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Fuel Octane Calculator

Determine the required fuel octane for your engine based on compression ratio, timing, and other factors. Prevent detonation and optimize performance.

Octane requirements No data stored Mobile friendly
91 Required Octane

Fuel Octane Calculator

Units

Engine Specifications

Static or dynamic compression ratio
Type of compression ratio entered
Total ignition advance at WOT
Type of engine induction

Environmental Factors

Elevation above sea level
Outside air temperature
Relative humidity percentage

Performance Factors

Forced induction boost pressure (0 for NA)
Quality of available fuel
Safety margin for octane requirements

What is Octane Rating?

Octane rating measures a fuel's resistance to detonation (knocking). Higher octane fuels can withstand higher compression and advanced timing without detonating.

Common Ratings: 87 (Regular), 91-93 (Premium), 100+ (Race)

Detonation vs Pre-ignition

Detonation occurs when fuel ignites spontaneously due to high pressure/temperature. Pre-ignition happens when fuel ignites before the spark plug fires.

Both can cause: Engine damage and power loss

Environmental Effects

Higher altitude, temperature, and humidity can affect octane requirements. Hot, dry conditions at high altitude may require higher octane fuel.

Rule: Hot + High = Higher octane needed

Engine Modifications

Forced induction, advanced timing, and high compression all increase octane requirements. Always use the highest octane fuel your engine needs.

Guideline: Better safe than sorry

Fuel Selection Tips

Listen for Detonation

Listen for pinging or knocking sounds under load. This indicates detonation and means you need higher octane fuel.

Monitor Temperatures

High engine temperatures can cause detonation. Ensure proper cooling and consider higher octane in hot conditions.

Performance vs Economy

Higher octane fuel doesn't necessarily mean more power. Use the minimum octane your engine requires for best economy.

Engine Modifications

After engine modifications, always verify fuel requirements. Increased compression or boost pressure requires higher octane.