Re: volvo compression test
Pressure(initial) = Pressure(ATM) + pressure(gauge) = 14.7 PSI. In this case, pressure(gauge) = 0 PSI
pressure(final) = pressure(ATM) + pressure(gauge) = 136 PSI. Since pressure final = 136, pressure gauge = 136-14.7 = 121.3 PSI.
Of course the presure final will be way higher that this because the temperature is not constant. By compressing the air, a lot of energy was introduced by the work necessary to compress the air. This causes the temperature to rise drastically and hence causes the pressure to rise.
This phenomenon is what cause air conditioning to work. Ever feel the output of a compressor? Pretty hot!
I can see how you guys thought it was 136. You were assuming Ideal Gas Law but forgot about temperature rise and how pressure(gauge) works.