Four-stroke engine cycle — correct chronological sequence of strokes Identify the correct order of the four strokes in a conventional four-stroke internal combustion engine.

Introduction / Context:
The four-stroke cycle is the foundation of most automotive engines. Understanding the correct sequence is essential for diagnostics (e.g., valve timing, misfire analysis) and general engine theory.

Given Data / Assumptions:

• Naturally aspirated or boosted engines still follow the same stroke order.
• Terminology: suction = intake, power = expansion.
• Valves open/close according to cam timing over crankshaft rotation.

Concept / Approach:
The cycle comprises four distinct piston strokes over two crankshaft revolutions: intake (charge enters), compression (mixture compressed), power (combustion and expansion do work), and exhaust (spent gases expelled). The ignition event occurs near the end of compression for SI engines (spark) and by auto-ignition for CI engines (diesel).

Step-by-Step Solution:

Verification / Alternative check:
Animation or timing diagrams in service manuals show valve events aligned with the above sequence; crank rotates 720 degrees per full cycle.

Why Other Options Are Wrong:

• Sequences mixing exhaust or power out of order violate thermodynamic and mechanical timing.
• Any order not starting with intake then compression is inconsistent with standard valve timing.

Common Pitfalls:
Confusing two-stroke processes with four-stroke; mixing terminology (suction vs. intake, power vs. expansion).

Final Answer: