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Finding out the time duration for which intake valve remains open

  1. Mar 5, 2012 #1
    I set out to find out how many seconds it takes for a 4cylinder naturally aspirated diesel engine to complete 1 cycle(4 strokes):
    I considered a tata indica model
    max power:53.5PS@5000rpm

    therefore 5000 rev per min or 83.3 rev per sec
    now it takes 0.012 seconds to complete 4 strokes or 1 cycle and 6x10^-3 seconds for 2 strokes

    Now I want to find how much time does the intake valve remain open.
  2. jcsd
  3. Mar 6, 2012 #2
    That is impossible to know with out knowing the exact camshaft specs.
  4. Mar 6, 2012 #3
    you mean to say the crank angles at which the valves operate ..now if i know the time
    duration for the intake stroke can i not find out the valve open duration..in seconds?
  5. Mar 6, 2012 #4
  6. Mar 6, 2012 #5
    About 0.006 seconds, assuming 180 open duration out of the 720 degrees needed to complete one cycle (0.024 sec., not 0.012).

    It sounds like you're assuming that the intake opens exactly at TDC and closes at BDC; not so. As mentioned, the intake opening and closing points will depend on the design specs of the camshaft.
  7. Mar 17, 2012 #6


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    The whole point is racing cam design is to get maximum open time while still getting the valve securely seated in time to prevent blow back when ignition begins. Lots of effort goes into cam design, and as a result, the performance with each cam will be different. Measuring this in a running engine is going to be extremely difficult. You would be much better off to get the cam profile and then work through the kinematics of the valve gear in order to predict the valve open time.
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