si engine is a d16a6. It says what the motor is on it. I think the rear suspension on the si has a rear sway bar and others don't. Si's and like the 91 dx's have body colored bumpers, not black. The interior is a lot sportier, kinda like racing buckets. I think si crx's have rear disc brakes, but i'm not certain what years and stuff, i got a 91 hatch so i only know some about them. There's a little help 'til someone adds on.