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General control line discussion => Open Forum => Topic started by: Kevin prier on February 09, 2015, 06:33:01 PM
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I need someone to clear this up for me. when I add extra castor oil I'm not sure how much im adding. This is what I gather with the percentages. I use 15% nitro 20% oil. 128 OZ in a gallon. 20% of 128 oz is 25.6 oz of oil. That works out to a 5:1 ratio. Is there really 25.6 oz of oil in my gallon of fule. I have mixed a lot of two stroke gas in my life and just can't belive this is correct.
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Yup. That's exactly what I get - 25.6 oz of 128 is 20%.
I generally buy the 17% oil blends and add ~2 ounces of castor to get the total mix of 130 ounces up to ~18+ % oil (about 23.8 oz of total oil).
And usually the goo left on the plane after the flight is ~30% castor, 68% synthetic oil and 2% bug parts and grass flakes.
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....20% of 128 oz is 25.6 oz of oil. That works out to a 5:1 ratio.
That's really a 4:1 ratio because 20% of the total fuel (100%) is oil while the remaining 80% is the fuel part of the total. So 80% to 20% is a 4:1 ratio.
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Did any of the two strokes you mixed gas and oil for turn 15,000 all day with ease?
MM
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I need someone to clear this up for me. when I add extra castor oil I'm not sure how much im adding. This is what I gather with the percentages. I use 15% nitro 20% oil. 128 OZ in a gallon. 20% of 128 oz is 25.6 oz of oil. That works out to a 5:1 ratio. Is there really 25.6 oz of oil in my gallon of fule. I have mixed a lot of two stroke gas in my life and just can't belive this is correct.
It's correct. Two big differences are that castor oil and whatever synthetics we use aren't as good as 50:1 two-stroke oil, but those don't go well with alcohol fuels. The other is that the oil acts partially as a coolant, effectively a total-loss lubrication and cooling system. Older engines depend on this to stay alive. Newer engines need less than 20% - I have routinely run 16% straight synthetic with no wear issues on very high-quality AAC engines. Put that in a Fox 35 and it will possibly wear out the piston/liner or even seize in a few minutes from either friction or lack of cooling, or both.
A third, lesser difference is that gasoline itself has some minimal lubricating properties.
Brett
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Here is a spreadsheet that allows you to figure out ratios of oil content, (castor and synthetic), nitro content, and methanol content.
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Here is a link to a website with a calculator for adding oil and or nitro to fuel to get total percentages
http://www.nitrorc.com/default2.asp?Introduction=http://nitrorc.com/fuelws
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The higher the nitro % the more fuel going through the engine which means more oil so 20% oil is plenty for a modern engine and 15% nitro.
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Castor oil is still better than two stroke oil made for gas and the smaller the engine the cooler it runs so, still doesn't explain why smaller engines need more oil.
MM
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Castor oil is still better than two stroke oil made for gas and the smaller the engine the cooler it runs so, still doesn't explain why smaller engines need more oil.
No, purely as a lubricant, castor isn't particularly good. It has some other good properties but mostly it'a matter of cooling in iron-liner engines. See Randy's pinned topic in the engine forum, it will give you some basics.
Brett
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I have been running my old spark ignition motors on Coleman stove fuel and 25% Walmart SuperTech 2 stroke oil. They run pretty cool and no problems so far anyway. The engines run much cleaner than with castor alky.
Hi Kevin. Sometimes the jugs are so full that you cannot add much. I pull maybe 8 ounces out and replace it with 8 ounces of castor depending on how much oil you want. Then 20% of 120 ounces is 24 ounces of oil. Add 8 more ounces of castor to make 32 ounces of oil in 128 ounces again. That would give you 25% oil which would be good for old iron. But yes, we do run lots of oil compared to all the big 2 strokes.
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This is why i asked the experts. Got my answer and more. Can't know too much.
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Hi Jim!!
I run Colman fule ( white fuel) in my old Matag washing machine engines. It's a slick fule on its owne. I use Klotz super techniplate in every two stroke I run. Goes back from racing dirt bikes. But one question I have never asked with the Matag engines is what kind of oil did they use at that time. My engines date in the same area as your old Sparkys. Do you or anyone else know?
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There has been a lot of discussion on what the Maytags ran for fuel mix originally, but the most often quoted fuel was 16 to 1 30 wt. non detergent motor oil. Many are using that for running their Maytags and it seems to work well. There are also some running non premix 2 stoke oil at the same ratio. Maytag engines are cool.