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The removal of tetraethyl lead (TEL) from U.S. automotive gasoline has caused concern within the general aviation (GA) community because of possible legislated environmental or supply restrictions on TEL, an essential ingredient in existing high octane aviation gasolines (avgas). At the same time, the GA industry which was besieged by numerous product liability suits in the past has seen a resurgence since the passage of the GA Revitalization Act in 1994. Because aircraft typically remain in service for many years, the survival of the industry may well depend on the availability of a high octane unleaded gasoline that provides a safe level of power and antiknock performance to the existing fleet. This paper describes the tools and techniques used by one team to develop fuels that provide the required antiknock quality while meeting most of the other criteria of the existing specification for high octane avgas: ASTM D 910, Standard Specification for Aviation Gasolines.

The relationship between the physical and chemical properties and performance of gasolines and diesel fuel are discussed based on work reported in the literature. For gasolines, emphasis is placed on the effects of oxygenates when used as gasoline blending components. With the phase-out of leaded gasoline, and the eventual return of short gasoline supply, the use of oxygenated blending agents will increase in order to meet the octane demands for unleaded gasolines. Octane and volatility are the two most important quality aspects of gasolines. Oxygenates, particularly methanol and ethanol, have definite effects on these properties. The correlation between gasoline composition and its effect on other areas, e.g., emissions, water tolerance and elastomers, are also shown. For diesel fuel, emphasis is placed on the API Gravity, cetane, cloud and pour point, and stability.

The relationship between the physical and chemical properties and performance of gasolines and diesel fuel are discussed. For gasolines, emphasis is placed on the effects of oxygenates when used as gasoline blending components. With the phase-out of leaded gasoline, the use of oxygenated blending agents is increasing in order to meet the octane demands for unleaded gasolines. Octane and volatility are the two most important quality aspects of gasolines. Oxygenates, particularly methanol and ethanol, have definite effects on these properties. The correlation between gasoline composition and its effect on other areas, e.g., emissions, water tolerance and elastomers, are also shown.