PSI Compression Numbers

[Mazda7]

Hi, I'm posting on behalf of a friend. He and I would appreciate your help in this matter. He just did a compression test on his 94' Mustang GT 5.0 and it ran 135 PSI in all 8 cylinders. He and I are wondering what would be a good compression? Alternatively what would be poor compression?

 

[wytstang]

That sound about right you have to remember a ten year old motor is not in it best form but those numbers are about right.

 

[Slow5.0]

Mine was 180psi at all 8 cilynders with 100K, now with TFS heads is 175psi

 

[smokediver27]

Dont sound too bad mazda, my car was poorly cared for before i got it and mine are all 145-150

 

[Mazda7]

I see, so it's kinda low but still ok. Thanks for your replies.