| 摘要 |
A series of four-stroke engine manifolds for providing improved power and torque over a wide range of engine speeds are described. A two-mode two degree-of-freedom resonator model for manifolds is described that predicts two individual torque peaks. The model is shown to be valid only when two described dimensionless parameters, computer from the dimensions of the manifold and the engine to which it is attached, have minimum values. If the two minimum values are not maintained, the correct resonator model collapses to a one degree-of-freedom system which provides only one, generally lower, torque peak. By requiring minimum values for the two parameters, the resulting manifolds provide the desired improved power and torque. The manifolds comprises two, three or four primary runners each connected at first ends to an engine cylinder and together at second ends to a secondary runner. A primary volume is defined as the volume of an engine cylinder with its piston at midstroke. A secondary volume is defined as the total volume of all primary runners, other than a primary runner attached to a first cylinder, and all cylinder intake ports, other than the intake port for the first cylinder. The manifold dimensions are limited so that the runner coefficient, the ratio of the length-to-area ratio of the secondary runner divided by the length-to-area ratio of any primary runner, is at least 0.15; and, so that the volume coefficient, the ratio of the secondary volume divided by the primary volume is at least 2.0.
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