Here's why:
* Standard Engine Cycles: Engines operate on cycles, typically either 2-stroke or 4-stroke. These cycles define the sequence of intake, compression, combustion, and exhaust.
* Efficiency and Complexity: Adding more strokes would introduce significant mechanical complexity and might not offer a substantial gain in efficiency or power.
* Theoretical Concepts: Some theoretical engine concepts have been proposed that go beyond the standard 4-stroke cycle, but these are highly experimental and not currently used in practical applications.
If you've encountered the term "8-stroke engine," it's likely a misunderstanding or a fictional concept.