 A longer inlet pipe will create a later intake pressure wave that will help keep the air in the chamber until the intake valve closes.The acceleration of air flow into a duct is inherently a highly efficient process and the difference between even the crudest radius inlet, and the most aerodynamic shape possible is slight, amounting to no more than a few percent.The flow coefficient of a perfect entry would be 1.0 while the coefficient for a sharp edged entry would be 0.6 and a re-entrant plain pipe 0.5.