stunthanger.com
Engine basics => Engine set up tips => Topic started by: frank mccune on July 18, 2019, 05:00:14 PM
-
Hi Folks:
I would like to mix to mix some fuel that contains 11% castor oil and 11% synthetic oil. My synthetic oil contains 20% castor oil. How much of each oil do I need percentage wise.
Tia,
Frank
-
This is one of those trick engineering school problems. The correct answer: can't be solved due to lack of sufficient data. One must assume some things in order to get an approximate answer.
Sounds like you have a can of lube which is 80% synthetic and 20% castor. You must first balance the syn/castor mix for equal parts. You have to assume syn and castor are the same specific weight. (they are actually not) Measure out 1.2 oz of your oil mix and add castor until the scale reads 2 oz.
Measure out 1.1 oz of your new oil mix and add combination of methanol and nitro until the scale reads 10 oz. The ratio of nitro to methanol is your choice. (this also assumes methanol and nitro have the same weight/volume; they don't).
(for practical a=mounts, all the above numbers must be multiplied by some constant, depending on how much fuel you want to end up with.)
-
Interesting...I took it to understand the oil is all he was starting with, and was getting bulk castor and methanol.
So, going with my train of thought:
That means 78% is methanol.
Consider each 1% is an ounce:
Also fix your oil in bulk. If the synthetic blend is 1/5 castor, then you need to add castor to the synthetic blend to make 50/50 mix.
So out of 10 ounces of synthetic blend, eight ounces of it is not castor. And two ounces is castor. So add six ounces castor oil to the synthetic blend for 16 ounces of 50/50 mix.
Basically 10:6, or 5:3, or 15:9 for 50/50 oil.
Back to one ounce per percent...
78 ounces methanol
Then premix:
15 ounces synth/castor blend
9 ounces castor
Mix into a container at 100 ounces, and add just enough of your premix to the batch...22 ounces. You'll have 2 ounces of premix left over, but you also have your desired blend.
Shorting each of the oils by one ounce will get you pretty close at 14:8...but you won't have that exact 50/50 oil blend you seek. (78+14+8=100). But at this point you really are within a couple percent.
-
1%= 1 oz ??? Yet another assumption which, although not accurate, tends to simplify everything but does not provide precision results (how much precision do we really need in our fuel mix?)
-
Now if the OP is mid ng two different blends.of fuel, I found that one on Google.
The two fuel mixes are entered into the spreadsheet, and castor oil added is re-calculated to show Methanol Synthetic Castor content.
I can post the link...
-
Just to add more flavor to the brew....
If you purchased an oil that contains 80% by volume of synthetic oil, and 20% by volume of caster oil; and
You want to make a gallon of fuel (128 fl. oz.) with the following percentages by volume: 10% nitro, 22% oil (50/50 synth/castor mix), and 68% methanol; then
In a clean, 1 gallon container add:
17.60 fl. oz. of your magical mystery oil
10.56 fl. oz. of caster oil
12.80 fl. oz. of nitromethane
87.04 fl. oz. of methanol
If you want to change any of these assumptions, let me know and I will run the numbers again.
Dave
Note--fluid ounces are a measure of volume, not weight. Keep everything in volume units and the percentages will make sense for quoted ratios by modelers. If you get into weights, then the math still works, but you will not recognize the numbers. Since you asked for 22% oil, I assumed you meant by volume, because that is a standard ratio. If you want to better understand the changes to the ratios (and the densities of constituents) then go look for the previous fuel thread where I summarized all this.
-
11% / 80% = 13.75% => You need to add 13.75% of your synthetic oil.
11% + 11% - 13.75% = 8.25% => Add 8.25% more of castor oil.
-
Measure out 1.2 oz of your oil mix and add castor until the scale reads 2 oz.
You need to start with 1.25 oz of the oil mix in order to get 1 oz of synthetic oil, as 1.25 x 80% = 1
-
Just mix 6 parts of castor with 10 parts of your synth blend. Then mix whatever % you want with the rest. L
-
Frank,
Attached is a Fuel Mix spreadsheet you can use for any blend you want. Only input into the BLACK cells as the ones in Blue are formula cells.
Best, DennisT
-
Hello:
A big thanks to all of those who replied!
Walter, you are correct! I purchased the incorrect Klotz oil. I am impressed with your detective work. It was very well done.
Again thanks,
Frank McCune