British Lead Additive Production
I suspect that the lower rating was the published pre-war figure and one would not advertise a massive engine improvement subsequently to one’s enemies.
As others have written the Battle of Britain was nearly completely won with US lead additive but the following may be of interest.
The following are my notes made about the Associated Octel plant Northwich and are based on commemorative history produced by the company “Making the magic bullet: a history of Northwich Works 1939-1986”
“During the 1920’s General Motors and Standard Oil (Esso) jointly developed anti-knock petrol additives through the Ethyl Gas Corporation. These compounds fractionally delay ignition of petrol/air mixtures in car and aircraft engines, allowing the engine to compress the mixture more, making the power levels higher. Britain first imported these compounds in 1928 and then throughout the 1930’s but with war looming decided that the RAF needed higher compression engines. From 1936 the Air Ministry worked with the joint partnership of the Associated Ethyl Company (importers) and ICI (manufacturers ) and eventually placed orders to build the Northwich site.
Two alkyl lead compounds, tetraethyl lead (TEL) or tetramethyl lead (TML), are used as antiknock gasoline additives. Only TEL was produced during the war. Lead alkyl is produced in autoclaves by the reaction of sodium/lead alloy with an excess of either ethyl (for TEL) or methyl (for TML) chloride in the presence of an acetone catalyst.
The first batch of TEL was produced in September 1940. Until then, the RAF fuel had been treated with imported TEL. The workforce was all drawn from ICI Winnington and Lostock, and was largely self-taught in controlling this new process.”
The 1930’s imports allowed Rolls Royce to deliver the power required for the Schneider Trophy power plants, and design engines with the required metallurgy to handle that power. The Merlin therefore had the TEL technology built in from the start.”
I cannot find my copy of Stephen Bungay’s book on the Battle of Britain but I think he may have some German reaction to this British advance. If anyone has any knowledge of the German pilot reactions to meeting Spitfires and Hurricanes suddenly performing better after the increase in octane rating from 87 to 100 it would be interesting to learn of them.
McKinstry Spitfire Portrait of a Legend p356 quotes F/L Ponsford as flying a Spitfire XIV (Griffon) with 150 octane fuel and IIRC the Sea Fury Centaurus is 130 octane rated, so development continued to the war’s end and beyond, with interesting other options including water and methanol injection to increase power output.
WZ862
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