Dynamic CR Ratio
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Teching In
Joined: Jul 2025
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Dynamic CR Ratio I have owned a few LS based engines in trucks but this is my first time building one. I am looking to build a 408 stroker and my target static CR is 10.3 to 1. I am going to use a TSP Stage 3 truck cam which I used a dynamic CR calculator and it put it at 8.89 to 1. I read that 8.5 to 1 is the limit on pump gas and Im not understanding how my dynamic CR is so high, plenty of vehicles come from factory with over a 10 to 1 CR and much milder cams then what I am going to run and obviously use pump gas just fine. Is my compression okay for pump gas or do I need to lower it?
I have owned a few LS based engines in trucks but this is my first time building one. I am looking to build a 408 stroker and my target static CR is 10.3 to 1. I am going to use a TSP Stage 3 truck cam which I used a dynamic CR calculator and it put it at 8.89 to 1. I read that 8.5 to 1 is the limit on pump gas and Im not understanding how my dynamic CR is so high, plenty of vehicles come from factory with over a 10 to 1 CR and much milder cams then what I am going to run and obviously use pump gas just fine. Is my compression okay for pump gas or do I need to lower it?
Is your engine an iron block or aluminum, aluminum heads, or iron? Aluminum heads will let you get away with higher compression. IMHO, you should run as much compression as you can, especially in a truck. The key wording here is "as much as you can."
