i use wallace racing`s calculator. i have my own formula to calculate dcr and both give me 7.12 or 7.13 dcr. input numbers to plug into the wallace racing calculator are bore=4.35, stroke=3.75, rod length=6.768, static cr=9.35, altitude=0, boost=0, 8cylinders and intake closing point=70*. it should give you the same results as mine. you can use their calculators they are accurate and very powerful.

Pretty sure wallace uses .050 numbers it's the same as this

http://www.rbracing-rsr.com/comprAdvHD.htm

Static compression ratio of 9.35:1.
Effective stroke is 3.39 inches.
Your dynamic compression ratio is 8.57:1 .
Your dynamic cranking pressure is 173.77 PSI.
Your dynamic boost compression ratio, reflecting static c.r., cam timing, altitude, and boost of 0 PSI is 8.57 :1.
V/P (Volume to Pressure Index) is 210

I have a detailed dyno program and it gives the same cranking compression!

Who said @.050 is @.050!

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.

Dynamic compression ratio is just a re-calculation of compression ratio using the piston position at the point the intake valve closes, and technically it would be the point where reversion out of the cylinder stops. Because DCR is used to estimate cranking cylinder pressure, and cranking speed is very slow, the 0.006" "Advertised" duration number is used to estimate the intake valve closing point.
If you had zero lash and 1.5:1 rocker arms (and no deflection of parts) the valve would only be open 0.009" with 0.006" lobe lift. This 0.009" is what the calculation is estimating to be the point where the valve "looks" closed and has captured the newly calculated cylinder volume of air/fuel at the atmospheric pressure. With a solid cam the valve lash would have to be factored in. The equation then takes the new Dynamic compression ratio DCR raised to the power 1.2 (the 1.2 is an estimate of the polytropic heat ratio of compressing the air/fuel mixture), and multiplies it by the atmospheric pressure to get absolute chamber pressure at TDC (DCR^1.2 * 14.7.) Gauge pressure is just the absolute pressure - the reference atmosphere pressure.
In theory (with no heat lost to the engine) the gas temperature would also be increased by the DCR. That is why having cool incomming air/fuel helps lower the chance of detonation, because that temp is multiplied by the DCR. But also the heat is dissipated into the surrounding engine parts, so if the engine temp is lowered it also helps reduce detonation. On the flip side, on combustion a cooler engine also absorbs more heat energy so it is thermally less efficient.
The 0.050" duration numbers are not used for DCR calculation because the valve would be too far open (0.075") to be the capture point (at cranking speed.)