四衝程汽油引擎進氣氣道之良窳，對容積效率具有決定性影響，而容積效率則影響到引擎的出力。車輛界常使用穩流狀態下之流量試驗，量測進氣氣道之質量流量及計算流量係數(Flow Coefficient)，作為評估進氣氣道是否符合設定目標。進氣氣道之開發流程，係參酌經驗或設計準則，設計2D 圖面及3D 模型、製作流量盒(Flow Box)、進行穩流狀態下之流量試驗、修改流量盒再進行流量試驗，一直到符合所設定之流量係數目標，再將此一最終之流量盒作為產品開發用途。本文嘗試運用逆向工程技術以輔助或改善進氣氣道開發流程中之某些作法，以期達到更快速及精確地開發新產品與改良既有之產品，並將開發過程相關資料回饋至原有CAD 模型，改善整體進氣氣道之開發流程。 The performance of the inlet port in four stroke gasoline engine has great influence on the volumetric efficiency which affects the output of the engine. It is often in the automotive industry to perform a steady state flow test across the inlet port to acquire the actual mass flow rate and calculate the flow coefficient to evaluate whether the inlet port design meets the pre-defined requirement or not. By following the development procedure of the inlet port, some design guidelines as well as engineer’s experience are used to conduct the 2D inlet port design and its 3D model. A flow box is then manufactured to perform a trial and error test on the steady-state flow bench until the pre-defined target is achieved. The improved flow box is then used to go through the rest of the product development process. The objective of this research is to apply the technology of reverse engineering to assist or improve the inlet port development tasks, and hopefully, to make the product modification and development more precisely and quickly. The modified data of the inlet port could be feedback to the original CAD model so that the entire port development process can be improved.