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psi to compression ratio

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Old May 26, 2006 | 05:09 PM
  #1  
z28z34man's Avatar
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From: IA
Car: 1984 z28 camaro / 2019 accord sport
Engine: 350
Transmission: 700r4
Axle/Gears: 3.42
psi to compression ratio

i have 160 cold psi what would that be in compression ratio

also several of my plugs were oily when i changed them that is why i did the compression test. 160 psi would be a good signal that the rings are good and it is my valve seals that are bad.
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Old May 26, 2006 | 05:10 PM
  #2  
84z28350's Avatar
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From: Yellowknife, NWT, Canada
Car: 84 Z28
Engine: 357
Transmission: TH-350C
Axle/Gears: 3.43
It could be anything...


CR is calculated with piston dome/dish size, bore size, headgasket thickness and bore and last but not least combustion chamber size.
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Old May 26, 2006 | 05:29 PM
  #3  
rx7speed's Avatar
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From: Caldwell,ID
Car: 2005 BMW 545i
Engine: 4.4L N62B44
Transmission: 6spd auto
Axle/Gears: Rotating
cranking compression can change depending on a lot of things
take two motors both with 10:1 compression one with smaller heads, smaller cam and so forth. might have a cranking psi of around 200plus
take the same 10:1 compression motor with a huge cam huge heads all full race setup. might pull cranking compression of 150-160psi
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Old May 26, 2006 | 05:46 PM
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Sonix's Avatar
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From: Calgary, AB, Canada
Car: 1982 Trans-Am
Engine: 355 w/ ported 416s
Transmission: T10, hurst shifter
Axle/Gears: 10 bolt, true-trac, 3.73
it's the variation between cylinders that you care about. all within 10psi of 160psi ? you're good.

yep, swap out them valve seals first, it's easiest.
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