Editing Dynamic compression ratio

{{youcanedit}} Just for grins, I calculated different static compression ratios with a 3.48" stroke and different camshaft intake closing points @ 0.050" tappet lift on Keith Black's dynamic compression ratio calculator. The calculator went did work poperly on 8.00-1, so we'll start at 8.25 SCR. I kept the DCR at just over 8.0, a figure that is well accepted for operation of the motor on pump gas with a little cushion... *Static CR....Intake closing point @ 0.050"....Dynamic CR. *8.25........10* ABDC......8.010........................................................................................................ *8.50........20............8.012........................................................................................................ *8.75........27............8.022........................................................................................................ *9.00........33............8.018........................................................................................................ *9.25........37............8.061........................................................................................................ *9.50........42............8.029........................................................................................................ *9.75........46............8.016........................................................................................................ *10.00.......49............8.038........................................................................................................ *10.25.......52............8.043........................................................................................................ *10.50.......55............8.029........................................................................................................ *10.75.......57............8.069........................................................................................................ *11.00.......60............8.022........................................................................................................ *11.25.......62............8.038........................................................................................................ *11.50.......64............8.042........................................................................................................ *11.75.......66............8.035........................................................................................................ *12.00.......68............8.017........................................................................................................ Now, it's unclear where these Keith Black DCR calculator dynamic cr readings are taken, at cranking rpm's or at max efficiency rpm's. But I can tell you this from playing with the DynoSim, max cylinder pressures are made at or near the torque peak. So, the fact that a motor is not detonating at low rpm's does not mean that it will not detonate at or close to the torque peak. These numbers may not mean anything at all, but they do illustrate that you cannot just pick a cam out of thin air like a lot of fellows do and expect it to work best for your particular combination. [[Category:Engine]]

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