2.3L & 2.5L I4 Tech General discussion of 2.3L and 2.5L I4 Ford Ranger engines.

Compression

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Old 06-13-2009
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Compression

What is the cylinder pressure suppose to be at? Also what is the service limit?

I need this in psi, not the compression ratio.

IE. 190psi a cylinder.
 
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Old 06-13-2009
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It would really help if we knew what engine you have. Not all have the same compression you know.
 
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Old 06-13-2009
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Oh yeah my bad.

2.3L
 
  #4  
Old 06-13-2009
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As a general rule of thumb compression pressure reading should be no lower than 100 psi and should not very more than 25 psi between your highest reading cylinder and your lowest reading cylinder. It’s more important that all cylinders read about the same plus or minus 25 psi rather than how high the readings are, given that none read below 100 psi. However, you will need to do both a dry and a wet test to help determine which components may be at fault if any. You can also do a cylinder leak down test or a variant of a compression test can be done at a shop using a diagnostic scope that's capable of reading the battery amperage required to crank the engine over per cylinder.
 
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Which 2.3L?
 
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Old 06-13-2009
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Originally Posted by Johnbaum13 View Post
Which 2.3L?
His profile says he has a 94 ie old school 2.3.
 
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Old 07-24-2009
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yay college physics

Referenced from therangerstation tech library 1994 2.3L had a compression ratio of 9.4:1

From basic physics Boyle's law states that pressure1 * volume1 = pressure2 volume2 aka P1*V1=P2*V2
If we assume the incoming air is at standard atmospheric pressure at sea level or 14.696psi we can estimate the compression pressure

14.696*9.4 = x*1 where x is our compressed pressure
x= 138.1424psi assuming incoming air is at 1atm or 14.696psi

You may need to adjust for elevation if you live far enough away from sea level to make a noticeable pressure difference.

For example in Denver Colorado the pressure is approximately 12.1 PSI
so 12.1*9.8=x*1
or 118.58psi when compressed
 
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