Jump to content

Help verifying a statement about fuel ratings during WWII

Recommended Posts

In the link below I read the excerpt which I posted. Can anyone verify this claim?
A common misconception exists concerning wartime fuel octane numbers. There are two octane numbers for each fuel, one for lean mix and one for rich mix, rich being greater. The misunderstanding that German fuels had a lower octane number (and thus a poorer quality) arose because the Germans quoted the lean mix octane number for their fuels while the Allies quoted the rich mix number. Standard German high-grade 'C-3' aviation fuel used in the later part of the war had lean/rich octane numbers of 100/130. The Germans listed this as a 100 octane fuel, the Allies as 130 octane.
Edited by JG7_X-Man
Link to post
Share on other sites

I'm currently reading this.  I haven't finished it yet, but briefly looking through some of the later war content it would appear that there is some truth to this statement.  The material in the book is quite dense covering many aspects of engine development (the author is an F1 engine designer).  Flipping through some of the later sections that I haven't read yet, I found a part where the author goes into some detail about a German test of captured Allied fuel in August of 1944 "All that could be stated definitively was that the 150 grade Allied fuel was markedly superior to C3 at lean mixtures and about equal at fuel-rich mixtures."  There is some discussion later that German fuel quality really fell off going into 1945 as the Allied Oil campaign continued to crush the refineries.  As I get to that part of the book and read more into it, I'll update my post here.

  • Like 1
Link to post
Share on other sites
  • 3 weeks later...

Some further quotes from the book I linked above:


"Seeber had confirmed what had been suspected for some time - that the octane system could not be used to accurately determine how much power could be extracted from a fuel in a real engine."


"... the crucial point was the difference in performance between iso-octane rich fuels used by the Allied nations (containing paraffins) and high aromatic content German synthetic fuels.

    The synthetic aromatic fuel gave exceptional engine performance, but only at low air temperature and at fuel-rich air mixtures.  Not only that but the variation was for more extreme than that shown by fuels given their performance by iso-octane addition.  The engine designer able to use iso-octane to boost their fuel performance could be sure of good engine performance despite variations in temperature and fuel mixture.  The designer forced to use aromatics could only be sure of good performance under fuel rich conditions and had to allow for a drop in performance as high as 50% if the engine had to run lean, as would be the case in cruising.  The Allied 100 octane fuel performance was based entirely on the addition of iso-octanes produced by the Alkylation of crude oil; a process first commercialized by the Ethyl Corporation in the USA.  Germany had  no such supply and found iso-octanes difficult to produce in high volumes from hydrogenation."


The book is largely in chronological order, and I'm still in the late 30's so I'm sure there will be more interesting nuggets on this topic to come.

  • Upvote 1
Link to post
Share on other sites
  • 2 weeks later...

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
  • Create New...