1. #1
    One interesting historical issue involving octane rating took place during (Click link for more info and facts about WWII) WWII. (A republic in central Europe; split into East German and West Germany after World War II and reunited in 1990) Germany received nearly all her oil from (A Balkan republic in southeastern Europe) Romania, and set up huge distilling plants in Germany to produce petrol from coal. In the (North American republic containing 50 states - 48 conterminous states in North America plus Alaska in northwest North America and the Hawaiian Islands in the Pacific Ocean; achieved independence in 1776) US the oil was not "as good" and the oil industry instead had to invest heavily in various expensive boosting systems. This turned out to be a huge blessing in disguise. US industry was soon delivering fuels of ever-increasing octane ratings by adding more of the boosting agents, with cost no longer a factor during wartime. By war's end American aviation fuel was commonly 130 to 150 octane, which could easily be put to use in existing engines to deliver much more power by increasing the compression delivered by the (Compressor that forces increased oxygen into the cylinders of an internal-combustion engine) superchargers. The Germans, relying entirely on "good" petrol, had no such industry, and instead had to rely on ever-larger engines to deliver more power.

    However, someone pointed out that: German aviation engines were of the direct fuel injection type and could use emergency methanol-water and nitrous-oxide injection, which gave 50% more engine power for 5 minutes of dogfight. This could be done only five times and then the aero engine went to the scrapyard (or after 40 hours run-time, whichever came first). Most German aero engines used 87 octane fuel (called B4), some high-powered engines used 100 octane (C2/C3)fuel.

    Another pointed out in reply that: This historical "issue" is based on a very common misapprehension about wartime fuel octane numbers. There are two octane numbers for each fuel, one for lean mix and one for rich mix, rich being always greater. So, for example, a common British aviation fuel of the later part of the war was 100/125. The misapprehension that German fuels have a lower octane number (and thus a poorer quality) arises because the Germans quoted the lean mix octane number for their fuels while the Allies quoted the rich mix number for their fuels. Standard German high-grade aviation fuel used in the later part of the war (given the designation C3) had lean/rich octane numbers of 100/130. The Germans would list this as a 100 octane fuel while the Allies would list it as 130 octane.

    After the war the US Navy sent a Technical Mission to Germany to interview German petrochemists and examine German fuel quality, their report entitled "Technical Report 145-45 Manufacture of Aviation Gasoline in Germany" chemically analysed the different fuels and concluded "Toward the end of the war the quality of fuel being used by the German fighter planes was quite similar to that being used by the Allies".

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  2. #2
    By March of '45 the AAF had switched completely (having started in February) from 100/130 to 100/150 (called Pep). A problem popped up in the form of corroded valve seats and was dealt with by increasing maintainance. The Brits were, at the end of the war, experimenting with 130/170 . . .
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  3. #3
    Art-J's Avatar Senior Member
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    Nov 2003
    Interesting info, I've always wondered what these mixed 100/130 or 100/150 designations meant. Now I know.
    BTW, after some web searching and reading, do these numbers are somehow related (the same?) to MON and RON rating numbers described here?
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  4. #4
    My initial reason for posting this was to show that US planes (mainly the P-47) did in fact use 150 octane feul on a regular basis, to stop any debate that may occur on such matters. The rest of the stuff was just a bonus. And LW fans alike can find some stuff that can help future debates for them as well.
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  5. #5
    Very interesting. I always wanted to know where Germany, the States and Romania are.
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  6. #6
    Originally posted by neural_dream:
    Very interesting. I always wanted to know where Germany, the States and Romania are.
    I dont understand that response
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  7. #7
    alert_1's Avatar Senior Member
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    Apr 2005
    Would be intersting what kind of performance these "bigger and bigger" german engines were capable if they were fed (a boosted accordingly) with 150octan fuel..
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  8. #8
    During the later half of the 1930's, Jimmy Doolittle had a hand in trying to make the standard aviation fuel in the United States as 100 octane. There were many different octane aviation fuels out there at that time whick made it hard on the aviation industry to standardize. Since the peacetime Army Air Corps had too many majors, Doolittle slipped off from active duty and became a vice president at an oil comapny (Shell I believe). Previously he worked at NACA and did air racing on temporary leave from the military. Also during this period he was in the first class to recieve a PhD in Aeronautical Engineering from MIT. This arrangement allowed other officers to be retained on duty. At Shell he pushed forward and lobbied the US government to make the 100 octane fuel a standard for ciivl and military aviation.
    This allowed for quicker mobilization later on as you only had one fuel type to work with. Later the engineers in an effort to boast more power out of the aircraft higher octane formulations were being utilized as the 100/130 and 100/150 mixtures. Other countries didn't standardize their fuel needs so you had situations were multiple storage facilities and distribution equipment had to be used to kept on hand to service the various aircraft.
    I am not too sure on the German aircraft, but I believe they used either 75 or 87 octane grades of av gas.
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  9. #9
    Originally posted by alert_1:
    Would be intersting what kind of performance these "bigger and bigger" german engines were capable if they were fed (a boosted accordingly) with 150octan fuel..
    I don't think there would have been a difference, just the engines requiring a different setup.

    What I understood from the discussion was the the germans used less quality base "fuel" (from coal) and increased the quality to 100 octan by addons (I think the common method today to make cheap high quality fuel). The US used simple refining to get 100/150 fuel. This means you throw away most of the raw oil (as they had more than enough). By using addons you can make "high octane" fuel out of less quality parts of the oil, making more/cheaper.

    There would have been a difference
    1. if the germans had lots of 100/150 "raw" fuel
    2. if it is possible to increase the octane rate of 100/150 by addons
    3. if this would produce higher engine power
    I'm not sure about all this "if", we still use 100 octane fuel today.

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  10. #10
    48 conterminous states in North America
    LOL, you had me scrambling for my dictionary on that one! And, waddayaknow, there is such a word! Means having common borders.

    The term in the U.S. is contiguous United States. Hawaii and Alaska are the non-contiguous United States

    Your point about the Germans using synthetic oil and Romanian oil is every but as important strategically as octane levels.

    Germany did not have an adequate oil supply to carry on a lengthy war.

    Germany invaded the Crimea to deprive Russia of air bases from which to bomb Romanian oil fields.

    And Germany was in the process of attacking the Caucasus in order to seize the Russian oil fields there.

    Hitler's obsession with Stalingrad ended the German advance in the Caucasus just short of the oil fields and the units were sent to Stalingrad, an enormous mistake.

    For both the Germans and the Japanese, World War II was about oil.

    Things haven't changed much, have they?

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