# Anatomy of a Combustion Engine (DD-334)

> In a four-stroke internal combustion engine, a piston draws in fuel and air, compresses it, and in gasoline engines a spark plug ignites it; diesel engines ignite the mixture by compression alone. The expanding gas pushes the piston down, turning the crankshaft, and the exhaust stroke clears the cylinder. The footage shows cutaway views of an engine and ignition in slow motion.

- Department: Tech
- First published: 2024-09-29
- Last updated: 2024-09-29
- Permalink: https://detailenjoyer.com/case/anatomy-of-a-combustion-engine/
- Author: Marcus Easterling (DetailEnjoyer), The Detail Department

## Quick facts

- **DD-334-F01**: Intake, compression, power, exhaust. _(Write-up · Exhibit A (Four strokes))_
- **DD-334-F02**: Gasoline engines use spark plugs. _(Write-up · Exhibit B (Spark))_

## Write-up

A car engine runs on thousands of tiny explosions a minute. The four-stroke cycle turns them into rotation.

1. **Four strokes**: Intake, compression, power, exhaust.
2. **Spark**: Gasoline engines use spark plugs.
3. **Diesel**: Diesels ignite by compression.
4. **Piston**: Gas pushes the piston.
5. **Crankshaft**: The crankshaft turns.

## Related case files

- [Full-Flow (DD-446)](https://detailenjoyer.com/case/full-flow/): I linked another engine cycle

## Reel vs. record

- **Note**: The Reel says a spark plug ignites the mixture; that is true for gasoline engines, while diesels ignite fuel by compression.

## Video: Anatomy of a Combustion Engine: A Car Engine Runs on Thousands of Tiny Explosions a Minute

- Duration: 27.1 s · Published: 2024-09-29
- File: https://detailenjoyer.com/assets/videos/DAhszy9p2VJ.mp4

### Transcript

Did you know, combustion engines work by burning fuel to produce mechanical energy. Inside the engine, a mixture of fuel and air is compressed in a cylinder. A spark plug ignites the mixture, causing a small explosion, which pushes the piston down. This movement turns the crankshaft, converting the energy from the explosion into rotational force. The process repeats rapidly, producing the power that drives the vehicle. Combustion engines typically run on gasoline or diesel, and rely on a cycle of intake, compression, combustion, and exhaust to keep functioning. NOW YOU KNOW!

## Questions & answers

**Q: Which stroke follows intake?**  
A: Squeeze. _(Source: Write-up · Exhibit A (Four strokes) · Wikipedia: Four-stroke engine)_

**Q: What ignites gasoline?**  
A: Electric spark. _(Source: Write-up · Exhibit B (Spark) · Wikipedia: Internal combustion engine)_

**Q: How do diesels ignite?**  
A: Hot air. _(Source: Write-up · Exhibit C (Diesel) · Wikipedia: Internal combustion engine)_

**Q: What does the piston turn?**  
A: Linear to rotary. _(Source: Write-up · Exhibit D (Piston) · Wikipedia: Internal combustion engine)_

**Q: How many strokes in the cycle?**  
A: Four-stroke. _(Source: Write-up · Exhibit E (Crankshaft) · Wikipedia: Internal combustion engine)_

## Sources

- [Wikipedia: Internal combustion engine](https://en.wikipedia.org/wiki/Internal_combustion_engine)
- [Wikipedia: Four-stroke engine](https://en.wikipedia.org/wiki/Four-stroke_engine)

## Cite this case file

Easterling, Marcus. "Anatomy of a Combustion Engine." The Detail Department (DetailEnjoyer), case file DD-334, last updated Sep 29, 2024. https://detailenjoyer.com/case/anatomy-of-a-combustion-engine/