What if I told you there was an engine with no valves at all? The sleeve valve engine from the early 1900s used moving sleeves instead of traditional valves to control airflow. This revolutionary design ran smoother, quieter and more efficiently than regular engines. But here's the catch. It was so complex and expensive to manufacture that it disappeared from the market. Today, engineers still debate whether we gave up on this brilliant technology too early. Imagine if we had perfected it instea