State any 2 reasons for using ethyl alcohol as a SI engine fuel.

 Here are two key reasons for using ethyl alcohol (ethanol) as a fuel in SI (Spark Ignition) engines:

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✅ 1. High Octane Number

• Ethanol has a high octane rating (≈ 108), which allows it to resist engine knock (pre-ignition or detonation).

• This enables higher compression ratios in SI engines, leading to better efficiency and performance.

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✅ 2. Renewable and Cleaner Burning

• Ethanol is a renewable biofuel, typically produced from crops like sugarcane or corn.

• It burns cleaner than gasoline, producing less CO and unburnt hydrocarbons, and lower net CO₂ emissions (due to carbon neutrality from plant sources).

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✳️ Bonus Benefits:

• Provides cooling effect due to high latent heat of vaporization.

• Can be blended with gasoline (e.g., E10, E85) to reduce petroleum consumption.

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Ethanol is increasingly used in modern SI engines, especially in flex-fuel vehicles and biofuel initiatives for sustainable energy.