Aviation gasoline specifications: The octane rating assigned to aviation gasoline can reach what approximate level under performance number scales?

Introduction / Context:
Aviation piston engines demand high knock resistance due to high manifold pressures, supercharging, and severe duty cycles. Aviation gasoline is therefore formulated with very high octane quality, often beyond the conventional motor gasoline scale, and uses performance numbers exceeding 100.

Given Data / Assumptions:

• Octane scales include RON and MON for automotive fuels; aviation uses lean and rich mixture octane ratings with performance numbers.
• High-performance aviation gasolines historically use tetraethyl lead and optimized blending components.
• Engines may operate rich to manage cylinder head temperatures and detonation margins.

Concept / Approach:

Performance numbers extend the scale above 100 by comparing knock-limited power output of the test fuel to that of isooctane with supercharging. As a result, aviation grades such as 100/130 indicate knock ratings beyond 100 under certain mixture conditions.

Step-by-Step Solution:

Verification / Alternative check:

Fuel grade designations like 100LL confirm octane equivalence above 100 for aviation use, matching detonation resistance requirements.

Why Other Options Are Wrong:

Values of 79, 87, and 97 correspond to automotive fuel ranges and are insufficient for many high-output aircraft piston engines.

Common Pitfalls:

Confusing automotive RON with aviation performance numbers; forgetting that the aviation scale extends beyond the isooctane cap.

Final Answer:

>100