If it's a 2.0S then it's the B20A3 engine. Single cam, Dual Carburated. makes about 105HP. if you're looking for that generation prelude, I'd hold out for a fuel injected one.

trunk lids and emblems can be swapped easily though, so to be really sure, either look under the hood or at the VIN number (JHMBA411 = B20A3, 2 = B20A5, 3 = B21A1 (90-91 only), 4 = 4WS w/B20A5 (88-89) or B21A1 (90-91), 5 = ALB w/B21A1 (90-91 only)