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coaxial dual-poppet valves

Earlier opening allows longer valve duration
  [vote for,

Take a standard intake valve, cut four holes through the sealing end, and put a smaller valve inside the big one. Now you have the smaller valve opening first, allowing some air in through the four holes, and then the bigger valve opening later allowing the rest of the air in. This solves the problem of interfering valve design, where you can't open a valve too early or it will hit the piston. A way to get more air into the chamber at high RPM.
bagpipey1234, Dec 21 2004


       Yes, it's all about the valves. I weld them tight in my engine design at Horible Terrible Ice-Bots, recent submission.
mensmaximus, Dec 21 2004

       Unless you have a blower or pressure from a tuned intake no air is trying to get past the valve before or near top dead center. Opening before top dead center is done to give the valve a "head start" so it will be more open when air must pass through it. It's less wear and tear on the machinery to give the valve a little head start instead of forcing the valves open and shut faster with more aggressive cam profiles.
hangingchad, Dec 23 2004


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