I own an 86.......I have always been told 235hp. and 87 245hp. I have never found any info to show what differance was. That is until I watched u tube video. Title of video buick grand national facts. It is 42:37 in length and is presented by Ron Yuille SAME HP FOR 86 & 87. go to 17:15. - 19:00. have a nice day