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Compression Ratio Formula:
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The compression ratio (CR) is a fundamental specification in internal combustion engines that represents the ratio of the maximum to minimum volume in the cylinder. It's calculated using the formula: CR = (Disp + V_c) / V_c, where Disp is displacement and V_c is clearance volume.
The calculator uses the compression ratio formula:
Where:
Explanation: The formula calculates how much the air-fuel mixture is compressed in the cylinder before ignition, which directly affects engine efficiency and performance.
Details: Compression ratio is critical for determining engine efficiency, power output, fuel requirements, and thermal efficiency. Higher compression ratios generally lead to better fuel economy but may require higher-octane fuels.
Tips: Enter displacement and clearance volume in cm³. Both values must be positive numbers. The result is a unitless ratio typically between 8:1 and 12:1 for most gasoline engines.
Q1: What is a typical compression ratio for gasoline engines?
A: Most modern gasoline engines have compression ratios between 8:1 and 12:1, with higher ratios found in performance and high-efficiency engines.
Q2: How does compression ratio affect engine performance?
A: Higher compression ratios generally increase thermal efficiency and power output but may require higher-octane fuel to prevent knocking.
Q3: What's the difference between static and dynamic compression ratio?
A: This calculator determines static compression ratio. Dynamic compression ratio accounts for valve timing and is typically lower than static compression ratio.
Q4: Can I use this calculator for diesel engines?
A: Yes, the formula works for both gasoline and diesel engines, though diesel engines typically have much higher compression ratios (14:1 to 25:1).
Q5: How does compression ratio relate to fuel octane requirements?
A: Higher compression ratios require higher octane fuels to prevent premature combustion (knocking or pinging) that can damage the engine.