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Understanding the different units of engine power measurement – HP, kW, PS and USHP

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    Understanding the different units of engine power measurement – HP, kW, PS and USHP

    Understanding the different units of engine power measurement – HP, kW, PS and USHP

    While the term “horsepower” is widely known for describing or measuring how powerful an engine is, there are several different units of power measurement in use around the world, which despite having similar or even the same names, are actually not the same or equal units, which has often lead to confusion when attempting to compare these measurements to each other.

    The most commonly used units of measurement for engine power are;

    Kilowatts, or kW, mostly used in the Southern Hemisphere
    Pferdestärke, or PS, primarily used in the European Union, but often referred to as Horsepower, or HP
    United States Horsepower, or USHP, which confusingly is often referred to simply as Horsepower, or HP
    Horsepower, or HP, both a unit of measurement, also a generic term, also often used to describe PS or USHP

    So what’s the confusion?

    European auto manufacturers typically state their engine power in PS, but as that is essentially an abbreviation of a German-language word, when documentation is translated to English, or a vehicle is marketed outside of the EU, the PS number is often directly applied without conversion to a HP number, however 1PS = 0.98632HP, which is a small discrepancy, but a discrepancy nonetheless.

    The kW has very limited use and acceptance outside of the Southern Hemisphere as a unit of engine power. Through the complexity of the SI system, Kilowatts are also a unit of electrical power, which does not help with the acceptance or understanding of kW as a unit of engine power. 1kW = 1.35962PS, and 1kW = 1.34102HP

    HP as a unit of measurement, is 1HP = 1.01387PS, and 1HP = 0.7457kW, but when the term HP is applied generically to describe power in PS or USHP, it is no longer an accurate representation of engine power.

    USHP originated in the United States, hence the US, but over time, through the internet and instant global communication, its use has spread widely around the globe. Although often perceived as a unit of measurement, USHP can best be described as a variable, as there is no fixed conversion factor of USHP to kW, PS or HP.

    The convention of shortening the unit “USHP” to simply “HP” in written and oral communication leads to further confusion, since 1USHP is never equal to 1HP. In most cases it’s possible to determine if the power described is USHP or HP from the geographical source of the given measurement; if the source is located within North America it will most likely be a figure in USHP, even though it is reported as HP. If the source is outside of North America, then further assessment may be required to determine the actual units being used.

    Attempting to establish an approximate conversion of USHP to HP can be problematic, since the USHP is indeed a variable, and there are many factors that influence the final numbers presented as a measurement.

    A comparative survey of published dynamometer results from North America (confirmed to be USHP), compared to those from Australia, Germany and the United Kingdom, (confirmed to be HP), for comparable engines and vehicles, in both modified and un-modified states, has shown a considerably wide range of variation. Whilst it is difficult to plot a trend that encompasses all influencing factors, variations as slight as 1USHP = 0.96HP, right up to 1USHP = 0.68HP, have been observed.

    The convention of USHP being incorrectly reported as HP, will undoubtedly continue to cause confusion for the foreseeable future.
    Jaguar XJR, Freelander 2 HSE, Jaguar XKR, MINI Cooper S
    Originally posted by nutttr
    People must assume you are some sort of drug dealer with all these nice cars turning up to a fibro home

    #2
    BHP?

    Comment


      #3
      Shots fired!
      Previously known as Lobster, Chuss's brother's anus, Chuss's brother, Lobsook, Lobstersock, Socks, Sockz, MissAmericaImportGirl, ClutchCLobster

      CJM 4 Life yo!

      Comment


        #4
        Originally posted by mizone View Post
        BHP?
        what Broken Hill Proprietary
        you cant spell advertisements without semen between the tits

        Comment


          #5
          Bloody Hot Pipe

          I thought PS stood for Power Stroke

          Comment


            #6
            Originally posted by Ribfeast View Post
            I thought PS stood for Power Stroke
            I think the direct translation if you split the word up into it's two components is "horse strength" … but Google Translate gives me "horsepower" if I translate the typically-mooshed-together German word.
            It's also referred to as "metric horsepower" innit?

            USHP = Pub HP ==> USA is a pub?
            Soft roaders represent an excellent compromise between the needs of the hardcore 4x4 user and the convenience of a city hatchback. Its clear to see why they have become so popular in todays society.

            Comment


              #7
              No. Its Pferdestrke. Or horse strength.

              Powerstroke is the name Ford give there V8T Diesel engines originally made by International.
              Last edited by bigshipengine.jpg; 30-09-19, 12:06 PM.
              I climbed Mt Druitt

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                #8
                Originally posted by Ribfeast View Post
                I thought PS stood for Power Stroke
                Time to go back through your old Zoom magazines!
                Originally posted by Marlin
                Chickens will slip under water in the cover of darkness like a seal team and FUCK YOU UP.

                Comment


                  #9
                  So a horse is what the English use when their electrics fail and they need to move their car? So if a Landrover looses it's Lucas ghostwind it's going to take 60 horses to get it back to where it came from? Hence Broken Horse Power. No wait. umm..

                  American horsepower is a fictional indication of what the owner thinks a car is capable of making when torque is multiplied by a variable.

                  Right?

                  Comment


                    #10
                    Originally posted by mizone View Post
                    American horsepower is a fictional indication of what the owner thinks a car is capable of making when torque is multiplied by a variable.

                    Right?
                    Similar to internet horsepower I think - round up the dyno figure to the nearest 100 then add 60.

                    Comment


                      #11
                      USHP starts at about 800 these days

                      Comment


                        #12
                        Also multiply by a factor of Shootout Mode.
                        Originally posted by brewdles
                        In short, some cunt at test and tune had a 250cc honda turning to 11ty and it sounded porn. Do that.

                        Comment


                          #13
                          How many duckpower is that?

                          Comment


                            #14
                            What ever happened to Llama thrusts?

                            Comment


                              #15
                              Rwushp is always about 1000 give or give

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