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SCR effect on DCR

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Old Oct 12, 2013 | 01:45 PM
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Default SCR effect on DCR

Does the static compression ratio make a difference in the dynamic compression ratio or are they completely separate from eachother?

I ask this because I'm using a DCR calculator from I believe a guy called pianoprodigy. Using the OEM settings for my engine and the camshaft I'm running and I get 8.65 DCR...cool.

But then when I go change the headgasket thickness to say 0.040 to increase the SCR, the DCR also goes up even tho the cam specs remained exactly the same.
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Old Oct 12, 2013 | 01:54 PM
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yes SCR effects DCR. From what I have read 8.5 DCR is a good number to shoot for if running pump gas.
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Old Oct 12, 2013 | 02:04 PM
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yes SCR effects DCR
Dang then I need to re-think my camshaft selection completely. I've been using the DCR calculator independently of the SCR info and came up with a cam that gave me around 8.6 DCR with 10.9 SCR. But with 11.5 SCR the DCR jumped to 9.1

Does that make sense that it would jump that much?
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Old Oct 12, 2013 | 02:54 PM
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That doesn't sound right at all.
It should only be about 1/3 of a point increase in SCR, and about 1/4 point increase in DCR with that change to a .04" gasket; at least for a LS1 motor.
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Old Oct 12, 2013 | 02:58 PM
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It's an LS2, going from 10.9 to 11.5 with milled heads and 0.040 gaskets.

A 226/234 cam with IVC 40* comes up with 8.6 DCR on stock compression.

The same cam comes up with 9.1 DCR on 11.5 compression.

Maybe I'm just using the wrong calculator.
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Old Oct 12, 2013 | 03:15 PM
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If you retard the cam about 4* for your current ICL it'll drop the DCR back down to about 8.65. The possible down side is that it'll shift the power band up about 300-400 rpm. Now if you want to shift the powerband up higher then that's a plus.
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Old Oct 12, 2013 | 04:54 PM
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Yeah that's probably what I'll end up doing, just wanted to make sure that it sounded correct before I go and change the cam specs.
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