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  1. JoseK5

    JoseK5 Registered Member

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    Hi there,

    What compression ratio should one shoot for when building a 383, destined to receive 94+ octane gas.
    Thanks
     
  2. 4X4HIGH

    4X4HIGH 1 ton status Premium Member GMOTM Winner

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    If this engine is to be used in a truck or blazer i would keep the compression down around 9.5:1
     
  3. fortcollinsram

    fortcollinsram 1/2 ton status

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    If you are gonna honestly pay to put 94+ Octane in, I'd shoot for 10.5 or 11:1...If you wann run the cheap stuff, keep it below 9.5
     
  4. 4X4HIGH

    4X4HIGH 1 ton status Premium Member GMOTM Winner

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    The problem you will encounter by using a higher compression ratio is that you also need to run a bigger cam, manifold, carb, or TBI and this all adds to making HP/torque at higher RPM's. For a truck or blazer you want the torque down low in the RPM range not up high like a race car. You will not have to worry about the engine pinging or anything like that but like i said, you raise the effective HP/torque level to a higher RPM that a truck or blazer will never see unless it is a balls out mud bogger.
     
  5. CaptCrunch

    CaptCrunch 1/2 ton status

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    Depends on a small ton of things like deck height, head selection... alum or cast heads, FI or carb, quench, cam, etc. etc. generally for a car motor with regular cast iron heads 10 to 10.5 to 1... you can do more depending on what you do. I have seen guys run 11.8 to one on 92 with very little retarding the timing. I personally ran a 355 small block with world torquers with approx 11 to 1 on 89 with minor retarding... but lived all day long on the street and if I wanted a touch more power and rpm I would 92.

    what is your planned setup?
     

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