bob, i used cochises dcr calculator only to find out the dcr is 7.127. results are rd=1.762, rr=.641, pr1=6.535, pr2=5.894, dst=2.749. calculating compression ratio with dst instead of stroke gives the afformentioned dcr results. those thinking you should use .050 measurements instead of advertised ones should read your link to cochise`s dcr calculation. compare these results with yours to find out where you made a mistake. thanks, serge.