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Home Brew - 4/6/2007 12:19:15 PM   
voodoodb



Posts: 223
Joined: 6/9/2002
From: Flora, MS, USA
Status: offline 		I have noticed that I am getting alot more oil from my hame brew fuel than with store bought fuel coming from the exhaust. I blended my fuel by weight, to 2 decimal points, using the Specific gravity of the 3 components, with 10% Nitro, 19% castor oil and the rest methanol.

Since castor oil doesn't burn off like Synthetic will, is it OK to use a lower oil content when using straight castor?

Thanks

Doug
       Post #: 1

RE: Home Brew - 4/6/2007 3:15:25 PM   
Fuel Dinosaur


 

Posts: 85
Joined: 6/25/2002
From: Warrenton, GA, USA
Status: offline
quote:

ORIGINAL: voodoodb

I have noticed that I am getting alot more oil from my hame brew fuel than with store bought fuel coming from the exhaust. I blended my fuel by weight, to 2 decimal points, using the Specific gravity of the 3 components, with 10% Nitro, 19% castor oil and the rest methanol.

Since castor oil doesn't burn off like Synthetic will, is it OK to use a lower oil content when using straight castor?

Thanks

Doug

A lot of oil is fine, however I would suggest you consider using simple volumes for measurement and not specific gravity. Nitromethane is very dense and adding 10% by specific gravity leaves you short of nitromethane volume, that is you do not have 10% actual volume in your fuel, it is quite a bit less, based on the specific gravity of nitromethane. With many engines, this lower nitro is okay. If oils are not very dense, and they are certainly nowhere near that of nitromethane, you might take a look at the actual VOLUMES of each components you are using. One of the very simplest ways for folks to do homebrew on a small to gallon size lot of fuel is to either use 1000 ml Pyrex measuring cups (a little over a quart) or, better yet, a 4000 ml (glass or Nalgene) graduate cylinder. Percents are EASY using metric. For example, if you wanted 10% nitro in 4000 ml of fuel, then add 400 ml (.10 x 4000 ml.)to that 4000 ml cylinder. If you wanted 18% final oil, then add .18 x 4000 ml of oil and so forth. Some fuel manufacturers are using weight instead of volume and their 15% nitro has a LOT less than that in terms of simple total volume of the fuel. In my view, this is very deceptive and confusing to modelers to do this.

(in reply to voodoodb)
       Post #: 2

RE: Home Brew - 4/6/2007 4:29:19 PM   
JCINTEXAS


 

Posts: 407
Joined: 3/23/2007
From: Smithville, TX, USA
Status: offline 		Years ago I mixed my own glow fuel in increments of 100 ounces to keep it simple.
Example: 20 ounces oil - 5 ounces nitro - 75 ounces methanol
Double or triple the recipe for larger batches.
Does anyone know where I can purchase small quantities of oil, methanol, and nitro.
Or even just the oil and methanol?
5 gallons purchase or less.
Thanks
JC in Texas

(in reply to Fuel Dinosaur)
       Post #: 3

RE: Home Brew - 4/8/2007 12:48:55 AM   
voodoodb



Posts: 223
Joined: 6/9/2002
From: Flora, MS, USA
Status: offline 		Thanks Guys, also Someone told me that the methanol used in paint manufacturing is a lower grade than that used in Fuel. I checked with our QC dept. and chemist. They said our min standard is 99.5% pure. Is this not good enough to make good fuel?

Thanks
Doug

(in reply to JCINTEXAS)
       Post #: 4

RE: Home Brew - 4/8/2007 7:25:48 AM   
downunder



Posts: 3198
Joined: 10/10/2002
From: Adelaide, AUSTRALIA
Status: offline
quote:

ORIGINAL: voodoodb
They said our min standard is 99.5% pure.

That should be more than good enough because I believe the usual purity for fuel is about 99.8% and even if that extra .3% impurity is water then no problems. I've added up to 3% water to fuel and didn't notice any difference in starting or running characteristics. But with 4% water all the oil fell to the bottom of the tank and it was impossible to start the engine (it seems they won't run on pure oil ).

JCINTEXAS has the right idea for mixing fuel because he's using a metric system where you can work out the volumes needed in your head, no calculators needed .

(in reply to voodoodb)
       Post #: 5

RE: Home Brew - 4/8/2007 3:41:29 PM   
blw



Posts: 4569
Joined: 3/15/2004
From: Auburn, AL, USA
Status: offline 		It's not that difficult to work out in your head using other increments, like gallons, etc. Keeps the brain from becoming lazy too.

