Look at this way. On my small blocks I am up 90 cubic inches, but the duration on the cam for street use will stay about the same. I have gone 3.31" to 4.125" stroke and the duration at .050 maybe go up from 228 to 232. The factor that will be the same is the top end(heads,intake,carb) If you go really big ported heads to make the motor work, you loose port velocity and the motor is a dog under 3000 rpm. This all comes back to how every component works together.
