A Historical Analysis of the Co-evolution of Gasoline Octane Number and Spark-Ignition Engines

Abstract

In this work, the authors reviewed engine, vehicle, and fuel data since 1925 to examine the historical and recent coupling of compression ratio and fuel antiknock properties (i.e., octane number) in the U.S. light-duty vehicle market. The analysis identified historical time frames and trends and illustrated how three factors-consumer preferences, technical capabilities, and regulatory legislation-affect personal mobility. Data showed that over many decades these three factors have a complex and time-sensitive interplay. Long-term trends in the data were identified where interaction and evolution between all three factors were observed. Specifically, transportation efficiency per unit power (gal/ton-mi/hp) was found to be a good metric to integrate technical, societal, and regulatory effects into the evolutional pathway of personal mobility. From this framework, discussions of future evolutionary changes to personal mobility are also presented, with a focus centered on how increasing fuel octane number can help to enable sustained improvement in transportation efficiency per unit power.

Combustion-Based Transportation in a Carbon-Constrained World—A Review

“…One inhibitor in improving the fuel efficiency of these engines was their low compression ratio, which was limited by engine knock (Seyferth 2003). Fuels at that time had lower octane numbers because of limited advancement in refinery processes (Splitter et al 2016) such as catalytic reforming, cracking, etc. Amid attempts on engine and fuel improvement in the 1920s, a young engineer Thomas Midgley and his associates came up with the suggestion of blending small quantities of Tetra Ethyl Lead (TEL) to the gasoline to increase its knock resistance and hence allowing engines to deliver higher power and better efficiency in the process.…”

“…Amid attempts on engine and fuel improvement in the 1920s, a young engineer Thomas Midgley and his associates came up with the suggestion of blending small quantities of Tetra Ethyl Lead (TEL) to the gasoline to increase its knock resistance and hence allowing engines to deliver higher power and better efficiency in the process. However, due to health and environmental impacts of TEL, it was phased out in the 1970s around major parts of the world, thereby affecting the automotive efficiency adversely (Splitter et al 2016). Soon after, automotive manufacturers started using electronic fuel injection system and engine management software, which revived engines' performance to TEL levels.…”

Combustion characteristics of various fuels during research octane number testing on an instrumented CFR F1/F2 engine

“…Initially the MON condition, with higher mixture temperature entering the engine and higher engine speed, was designed to be more representative of "higher severity" engine operation when compared to early vehicle road octane number testing. However, with the current trend of engine down-sizing and boosting, the cylinder pressures and temperatures common of modern turbocharged gasoline direct injection (GDI) engines are more similar to, if not beyond, the relatively lower temperature and higher pressure RON conditions [3,4]. For this reason, and because of its more widely accepted use, the current study will focus on the cylinder combustion and engine operation conditions of the RON test method (ASTM D2699).…”

Effect of Different Fluids on Injection Strategies to Suppress Pre-Ignition

“…A few trends are prominent: (1) more than 50% vehicles in the U.S. have turbocharged engines (2) Vehicles with 6 or more gears (including CVTs) account for around 50% of the total vehicles. (3) Gasoline Direct Injection vehicles make up 60% of the total vehicles [19,20]. Together, (1) and (2) adoption trends have led to a larger fraction of engine operating at low speed and high load area.…”