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Compression Ratio

Compression ratio rk = (V_s + V_c) / V_c - dominant driver of Otto/Diesel cycle efficiency.

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Formula, assumptions, and limits

rk=Vs+VcVcr_k = \frac{V_s + V_c}{V_c}
SymbolMeaningUnit
VsV_sSwept volume = π/4·bore²·strokeL
VcV_cClearance volumeL
rkr_kCompression ratio

Source: Heywood - Internal Combustion Engine Fundamentals

In short

Compression ratio rk = (V_s + V_c) / V_c - dominant driver of Otto/Diesel cycle efficiency.

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