https://militaryhistorynow.com/2024...-super-fuels-powered-the-allied-air-war/sample quote
Doolittle lobbied his friends in the U.S. Army Air Corps to convince the service to make 100-octane fuel the standard for both the Army and the Navy. In 1938, the Army Air Corps and Navy agreed to standardize on 100-octane fuel.
Suddenly there was a market, but Shell and other oil companies still had to produce at a cost the U.S. military could afford. Until they adopted a process created by a French émigré, Eugene Houdry, refining crude into 100-octane was time-consuming and expensive.
Houdry came to the U.S. in 1931 after experimenting with processes that converted coal to gasoline. Working with Sun Oil, he developed a new method to economically “crack” crude oil and generate 100 octane gasoline. Then, with the addition of additives like tetraethyl lead, the octane rating zoomed to 100/130.
By the spring of 1940, U.S. refineries were producing enough 100/130 to export to Britain, whose refineries couldn’t make the newer fuel. The modifications to the Merlin engine to take advantage of the higher-octane fuel were known to Rolls-Royce and were incorporated into newer engines.
The difference between 81/87 and 100/130 in a Hurricane II or Spitfire II was transformative.
Depending on the altitude, airspeeds jumped by 30 to 40 knots, and rates of climb increased by 500 to 1,000 feet per minute. Luftwaffe fighter pilots escorting bombers over Great Britain during the Battle of Britain suddenly found that their performance advantage had evaporated.
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By D-Day, 100/150 44-1 fuel had become the standard; the performance increases outweighed the wear and tear on aircraft and accompanying maintenance headaches. The biggest of these was a decrease in spark plug life. After only 12 to 15 flight hours, or two seven-hour or three, four-hour missions, the plugs had to be changed.
Rough running at low power settings (lean mixture, low rpm, low manifold pressure) caused by fouling plugs was also a problem. The solution was to run the engines at a “high” power setting for two to three minutes when the engine began to run rough. High power being defined as between 30 and 40 inches of manifold pressure and maximum rpm.
A third problem was that 100/150 ate up synthetic rubber parts into which it came in contact. This required careful monitoring and more frequent replacement of these parts. In an interesting note, the AAF noted that the high toxicity of 100/150 required careful handling.
Deposits on the valve seats, cylinder bores, and rings in the Allison engines was yet another problem.
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