Miller Cycle vs Beau de Rochas (Otto) Engine Cycle Diagram – Mazda MX-3 Reference

This French-language schematic compares the operating phases of two internal combustion engine cycles. The upper panel, titled "Moteur à cycle Beau de Rochas" (Beau de Rochas / Otto cycle engine), shows four cutaway piston-and-crankshaft diagrams labeled Admission (intake), Compression, Explosion (power/combustion), and Echappement (exhaust). The lower panel, titled "Moteur à cycle Miller" (Miller cycle engine), shows five diagrams labeled Admission, Pas de compression (no compression — the phase where the intake valve remains open as the piston begins rising, so no compression occurs), Compression, Explosion, and Echappement. Each diagram depicts a spark plug, intake and exhaust valves, piston position, connecting rod, and crankshaft rotation direction, with arrows showing gas flow into or out of the cylinder and piston travel. Dimension arrows alongside the cylinders indicate the effective stroke or compression height in each phase, visually emphasizing that the Miller cycle's effective compression stroke is shorter than its expansion stroke. A reader can learn the sequence of events in a conventional four-stroke cycle versus a Miller cycle and see graphically why the Miller cycle delays compression via extended intake valve opening. No part numbers, years, or vehicle model information appear in the document.