ok, this is what i have read in to. (obviously DOHC has two cams and SOHC has one) The other differece is that in a SOHC motor has only v-tec intake lobe and there is not enough room for the v-tec exhaust lobe. The DOHC motor has a intake cam and a exhaust cam allowing for a v-tec lobe on both cams. ( plz correct me if im wrong)