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Unicorn :Compresion ratio [Update 1]

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  • Unicorn :Compresion ratio [Update 1]

    finally i have decided to try to increase compression ratio on my v1 uni and by the calculation and assumin the metal i m going to remove will result in volume change which would be equal to volume of cyllindrical shape of radius [bore\2] and length that i removed \ shaved from block .

    for 9.6 : 1 compression ratio the length i should remove came out to be .4 mm

    it is like

    SV = pi*(57.3\2)^2*57.8*(1/1000) = 149.05 cc

    default CR 9.1:1

    so CV = SV \ (9.1 - 1) = 18.4 cc

    now if i remove 0.4 mm from the block

    volume change = pi*(57.3\2)^2*0.4 *(1/1000) = 1.03 cc

    new CV = 18.4 - 1.03 cc = 17.37

    hence new CR
    (149.05/17.37)+1 = 9.58 : 1

    should i go ahead any other adjustment required?????

    and how much can i increase CR without worrying abt any thing!! max value??????

    UPDATE 1:
    Compression ratio mod is complete , sattled for 10.1:1

    Last edited by viv.nomad; 06-09-2009, 02:19 AM.
    https://antibiotiqueaugmentin.com/

  • #2
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    • #3
      Originally posted by viv.nomad View Post
      how much can i increase CR without worrying abt any thing!! max value??????
      Just make sure that the engine is not knocking and valves do not bang into the piston. You can increase the CR to that limit.
      Your biking tells a lot about the person you are!

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      • #4
        u sure??

        share some exp!!
        https://antibiotiqueaugmentin.com/

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        • #5
          I do not have any practical experience dude. But, AFAIK these are the two factors that limit the compression ratio. Maybe others with practical experiences can confirm.

          And your calculations are correct!
          Your biking tells a lot about the person you are!

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          • #6
            that are max physical borders.. i was talking abt limit where only increasing CR will give performance and it may not involve other component adjustment like valves..
            https://antibiotiqueaugmentin.com/

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            • #7
              Originally posted by viv.nomad View Post
              that are max physical borders.. i was talking abt limit where only increasing CR will give performance and it may not involve other component adjustment like valves..
              Increasing your CR up to these physical limits will improve performance irrespective of any changes in the valve timings. However, after a certain point, ignition timings will need to be changed to allow further increase of CR till the limits.
              Your biking tells a lot about the person you are!

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              • #8
                woich to .. are bhai kab ignition timing change karne ki jururat padti hai.... kis CR k baad..
                https://antibiotiqueaugmentin.com/

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                • #9
                  Originally posted by viv.nomad View Post
                  woich to .. are bhai kab ignition timing change karne ki jururat padti hai....
                  That depends on how the bike is currently set up. I do not have any idea about the unicorn. If ignition timings are not retarded, knocking may occur.

                  You can do one thing - go ahead and shave the 0.4mm from the head. If knocking occurs you will have two choices - use double head gasket to decrease the CR a bit, or use high octane petrol.

                  If everything is fine, go ahead and shave a bit more. If knocking occurs again use double head gasket or high octane fuel.

                  So, the idea is to discover the limit of your bike with the current timings.
                  Your biking tells a lot about the person you are!

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                  • #10
                    you'll come to know when your engine knocks

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                    • #11
                      Originally posted by abhijeet080808 View Post
                      That depends on how the bike is currently set up. I do not have any idea about the unicorn. If ignition timings are not retarded, knocking may occur.

                      You can do one thing - go ahead and shave the 0.4mm from the head. If knocking occurs you will have two choices - use double head gasket to decrease the CR a bit, or use high octane petrol.

                      If everything is fine, go ahead and shave a bit more. If knocking occurs again use double head gasket or high octane fuel.

                      So, the idea is to discover the limit of your bike with the current timings.
                      yes that i want ..the limit with stock ignition timings.. the workshop where i'll be carrying out this stuff has accuracy of 0.02 mm , he charging 250 Rs for 1 shaving!! then i need to take iterations and so consider total amt spent too .. more over if some bad happens then i'll have buy new head , which i want to avoid at all the cost!!

                      Originally posted by k_tornado_sj View Post
                      you'll come to know when your engine knocks
                      comon man knocking is so common!! run ur bike in very hot temp outside it will knock even at 80 kmph!!
                      but this time knocking is actually going to be very stronger in noobs term [me].. so is the possible damage!!



                      note: i found a formula and the torque increase due to CR is very demoralizing only 0.3 Nm of gain!!
                      Last edited by viv.nomad; 06-07-2009, 01:03 PM.
                      https://antibiotiqueaugmentin.com/

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                      • #12
                        suggestion

                        viv.namad : Mill off 0.2 mm instead of 0.4mm and use thinner gasket....just a suggestion....so if there is any problem you can revert back to original state using slightly thicker gasket.

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                        • #13
                          Originally posted by vipin_s View Post
                          viv.namad : Mill off 0.2 mm instead of 0.4mm and use thinner gasket....just a suggestion....so if there is any problem you can revert back to original state using slightly thicker gasket.
                          what this gasket is made of ; ruber Cu , Al ?????/
                          https://antibiotiqueaugmentin.com/

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                          • #14
                            ^^ No metals for sure...mostly asbestos or fiber-reinforced paper-like material or ground cork/rubber....they use proprietory adheshives (like Loctite) to bond gasket with the block.

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                            • #15
                              head gasket is made of some metal....there is not much u can choose like thin and thick gasket..its only 1 or 2...as far as i heard from joel is upto 0.5mm,no frills it will run properly with a small bump in perf...so dont worry go in for the mod and do post the results...if possible jus make a note of the time reqd for 0 to 60,top speed and speeds in each gear in stock form..
                              so it would be easy for u to gauge the increase in the power and by the way ru running on xtreme cam shaft or still on the stock cam...

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