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volvo compression test

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  • volvo compression test

    Does anyone know what a good result is from a compression test on a 1983 Volvo AQ125A?

    I'm planning on testing it this weekend but don't know what range I should be in.

    Thanks


  • #2
    Re: volvo compression test

    The book calls for 9.3:1 compression ratio and between 146-174 psi.
    75 Glastron V-179
    AQ130C

    Comment



    • #3
      Re: volvo compression test

      FWIW 9.3:1 compression = 136 psi
      Just owning a boat does not make you a boater!!

      " Life is so much better on a boat " SS MAYFLOAT

      "All that is necessary for evil to win the world is for good men to do......................nothing" Edmund Burke

      "A simple way to take measure of a country is to look at how many want in, and how many want to get out." Prime Minister Tony Blair

      Page 2,
      Class of '05



      Comment



      • #4
        Re: volvo compression test

        FWIW...it is more than 136psi.

        You can't calculate the pressure just by the change in volume. You have to take into account energy introduced. This also increases the pressure.
        1998 Wellcraft Eclipse 24 Cuddy
        Volvo Penta Duo-Prop 7.4L "LK"

        2006 Sun Tracker Party Barge 21
        Mercury 90 4-Stroke FI
        "Common sense is not very common"
        "Failing to prepare is preparing to fail." -- John Wooden

        Comment



        • #5
          Re: volvo compression test

          [colour=blue]
          Originally posted by Limited-Time
          FWIW 9.3:1 compression = 136 psi
          In a perfect world - yes. But there are way to many variables to nail down an exact correlation.

          Rubberduck, taking into account the age, a good result would be around 140-150 with no more than 5% variation.

          Watch this space......................

          Comment



          • #6
            Re: volvo compression test

            Curious how you think 136 PSI in a perfect world.
            1998 Wellcraft Eclipse 24 Cuddy
            Volvo Penta Duo-Prop 7.4L "LK"

            2006 Sun Tracker Party Barge 21
            Mercury 90 4-Stroke FI
            "Common sense is not very common"
            "Failing to prepare is preparing to fail." -- John Wooden

            Comment



            • #7
              Re: volvo compression test

              [colour=blue]14.7 x 9.3 = 136.71.

              Maybe I should have said 'theoretical' world.
              Watch this space......................

              Comment



              • #8
                Re: volvo compression test

                Originally posted by bruceb58
                Curious how you think 136 PSI in a perfect world.
                Atmospheric pressure = 14.695 PSI,(at sea level) 14.7 X 9.3= 136.6 PSI

                Just owning a boat does not make you a boater!!

                " Life is so much better on a boat " SS MAYFLOAT

                "All that is necessary for evil to win the world is for good men to do......................nothing" Edmund Burke

                "A simple way to take measure of a country is to look at how many want in, and how many want to get out." Prime Minister Tony Blair

                Page 2,
                Class of '05



                Comment



                • #9
                  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.
                  1998 Wellcraft Eclipse 24 Cuddy
                  Volvo Penta Duo-Prop 7.4L "LK"

                  2006 Sun Tracker Party Barge 21
                  Mercury 90 4-Stroke FI
                  "Common sense is not very common"
                  "Failing to prepare is preparing to fail." -- John Wooden

                  Comment



                  • #10
                    Re: volvo compression test

                    That's why the dreaded SERVICE MANUAL that most people seem to really hate to own, says 146-174 psi.
                    Don S.

                    sigpic

                    Please, no PM's (Private Messages) regarding boat/engine problems.
                    That is what the forums are for.
                    Only forum/moderator issues will be answered in PM's.

                    Comment



                    • #11
                      Re: volvo compression test

                      yeah...I bet the Clymer manual says 136.
                      1998 Wellcraft Eclipse 24 Cuddy
                      Volvo Penta Duo-Prop 7.4L "LK"

                      2006 Sun Tracker Party Barge 21
                      Mercury 90 4-Stroke FI
                      "Common sense is not very common"
                      "Failing to prepare is preparing to fail." -- John Wooden

                      Comment



                      • #12
                        Re: volvo compression test

                        More likely it says 631 :devil:
                        Don S.

                        sigpic

                        Please, no PM's (Private Messages) regarding boat/engine problems.
                        That is what the forums are for.
                        Only forum/moderator issues will be answered in PM's.

                        Comment



                        • #13
                          Re: volvo compression test

                          [colour=blue]I didn't say it was 136.

                          If you read the posts - we all agree. But it seems we must have a maths lesson from Bruce and a shot across the bow from Don to end the thread.
                          Watch this space......................

                          Comment



                          • #14
                            Re: volvo compression test

                            it wasn't a math lesson...it was a thermodynamics/chemistry lesson!

                            I just wanted people to realize you cant just multiply the atmospheric pressure times the compression ratio to get the pressure.
                            1998 Wellcraft Eclipse 24 Cuddy
                            Volvo Penta Duo-Prop 7.4L "LK"

                            2006 Sun Tracker Party Barge 21
                            Mercury 90 4-Stroke FI
                            "Common sense is not very common"
                            "Failing to prepare is preparing to fail." -- John Wooden

                            Comment



                            • #15
                              Re: volvo compression test

                              My money is on Don he's rarely wrong no offense guys..........
                              Stickly a opinion your milage may vary.

                              Speed is how fast you hit the wall
                              Torque is how far you move the wall"

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