_____________________________

The ultimate responsibility of pilots is to fulfill the dreams of the countless millions who can only stare skyward...and wish.

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       Post #: 6

RE: Home Brew - 4/8/2007 4:55:21 PM   
Jim Thomerson



Posts: 2825
Joined: 10/9/2002
From: Austin, TX, USA
Status: offline 		Easiest thing to do is put measured quanties in your fuel mixing jug and make marks on the side. From then on just fill up to the marks in sequence. No clean up involved.

(in reply to blw)
       Post #: 7

RE: Home Brew - 4/8/2007 5:10:37 PM   
downunder



Posts: 3198
Joined: 10/10/2002
From: Adelaide, AUSTRALIA
Status: offline
quote:

ORIGINAL: blw
It's not that difficult to work out in your head using other increments, like gallons, etc. Keeps the brain from becoming lazy too.

That's true if you were mixing in 100 gallon lots but if I was mixing up just a gallon then I'm blowed if I could work out in my head what 18% of 128 ounces is to add some oil .

(in reply to blw)
       Post #: 8

RE: Home Brew - 4/8/2007 7:40:35 PM   
Jim Thomerson



Posts: 2825
Joined: 10/9/2002
From: Austin, TX, USA
Status: offline 		Here is how my father (5th grade education) would have figured it. .2 x 128 = 25.6. Then .02 x 128 = 2.56. 25.6 - 2.56 = 23.04 = 18% of 128. I don't have a calculator or spreadsheet at hand so I'm not sure I did it right.

(in reply to downunder)
       Post #: 9

RE: Home Brew - 4/9/2007 4:02:35 AM   
blw



Posts: 4569
Joined: 3/15/2004
From: Auburn, AL, USA
Status: offline 		Easy enough. Take 10% of 128=12.8. 10 of 12.8=1.28x2. Add those quickly and subtract from 128 in your head. Done in about 5 seconds or so......

_____________________________

The ultimate responsibility of pilots is to fulfill the dreams of the countless millions who can only stare skyward...and wish.

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       Post #: 10

RE: Home Brew - 4/9/2007 11:14:38 PM   
Jim Thomerson



Posts: 2825
Joined: 10/9/2002
From: Austin, TX, USA
Status: offline 		BLW, something got lost in translation there, I think . No comprendo.

(in reply to blw)
       Post #: 11

RE: Home Brew - 4/10/2007 1:45:01 AM   
blw



Posts: 4569
Joined: 3/15/2004
From: Auburn, AL, USA
Status: offline 		Misread to be wanting the reverse; 82% of 128. Get 10% of 128. Get 10% of the result and double that (equals 2% of 128). Subtract the 2% answer from the 10% answer (result is 8% of 128). Add those together and you have 18%. Anyway, this is getting off track with a lot of my help. 8*)

_____________________________

The ultimate responsibility of pilots is to fulfill the dreams of the countless millions who can only stare skyward...and wish.

(in reply to Jim Thomerson)
       Post #: 12

RE: Home Brew - 4/10/2007 4:28:08 PM   
Fuel Dinosaur


 

Posts: 85
Joined: 6/25/2002
From: Warrenton, GA, USA
Status: offline
quote:

ORIGINAL: Jim Thomerson

BLW, something got lost in translation there, I think . No comprendo.


Me neither!!

I do not understand the math people are presenting here for fuel. If you want 18% final oil in a new fuel, you convert the 18% to its decimal equivalent, 0.18 ( some say just .18, same thing) and multiply it by the amount of fuel you are making, like 4000 ml, so you would take .18 x 4000 ml to get the ml of oil to add to your final 4000 ml. Of course ALL the decimal equivalents together must equal 1.0 or 100% of the fuel. For 15% nitro it would be, in this example, .15 x 4000 ml or 600 ml of nitro. All the rest of the volume would be methanol if you are adding just the one oil. What I suspect is that a lot of folks forgot that half of a pie is also 0.50 or .50 of the total pie, and the total pie is 1.0 Mixing different fuels is a little harder, or when you add, say castor oil to a fuel and change not only the oil content, but also the volume at the same time. Some of these roundabout explanations are harder to understand than just making it up using simple volumes and converting percents to their corresponding decimal. Like 1/3 of something is .33333..... or 3/4 of something is .75 In my opinion, many folks just do not remember how to do this. Hope this makes some sense to you. Terry Joe Sprinkle (The old fuel mixing dinosaur)

(in reply to Jim Thomerson)
       Post #: 13

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