I thought this blog post would give an insight to the method used for blending racing fuels in the 1940/50’s. The guidelines for fuel blending come from Jimmie Simpson’s notebook (Jimmie Simpson Blog post)used when he was competitions manager of Shell-Mex and B.P. Ltd.
The blending process:
1)
Inspect the 50-gln. Barrels to see that they are
thoroughly clean and unlined – for this inspection a special inspection lamp is
being sent to the depot.
2)
Clean all equipment that is to be used
(measures, funnels etc) by washing with spirit or benzol (dependent on the type
of fuel being blended).
3)
Calculate the quantity of components required
and stack the cans in separate piles near the blending barrels.
4)
Take a sample of each ingredient from the bottom
of the packages by using the valinche and test the specific gravity (see table
for specific gravities)
5)
Calculate the specific gravity of the resultant
mixture arithmetically (see example)
6)
Calculate the best means of having complete
blends in each of the barrels at your disposal (i.e. halve the components and place
half in barrel 1 and half in barrel 2, when blending operations commence).
7)
Start blending by filling into the barrels the
ingredients having the lowest specific gravity. Then add alcohol and benzol
alternatively. These latter components, having a greater gravity will fall to
the bottom of the barrels, whilst the lighter spirit will tend to rise, and in
so will mix to a certain extent with the other ingredients. As cans are
emptied, stack on one side and leave until the blend is completed, mixed and
sampled. Any error in the resultant specific gravity can then be checked
against the actual components used. When figures are agreed, remove the empty
packages and commence canning of the blend.
8)
Use either a 2-gln. or a 5-gln. measure each
time to ensure that the correct quantity has been used. (Do not pour
straight from the cans, as it is impossible to say whether they contain the
exact tow gallons.)
9)
In adding the dye, care should be taken that it
is added a little bit at a time, during the actual blending, to ensure complete
mixing.
10)
If it is necessary to add Castor Oil to the
mixture, then the oil should be mixed thoroughly with part of the Methanol
and/or Ethanol, and added to the blend; vigorous stirring should accompany this
process. A milky, frothy mixture will result when the Castor Oil is added to
the mixture, but this will disappear when the mixture is assed to the bulk
blend. The resultant fuel, however, will not have the same crystal clear
appearance as a fuel with no oil addition.
11)
If, on the other hand, it is necessary to add a
mineral oil to the mixture, e.g. Triple Shell (Heavy), the same process should
be carried out, but the oil should be mixed with the benzol or petrol
(preferably the benzol) and not to the alcohol.
12)
When the blend is finished, replace the bung and
roll the barrels for a short while to ensure that the components are thoroughly
mixed – alternatively stir the mixture with a clean, un-painted wooden or metal
dip-stick during blending, which will reduce the rolling period required to a
minimum.
13)
Replace the barrel on the stollard and by using
the valinche take a sample from the bottom of the barrel and check for
appearance and take the specific gravity. This latter should be the same as was
calculated in (5) by calculation, but if there is a discrepancy check through
all the process and make sure that the correct quantities have been added: also
check your calculations.
14)
When the gravity is agreed, canning operations
may be started (each can should be carefully examined beforehand to see that it
is perfectly clean).
15)
When all filling is finished, carefully clean
and dry the hydrometers and keep an exact record of the blend made in a special
book, together with dates, quantities of ingredients, etc.
16)
If at any time it is necessary to blend a
special mixture for anybody, full details are to be kept, together with the
person’s name and performance of the fuel in the engine concerned.
Specific Gravities @
60°F
Methanol .796
Ethanol/Benzol .820/.825
Ethanol/224 .783
Ethanol/Shell .783
DTD 224 .736
Shell .736
Benzol .860/.870
T.T. Benzol .873
Swan .685
Acetone .796
Water 1.000
Shell Castor Oil G .950
Specific Gravity
Correction factors per every 1°F
are:-
Petroleum Spirit of Specific gravity .675/.714 0.0005
do. do. .715/.750 0.00045
do. do. .751/.800 0.0004
Alcohol .780/.820 .0005
Benzol .860/.880 .0006
Examples:-
Spirit of specific gravity .730 @60°F – to calculate its specific
gravity @ 50°F
:-
Temperature difference = 60-50 = 10°F
Correction factor - .00045 per 1°F
0.000045 x 10 for 10°F = 0.0045
As temperature is lower than 60°F, add factor to
specific gravity @ 60°F: .730 + .0045
= .7345 – Specific Gravity at 50°F
Spirit of specific gravity .730 @60°F – to calculate its specific
gravity @ 70°F
:-
Temperature difference = 70-60 = 10°F
Correction factor - .00045 per 1°F
0.000045 x 10 for 10°F = 0.0045
As temperature is lower than 60°F, subtract factor to
specific gravity @ 60°F: .730 - .0045
= .7255 – Specific Gravity at 70°F
Method of calculating
specific gravities:-
Note: For the
purposes of these examples gravities are quoted at 60°F. It should be remembered
that should the temperature be below 60°F the component will have a higher
specific grvity and if above 60°F, the component will have a lower
specific gravity.
811
Specification: % S.G.
Methanol 80x .796 63680
Benzol 10x .862 8620
Acetone 10x .796 7360
79960
Specific gravity of resultant mixture is .7966 by
calculation
D.4.
Specification: % S.G.
Ethanol 70x .820 57400
Benzol 20x .860 17200
Shell 10x .736 7360
81960
Specific gravity of resultant mixture is .8196 by
calculation
BP Racing Ethyl
Specification: % S.G.
Methanol 97x .796 77212
Acetone 3x .796 2388
79600
Specific gravity of resultant mixture is .796 by calculation
Dye addition = ½ pint
Master Dye Solution per 100 gallons
=284 ccs. Master Dye Solution per 100 gallons.
=10 fluid ozs. Master Dye solution per 100 gallons.
Dye addition per
gallon = 2.84 ccs. Master Dye Solution per 1 gallon – say 3ccs Master Dye
Solution per 1 gallon.
This is great stuff! Thanks for sharing the info with us. Did you get Simpon's black book at an auction?
ReplyDeleteYes that is correct. I have a few other posts planned around it - fuel blends for specific famous cars, sponsored drivers/riders etc.
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