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Thread: Compression ratio

  1. 10-09-2009, 01:14 PM #1
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    Default Compression ratio

    Is there a way i can calculate compression ratio from a kpa reading? I have about 1345 kpa on all cylinders.
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  2. 10-09-2009, 01:20 PM #2
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    wait.. what? No...?
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    Quote Originally Posted by lindsay.VS.Wagon. View Post
    ....a mini spool creates greater airflow to the engine which means more oxygen into the engine which adds greater combustion which adds an all around performance upgrade.
    Quote Originally Posted by edals View Post
    Also found running your lights all the time looses 100kms to a tank also.


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  3. 10-09-2009, 06:39 PM #3
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    9.4:1 is standard.

    what are you trying to work out? if ur has had work done or?
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    Quote Originally Posted by JEZIMP View Post
    jsut quickly, wat is a ffs search, ive seen it a fair bit and not sure wat it is, so some help would b greatly appreciated on where and how to do it, thankz
    Quote Originally Posted by vcstarfirequeen View Post
    its a 5 stud and u couldnt just weld a new stud on youd have to weld 5 new ones on i may be blonde but im not dumb

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  4. 10-09-2009, 07:00 PM #4
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    Yeah pretty much. Does anyone who knows their car is standard know their kpa reading?
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  5. 10-09-2009, 09:34 PM #5
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    how do you work out compression from a pressure test?
    The hall of fame:
    Quote Originally Posted by lindsay.VS.Wagon. View Post
    ....a mini spool creates greater airflow to the engine which means more oxygen into the engine which adds greater combustion which adds an all around performance upgrade.
    Quote Originally Posted by edals View Post
    Also found running your lights all the time looses 100kms to a tank also.


    ಠ_ಠ
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  6. 10-09-2009, 09:54 PM #6
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    you cant ......
    I tune the oldschool way fear on the passengers face and knuckle colour cant go wrong
    tabbacco is still my favorite vegetable
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  7. 10-09-2009, 10:25 PM #7
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    The book says "min cylinder compression pressure 689Kpa at 9.35 CR." That's less than half of what Maldotcom2 has!
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  8. 10-09-2009, 10:48 PM #8
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    hako, i have the same figures in my book, quite possibly comp has been raised. unless the gauge is screwed?!
    ------------------------------------------------------
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    Quote Originally Posted by JEZIMP View Post
    jsut quickly, wat is a ffs search, ive seen it a fair bit and not sure wat it is, so some help would b greatly appreciated on where and how to do it, thankz
    Quote Originally Posted by vcstarfirequeen View Post
    its a 5 stud and u couldnt just weld a new stud on youd have to weld 5 new ones on i may be blonde but im not dumb

    Wanted: VR/VS Standard Rear Bumper Bar - Can be damaged - PM me if you have one
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  9. 11-09-2009, 08:48 PM #9
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    Hako i read that part of the book too, hence why i'm asking. There are some online calculators to work it out but they required heaps of inputs like bore, stroke, etc. Thought someone might already know their figures so i can get an idea of whether it's normal or not.
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  10. 11-09-2009, 09:04 PM #10
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    that is the worst case reading for tired old engine needing repair ide say
    I tune the oldschool way fear on the passengers face and knuckle colour cant go wrong
    tabbacco is still my favorite vegetable
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  11. 11-09-2009, 09:06 PM #11
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    Some time ago, Greenfoam answered a query by calaiscruzer <<<My mate has a vn 304, running 10-1 compression.
    If we did a compression test, what should the results be around? >>>

    Greenfoam's reply:
    <<<About 170 at a guess, depending on what cam is in it (but a correct cam for 10:1 will be about 170)>>>


    Hope this helps.

    ps...that"s PSI....not Kpa!
    Last edited by hako; 11-09-2009 at 09:07 PM. Reason: ps
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  12. 12-09-2009, 12:57 AM #12
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    Yeah i get 195 PSI. Could it be compared to a 5L though?
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  13. 12-09-2009, 09:30 PM #13
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    a 5L has a compression ratio of 8.4:1

    cant find compression test info thou
    ------------------------------------------------------
    ------------------------------------------------------

    Quote Originally Posted by JEZIMP View Post
    jsut quickly, wat is a ffs search, ive seen it a fair bit and not sure wat it is, so some help would b greatly appreciated on where and how to do it, thankz
    Quote Originally Posted by vcstarfirequeen View Post
    its a 5 stud and u couldnt just weld a new stud on youd have to weld 5 new ones on i may be blonde but im not dumb

    Wanted: VR/VS Standard Rear Bumper Bar - Can be damaged - PM me if you have one
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