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Pressure wave tuning

  1. Nov 21, 2003 #1
    I need some help.

    I would like to design a custom intake for a 8 cylinder IC engine.

    some back ground information.

    All cylinders are fed by a length of pipe with a tapering crossectional area (intake port). All 8 intake ports are connected to a common plenum.

    What I am trying to accomplish is to tune the pressure wave in the intake port to arrive at the intake valve at a pre determined moment. The reasoning is if the + pressure wave arrives at the valve just before the valve closes the momentum of the air will continue to flow into the cylinder aiding in volumetric efficiency.

    I am having a rough time developling an equation or method using crossectional area, varing crossectional areas, pipe length, and plenum volume to accurately predict the frequency of the + positive pressure wave.

    If I haven't given enough background information let me know or ask me what you need to know and I can go more indepth.

  2. jcsd
  3. Nov 22, 2003 #2


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    Many people have had a hard time developing such a formula. Most often, ram tuning is done experimentally with a good machine shop and a dyno.

    The formulas that do exist can be found in a book like "Internal Combustion Engine in Theory and Practice: (2 volumes) by Charles Fayette Taylor. Look for it at Amazon or other bookseller.
  4. Nov 22, 2003 #3
    Thanks Krab for you reply.

    I have about 15 ICE books. But if you notice they copy someone elses work majority are repeats of each other with slightly different spins on them. The formulas in the books are for four cylinders only. They don't tell you that in the books. I had to do some research to find out what size engine it was for.

    I know you could do it with a dyno and flowbenches and so on but it would be alot easier, cheaper and faster if I a had reasonable starting point.

  5. Nov 22, 2003 #4


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    There are lots and lots of books on the ICE. The vast majority have little or no physics in them, and as you note, they copy each other's formulas, and I'm guessing the authors don't really understand them. The book by Taylor is totally different; it is the only Academic book on ICE's I've run across. Look it up. It really is worthwhile.
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