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2003 Cobra - 10:1 compression - Cold compression check

Discussion in 'Engine/Tuning' started by G3T_TERMINATED, Mar 9, 2020.

  1. G3T_TERMINATED

    G3T_TERMINATED New Member

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    Mar 16, 2013
    Location:
    Nebraska
    I've got Manley pistons with a 10:1 compression ratio. I tested my cold compression today, the lowest cylinder was 148 psi and the highest was 161 psi. These are within the 10% threshold. Low cylinders were 5 & 7 @ 148 psi. I need to do a warm check to be sure. But what is an average psi for 10:1 CR? I'm getting the car ready for more boost and want to make sure she's healthy.

    Cylinder : PSI
    4: 152. 8: 152
    3: 157. 7: 148
    2: 160. 6: 161
    1: 152. 5: 148

    Any input is appreciated.
     
  2. olympic

    olympic Well-Known Member Premium Member Established Member

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    Dec 28, 2014
    Location:
    SK, Canada
    Seems about right. Mine was a in the 140's with 9.1:1.
     
  3. CompOrng04

    CompOrng04 Still a Rookie Established Member

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    Oct 13, 2012
    Location:
    Hinesville, GA
    You guys cracking the throttle body? My stock 04 cobra engine (8.5:1) and others I've tested are typically in the mid 150's to low 160's. Just curious.
     
  4. Quick Strike

    Quick Strike Well-Known Member Established Member

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    Sep 27, 2003
    Location:
    PA
    Aftermarket cams will generally lower the cranking compression if you have them.
     

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