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Whats my dynamic compression?

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Old Feb 24, 2026 | 06:24 PM
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MixdPlate's Avatar
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Post Whats my dynamic compression?

First posts so dont go too hard. This is also my first LS build..

Trying to find my dynamic compression ratio. I tried using the online calculators but im getting some high numbers. I live in Hawaii so its mostly sea level driving, 92 octane only, no e85, I do not want to use octane boosters.
The online calculators are giving me 10.7:1 STATIC / 9.8:1 DYNAMIC

LS1
PRC 225 HEADS 62CC Chambers
3.903 bore
-3.2cc pistons
3.622" Stroke
.045 head gasket
4.035 gasket bore
6.125 rods
Deck clearance: .006 out of the hole
I currently have a tsp 228R 112 lsa cam but do not have the cam card so I assumed the ABDC @ .05 to be 42*. Is that right? I will replace the cam if needed but I'd like to use it if I can. Any cam recommendations welcomed. Car will be mostly a street car with some skid racin if a track ever gets built here.

Last edited by MixdPlate; Feb 24, 2026 at 06:40 PM.
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Old Feb 25, 2026 | 07:46 AM
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You need the ivc at .006 to get the correct dcr. I would ask tsp.
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Old Feb 25, 2026 | 07:49 AM
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10.7 static should be able to use any cam without concern, but yes you need the actual closing event to calculate dynamic.
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Old Feb 25, 2026 | 12:01 PM
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Originally Posted by SLP IROC-Z
You need the ivc at .006 to get the correct dcr. I would ask tsp.
Mahalo for the clarification! I see why the dcr is high in the calculator.
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Old Feb 25, 2026 | 01:07 PM
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0.006 is the spec you need for most if not all DCR calculators.
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