some didn't.
The B12's came with 2 engines. the 1987-1988's had the E16 engine. This engine cranked out 70hp.
The 1989-1990's had the GA16i. Predecessor to the GA16DE, the GA16i produced 92 Hp, and 96lb-ft of torque.
Both engines are 4 cylinder inline engines with a 1.6 liter displacement.
You may hear some people talking about SR20's.
SR20's are probably Nissans most famous engine. It came in a ton of cars starting with the 1991(?) Sentra SE-R. and ending with the 2001 Sentra SE.
It is a 2.0L inline 4 cylinder Engine that produced 144 HP in stock form. Later versions had turbos and stuff and prodcued much higher HP numbers. With just a few mods SR20's can produce over 200 HP.
Most people who want to make their B12's go really fast ditch their E16 or GA16i for SR20s.
Swapping an SR20 in place of an E16 or a GA16i is simple because they use the same motor mounts.
Basically, it all depends on what you want. If you cant afford a Turbo or Nos, your E16 or GA16i will probably never produce more than 150 Hp.
If you want to be all out performance just like "FAST AND THE FURIOUS" do an SR20 swap... if you can afford about $2,000 for a used SR20.
If you need any more info on this stuff, check out
Sentra.net , they have tons and tons of info that you may find useful.
Hope I helped!!
-Nick