I dispute taht fact taht everyone kn ew about Europen fuels becuase opur wearly planes arrived there jetted for American fuel and sufffered operational issues.
We may be getting confused as to which year we are talking about. In 1940 EVERYBODY who mattered knew the fuel was different. One reason the Americans were specifying low aromatic fuel was that the high aromatic fuel tended to dissolve (eat) certain rubber compounds used in American fuel systems. American 100 octane fuel had NO rich mixture response other than what you get going to a rich mixture. American 100 octane fuel was 100 octane running lean and just about 100 octane running rich
ONCE the got around to measuring rich response. Now in 1940/early 1941 there were darn few American planes actually being used by the British and certainly no American planes being flown by the Americans in Europe or any other combat theater. British 1940 100 octane fuel with it's 20% (or more) aromatic content, was good for about 115-125 octane ( or performance number) depending on batch. Since in 1939/40 the fuel specification did NOT list a rich mixture number limit as such. As more testing and research went on specifications were written to include the rich mixture response as a measured number and specifications for 100/120, 100/125 (fuel specification AN-F27), and 100/130(fuel specification AN-F28) were quickly written and very quickly superseded each other. the 100/125 may have been an american specification as a number of Allison engines were rated on it. The 100/130 was standardized between the US and the British in fairly short order though. The Americans changing their fuel systems to accommodate the high aromatic fuel.
There are a number of things that go into fuel and fuel specifications. Fuel has to have a certain number of BTUs per gallon, certain gum and/or residue limits, it is held to certain vapor pressure and evaporation limits not to mention lead limits. There are something over 400 compounds that can be used in aviation gasoline. and different compounds or mixtures of common compounds react differently to the addition of certain other compounds, like lead. Some blends give a very significant increase in octane numbers with addition of small amounts of lead, other blends show only a modest increase with the addition of the same amount of lead. Some blends show a bigger change between lean and rich mixture ratings with the same amount of lead than other blends do.
In 1940 The written specifications for American and British fuel spelled out the difference in aromatic compound content. By the middle of the war the Waukesha company had delivered hundreds of single cylinder test engines to oil refineries, research labs and government purchasing agencies to help make sure every body was on the same page as far as testing fuel goes.
Now as more and more high octane fuel was wanted and as supplies of certain compounds changed and as different refining processes were brought online (cat cracked fuel behaves differently than straight run gasoline and straight run can vary depending on the oil field it comes from) the blends or allowable blends were changed to meet the production quotas. It was one of these changes that prompted the development of the Center venturi intake pipe on the Allison. By now it is 1943 and some of the "allowable" blends of 100/130 fuel are not the same as the older 100/125 and 100/130 fuel. Allison knew this and was working on the new manifold before the problem ever cropped up in Europe. It is just that events overlapped. There may have been a few batches of fuel that were less than perfect also.
The "story" that American fuel was "good" and European (British, what other European nation was supplying fuel for American aircraft in 1943/44)fuel was "bad" needs a rethink. There is little point in "standardizing" fuel between allies if major differences are knowingly allowed.
Last, taking the P-38 to "warmer eather" would have no effect. Once above 20,000 feet or so, whether youa re in the tropic or over Great Britian or germany, youa re in about teh same temperatures. The reason the P-38's suffered fewer issue in the pacific was they were running American gasoline and, once they were cured of other issues, they operated just fine. All that happened early in Pacific deployment is that the issues with European gasoline use were never there to stat with, ergo no detonation from excessive aromatics versus the jetting.
You have to go a lot higher than 20,000ft and most air temperature charts do show a difference. There were charts for standard days and "hot days" let alone tropics. Differences could extend well into the 30,000ft range.
P-38s also suffered problems in other theaters, just not as bad or as widely publicized.
There were a number of contributing factors, mis-rigged turbo/throttle controls, poor piloting technique, the temperature ( and the planes operating in the tropics seldom spent as much time (several hours at a time) at high altitudes as the European planes), and the change in KNOWN fuel blend. Throw in a couple of 'poor' batches of fuel with a mixture of the 4 listed "factors" and you get the problem coming up a lot. Take away 2 or 3 of those factors, or even ONE, and the scope of the problem changes.
Late war US fuel use the same high % of aromatics as the British did, especially when you get to things like 100/150 or the post war 115/145 fuel (AN-F-33)