Compression Reading Difference Between High Elevation & Sea Level

[TheShopForestry]

Hello everyone, I'm struggling with the T540XP I & II compression readings gone through three new oem cylinders and gotten the same low comp numbers each tim even after break in procedure. So my question for this thread is if there is a going to be a 30 psi difference in top end compression going from sea level to 3600 feet. For example if comp psi reads 135 at sea level is it possible for the exact same gauge to only read 105 psi up in the mountains at 3600 feet. If there is an equation that someone might have to figure out whether my gauge is faulty or its accurate i just have to adjust my reading for the higher elevation I am working at.

 

[bwalker]

Did you try a different gauge? Compression gauges are often not very accurate.
Also with a new piston and cylinder you will have compression. Forget the number and just use the gauge to track change.

 

[bwalker]

And yes you will lose compression as altitude goes up. I highly doubt your losing that much compression at 3600 feet.

 

[nedsim]

Hello everyone, I'm struggling with the T540XP I & II compression readings gone through three new oem cylinders and gotten the same low comp numbers each tim even after break in procedure. So my question for this thread is if there is a going to be a 30 psi difference in top end compression going from sea level to 3600 feet. For example if comp psi reads 135 at sea level is it possible for the exact same gauge to only read 105 psi up in the mountains at 3600 feet. If there is an equation that someone might have to figure out whether my gauge is faulty or its accurate i just have to adjust my reading for the higher elevation I am working at.

Yes, there will be a measurable difference between sea level and 3600 feet. But assuming constant atmospheric conditions I don't think the difference would be as large as what you're describing. A back of the envelope calculation gets me 115-120 psi at 3600 feet. Haven't tried to figure out how much difference a high pressure vs. low pressure weather system would make.