Engineering English
Compression Ratio
Mechanical Engineering · Last updated: July 30, 2026 · How this entry was written
Definition: Compression ratio is the ratio of the maximum volume of a cylinder to the minimum volume when the piston is at top dead center. It directly affects the thermal efficiency of internal combustion engines and is critical for performance and knock resistance.
Example in context
“Increasing the compression ratio from 8.5:1 to 10.5:1 improved the engine's brake thermal efficiency by 3% but required higher octane fuel to prevent knocking.”
“Sıkıştırma oranını 8.5:1'den 10.5:1'e çıkarmak motorun fren termal verimini %3 artırdı ancak vuruntuyu önlemek için daha yüksek oktanlı yakıt gerektirdi.”
Where engineers use it
In internal combustion engine design, the compression ratio is a fundamental parameter that determines thermal efficiency, power output, and risk of engine knock. Engineers adjust it when developing high-performance or fuel-efficient engines, and it is reported in technical datasheets and simulation models.
Practice: can you use “Compression Ratio” at work?
A customer requests a redesign of a gasoline engine to run on a fuel with lower octane rating. You must evaluate the maximum safe compression ratio that avoids knock while maintaining power targets.
Show a model answer
“What is the compression ratio of this engine and how does it affect efficiency?”
“Compression Ratio” in 21 languages
| English | Compression Ratio |
|---|---|
| Turkish | sıkıştırma oranı |
| French | taux de compression |
| German | Verdichtungsverhältnis |
| Spanish | relación de compresión |
| Chinese | 压缩比 |
| Arabic | نسبة الانضغاط |
| Portuguese | taxa de compressão |
| Russian | степень сжатия |
| Japanese | 圧縮比 |
| Italian | rapporto di compressione |
| Vietnamese | tỉ số nén |
| Hindi | संपीड़न अनुपात |
| Thai | อัตราส่วนกำลังอัด |
| Indonesian | rasio kompresi |
| Korean | 압축비 |
| Bengali | সংকোচন অনুপাত |
| Dutch | compressieverhouding |
| Swedish | kompressionsförhållande |
| Finnish | puristussuhde |
| Ukrainian | ступінь стиснення |
Frequently asked questions
What does Compression Ratio mean in engineering?
Compression ratio is the ratio of the maximum volume of a cylinder to the minimum volume when the piston is at top dead center. It directly affects the thermal efficiency of internal combustion engines and is critical for performance and knock resistance. In Mechanical Engineering, the term carries a usage-frequency rating of 10/10 in the Engineering English library.
How do you pronounce Compression Ratio?
Compression Ratio is pronounced /kəmˈprɛʃən ˈreɪʃioʊ/ (IPA). The Engineering English app plays audio for the term and checks your pronunciation with speech recognition.
How is Compression Ratio used in a sentence?
Example from an engineering context: “Increasing the compression ratio from 8.5:1 to 10.5:1 improved the engine's brake thermal efficiency by 3% but required higher octane fuel to prevent knocking.”
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