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Sambar EN07 - compression?

Discussion in 'Subaru Sambar' started by Andrew.r.w, Jun 4, 2011.

  1. Andrew.r.w

    Andrew.r.w Member

    What should the compression be for my 1992 Sambar EN07? PSI and ratio if known plz. The manual says 9.8 but there is no unit. I doubt if that is PSI ..
     
  2. fupabox

    fupabox Active Member

    that's 9.8 bar about 143psi and correct according to my figures
     
  3. Andrew.r.w

    Andrew.r.w Member

    Thanks fupabox. Another quick and to-the-point reply - much appreciated.

    That is higher than I expected. I would have guessed PSI to be around 110 given the high RPM of these engines. I'm going to do a compression test to see if I can gather enough justification to do an engine job this summer.
     
  4. fupabox

    fupabox Active Member

    your compression ratio and cylinder compression are related..if you know one you can find the other

    psi = bar X 14.5
    1 bar is 1 atmosphere or a compression ratio of 1 to 1
    compression of 8 to 1 is 8 atmospheres or 8 x 14.5 = 116psi
    I'm not sure how heat is added to these calculations to determine true operating psi,but it is a good benchmark to check engine compression if you know the C.R.


    On another note...while double checking the compression ratios on the EN07 I found an article from Japan stating that Subaru will stop making commercial minis in 2012...no more Sambar ?...could have been a result of a bad translation though
     
    Last edited: Jun 5, 2011
  5. minitruck.ca

    minitruck.ca Gold Supporting Member

    Subaru Sambar Parts

    We stock rings, Gaskets, Bearings etc if you need to rebuild your Sambar Engine
     
  6. JoeBean

    JoeBean New Member

    I realize this is an old post but searching for some info on my engine leads here and since this info is incorrect I wanted to add some clarification for those who might end up here in the future:

    The 9.8 in the manual is for compression ratio (CR), not cylinder pressure (CP) that you'd check with a compression gauge. That is to say, the carbureted EN07's cylinder volume with the piston fully retracted vs fully extended is 9.8:1. In the supercharged Y that I have it's 8.3:1. It's unitless because it's just a ratio - it's not in bars.

    There is no direct relationship between CR and CP. You can't calculate CP without more engine data, though according to wikipedia (ie. take this with a grain of salt) it's between 15 and 20 times the CR. In actuality that's not really all that accurate (and it would be useless as well since the range would be huge) as engine design makes a huge difference from engine to engine.

    Subaru doesn't specify CP. Many automakers don't anymore as it's not a very accurate way of determining engine health. It can be helpful to identify a problem cylinder by comparing the values from one cylinder to another. 10% variance is usually considered tolerable. Much variation (up or down) usually means a problem.

    But to get a better idea of engine health you can get a leak-down tester and check to see where you're losing air from. That can help repairs too as it's much easier and cheaper to repair a valve that's not seating correctly than completely rebuild the engine. Also, a cheap endoscope will let you see inside the cylinders so you can check for scoring and wear.
     
  7. Rcooper917

    Rcooper917 Member

    My Sambar is pushing 180psi
     
  8. Rcooper917

    Rcooper917 Member

    What did you end up with Andrew? My ran 180 + psi across the board with small fluctuations of a few pounds.
     

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