It seems like, with a 9.2:1 compression ratio, it'd be 9.2x atmospheric pressure. 9.2 * 14.7 psi = 135. That seems low though. Someone on another thread said 175 psi, but wouldn't that require a much higher compression ratio? How would you get more than 9.2x of whatever you have to work with?
I did a compression test today on my 1995 4.0 with 233k miles. Engine had been driven about 3 hours before, so it was getting cool. My numbers were...
123
115
123
120
127
123
Some people were saying these are bare minimum- ready for a rebuild. However, I'm at nearly 6000', and it was a warm day. Altitude alone has a .836 correction factor, which would give me...
147
138
147
144
152
147
So, those alone bring me up to above my 137 theoretical max. Two questions:
1) How do you get cylinder pressures greater than compression ratio times atmospheric pressure?
2) Does my engine look healthy to you guys, given that it was tested not cold, but pretty cool?
I did a compression test today on my 1995 4.0 with 233k miles. Engine had been driven about 3 hours before, so it was getting cool. My numbers were...
123
115
123
120
127
123
Some people were saying these are bare minimum- ready for a rebuild. However, I'm at nearly 6000', and it was a warm day. Altitude alone has a .836 correction factor, which would give me...
147
138
147
144
152
147
So, those alone bring me up to above my 137 theoretical max. Two questions:
1) How do you get cylinder pressures greater than compression ratio times atmospheric pressure?
2) Does my engine look healthy to you guys, given that it was tested not cold, but pretty cool?