1. Crankcase: The housing that encloses the crankshaft and other lower engine components. It holds the oil and often includes the oil pan.
2. Cylinder Block: The main structural element of the engine, containing the cylinders where combustion occurs. It's often made of cast iron or aluminum.
3. Cylinders: The individual chambers where the pistons move up and down.
4. Pistons: Moving components within the cylinders that are driven by the expanding gases of combustion.
5. Piston Rings: Metal rings fitted around the piston that seal the combustion chamber and prevent oil from entering it.
6. Connecting Rods: Connect the pistons to the crankshaft, transferring the piston's reciprocating motion to rotational motion.
7. Crankshaft: The rotating shaft that converts the reciprocating motion of the pistons into rotational power, which drives the vehicle.
8. Flywheel: A heavy rotating disc attached to the crankshaft that smooths out the engine's power delivery and helps with starting.
9. Valves: (Intake and Exhaust) Control the flow of air and exhaust gases into and out of the cylinders.
10. Camshaft: A rotating shaft that opens and closes the valves at precisely timed intervals.
11. Valve Springs: Return the valves to their closed position after they are opened by the camshaft.
12. Timing Belt/Chain: Synchronizes the rotation of the crankshaft and camshaft, ensuring the valves open and close at the correct times.
13. Head Gasket: A seal between the cylinder head and the cylinder block, preventing leaks of coolant and combustion gases.
14. Cylinder Head: The top part of the engine that houses the valves, camshaft, and spark plugs (or glow plugs in diesel engines).
15. Spark Plugs/Glow Plugs: Ignite the air-fuel mixture in gasoline engines (spark plugs) or preheat the air-fuel mixture in diesel engines (glow plugs).
16. Carburetor/Fuel Injectors: Meter and deliver fuel to the cylinders. Modern engines primarily use fuel injectors.
17. Oil Pump: Circulates engine oil to lubricate moving parts.
18. Oil Filter: Removes contaminants from the engine oil.
19. Ignition System: (In gasoline engines) Provides the high voltage spark needed to ignite the air-fuel mixture.
20. Cooling System: Includes the radiator, water pump, thermostat, and coolant, to regulate the engine's temperature.
This is not an exhaustive list, as many other smaller components and sensors are also crucial to the engine's operation. The specifics can also vary depending on the type of engine (gasoline, diesel, rotary, etc.).
