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Valve spring

  1. Sep 23, 2007 #1
    Hi guys, i am doing some calculations on the valve spring of a 4 stroke, 4 cylinder motor vehicle engine.

    To my understanding, valve bounce will occur once the valve spring is operated at a speed over their natural frequency (which i calculated to be 5500 rev/min). If i were to push the engine speed to 8000 rpm, does it mean that the valve spring won't 'bounce' since the camshaft only runs at half the engine speed? But if that was the case, why do most vehicle have red lines at 6500rpm on the rev counter? Is it really neccessary to have such large safety factor?

    Thanks
     
  2. jcsd
  3. Sep 23, 2007 #2
    But if the torsonial stress that doesn't bypass the force required to sustain the engine running at that speed, what is the correlation between engine speed (esp at high values of 8000rpm) to the average rev?
     
  4. Sep 23, 2007 #3

    dlgoff

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    "... why do most vehicle have red lines at 6500rpm on the rev counter? Is it really neccessary to have such large safety factor?"

    Maybe it's for a different reason than the valves "floating".
     
  5. Sep 25, 2007 #4
    I think you are putting more stress(and heat of course) on the valve springs/valves....with more rpm.....so keep that in mind. They are designed and made from material which will only withstand a certain force/stress/strain. This is why you will usually break a spring, or drop a valve
     
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