Editing Dynamic compression ratio

{{youcanedit}}
==Online calculators==
*[http://www.wheelspin.net/calc/calc2.html SCR calculator]
*[http://www.wallaceracing.com/dynamic-cr.php Wallace Racing DCR calculator]
*[http://www.empirenet.com/pkelley2/DynamicCR.html Kelly DCR calculator]
*[http://www.kb-silvolite.com/calc.php?action=comp2 KB/Silvolite DCR calculator]
*[http://www.rbracing-rsr.com/comprAdvHD.htm RSR DCR calculator]

{{Note1}}If the intake closing (IC) point isn't known, it can be calculated:
# Divide the intake duration by 2
# Add the results to the lobe separation angle (LSA)
# Subtract any ground-in advance
# Subtract 180 
This result does not need to have any amount added, like the KB calculator calls for.

==DCR and pump gasoline==
It's worth mentioning that 8.5:1 DCR is considered to be the maximum for iron heads and 92 octane fuel (MON + RON divided by 2).

==SCR vs. DCR vs. duration==
The following are different static compression ratios (SCR) 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, starting at 8.25:1 SCR. The dynamic compression ratio (DCR) has been kept at just over 8.0:1, a figure that is acceptable for use with today's 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........................................................................................................

==Disclaimer==
Now, it's unclear where these Keith Black DCR calculator dynamic compression ratio readings are taken; at cranking rpm or at max efficiency rpm. According to the DynoSim software, maximum cylinder pressure is made at or near the torque peak. So, the fact that a motor is not detonating at low rpm 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]]
[[Category:Cylinder head]]