Oil Fuel Ratio
 

I am running 30 percent nitro and 11 percent oil, I want to increase my oil percentage 2 percent, total of 13 percent. How much oil (ounces) do I have to add to one gallon of fuel? I am not sure but I come up with 2.5 oz, is this correct?Are there any fuel specialist out there?

Using a prog called "Glowcalc" (glow fuel volume ratios):

Methanol 59% = 0,59 US gallon = 75,52 US fluid Oz
Nitro 30% = 0,30 US gallon = 38,40 US fluid Oz
Oil 11% = 0,11 US gallon = 14,08 US fluid Oz
Total 100%

Methanol 59% = 0,59 US gallon = 75,52 US fluid Oz
Nitro 30% = 0,30 US gallon = 38,40 US fluid Oz
Oil 13% = 0,13 US gallon = 16,64 US fluid Oz
Total 102%


Difference = 2,56
So you were correct :nod:

Thank you, I really was not sure of the amount,again thanks.

Ahhhh so much easier with metric ;)

You can't have a bottle with 102% fuel in it! :D

If you only add some oil, the methanol and nitro percent will drop.

1 gallon = 3,79 liter (l).
59% methanol = 3,79 * 0,59 = 2,2361 l.
30% nitro = 3,79 * 0,30 = 1,137 l.
11% oil = 3,79 * 0,11 = 0,4169 l.

Raise the total volume with 2,3%:
3,79 * 1,023 = 3,87717
13% of that volume is:
3,87717 * 0,13 = 0,50403
Oil you'll have to add:
0,50403 - 0,4169 = 0,08713 liter oil = 2,9462158 US fluid ounces

New percents:
Methanol = (2,2361 * 100) / 3,87717 = 57,67%
Nitro = (1,137 * 100) / 3,87717 = 29,33%
Oil = (0,50403 * 100) / 3,87717 = 13,00%

What oil will you add?


I bought 12 gallons of 16% fuel last year for close to nothing. To transform it to 25% nitro and still have the same oil percent, I'll have to add both nitro and oil.


Cheers :nod:

on +/- 4 liter of fuel adding 2% oil it is just 40cc, you can calculate a lot but adding such an amount of oil will come close to 2% more oil....

yes it is all greek to me. I am adding 2.5oz of oil to an already premixed gallon of fuel a total volume of 100% adding 2.5oz of oil increases the total volume of fluid to 1ga.2.5oz or 130.5 fl.oz. in which adds up to 102% of fluid. The oil I am adding is Blendzall 2cycle racing castor lubricant. If I wanted to make my gallon at 30%nitro,13%oil I would use less methanol 57%

why do you want soo much oil ? adding oil just forces you to run a leaner mixture to get crisp throttle...a lower oil allows you to run a richer mixture and still keep crispy throttle response.....Also more oil will make the engine run hotter.....Now for breakin I can see adding oil...But for racing 13% is too much IMHO, and in the end wont do your engine much good if you tune for performance.... thats my story and I'm sticking to it !

i heard the old rule of thumb is anything over 10% is a waste. and i would think it would gum the motor up and create way more heat

Ok you guys are right. I ran it the other day and did not have to tune the motor, it ran pretty good but it did run 15*hotter so about 245-250 degrees. I just wanted to ad (blendzall) to my fuel. I guess I will run 30%nitro w/9%oil and add 2.5 oz.of castor oil(blendzall) That would make it 11% oil. I am just experimenting with the oil. By the way I am running the OS .21XZB engine.

could be wrong but a well know engine guru told me anything over 8% is overkill

I wonder what Rolo Tomassi has to say about the % of oil?

you'll need less oil if you run 30% nitro compared to e.g. 25% nitro. That's a fact :)

Why buy 30/9% fuel and add extra oil, when you just can buy 130/1% fuel??

I am just experimenting with oil. Byrons fuels are available in 30% nitro 11% oil. That is what I run, I did notice the engine ran better at 13% oil but 15degrees hotter.

Yep
 

I think adding a very small ammount of castor oil is good. I wouldn't put 2 oz's in it. Probably 1/2 ounce. Most fuels with under 10% are pushing it. I like the 25% nitro 11% oil myself with a small ammount of castor just to make it perfect. especially during break in..I mix the 20% 16% with the 25% 11% sometimes. That works awesome for breakin......

Explain why?
Talking about oils in a wide sense is dangerous. The one oil has a much worse lubrication than the other. With other words, with some oils you need more to get a same lubrication than others.
For sure you can run on 6% oil or even lower without a problem but you will see the lifespan will be shorter and the change of a broken rod will be higher.
By the way, with boats and airplaines/heli some fuels contain up to 20% of oils

Also explain why?
You do need an amount of oil per stroke.
I can imagine the runtime on more nitro is less on a tank, calculating back to the amount of one stroke you could be right. On the other hand the more nitro will give more forces inside which does need more oil to deal with it.

Well :)

Nitro needs more oxygen to explode compared with methanol. An engine uses a specific amount of air at any given RPM. Now, to make the correct oxygen/fuel ratio you'll have to add much more fuel, when you run high nitro content compared to low nitro content. When you add more fuel (and oil), there will be a higher fuel flow through the engine = more lubrication. That's why you don't need the same amount of oil when you run high nitro content.

So I emailed the folks at O'Donnel and asked them if castor oil can/should be added to the Speed Blend fuel for better engine protection. Here is their response:

-Thank you for contacting product support. This fuel is designed for racing engines and provides a higher rpm. You can use a non speed blend fuel that has 18% oil content and runs as well. For*both fuels I would highly recommend using an after run oil to keep the engine clean and running longer.

Thanks,
Mike M.
Product Support Technician
Great Planes Model Distributers
PS9021

Didn't completely answer my question, but it gave me enough to make me rethink my earlier position.

Nitromethane is an oxidizing agent. The oxygen content of nitromethane
enables it to burn with much less atmospheric oxygen.
Please read all of the interesting info in the link below.
http://en.wikipedia.org/wiki/Nitromethane

Pretty much this.

14.7 lb (6.7 kg) of air is required to burn 1 lb (0.45 kg) of gasoline, but only 1.7 lb (0.77 kg) of air for 1 lb of nitromethane. Since an engine's cylinder can only contain a limited amount of air on each stroke, 8.7 times more nitromethane than gasoline can be burned in one stroke. Nitromethane, however, has a lower energy density: Gasoline provides about 42–44 MJ/kg whereas nitromethane provides only 11.3 MJ/kg. This analysis indicates that nitromethane generates about 2.3 times the power of gasoline when combined with a given amount of oxygen.

An engine sucks in a specific amount of oxygen when running. If it was a gasoline engine you would only have to add 1/14,7 gasoline to have the correct mixing ratio. With nitromethan you'll have to add nearly the same (1/1,7) amount of nitro to make it explode.

If you have tried changing nitro content you'll see, you have to retune. Lean the needles if you go from high to low nitro content and visa versa.

I attented in a race in 2009 with a RB WSIII and ran it 0% nitro, really high compression ratio and an OS 4 stroke plug! :D. The runtime with 25% nitro was only 7 min. With my fuel I could pit at 10 minutes due to the much leaner tune.

I emailed Byrons about adding oil to their fuel. Here is their response: I am not familiar with Blendzall oil. However, it this is a good grade synthetic oil that will blend with methanol, then you should be okay adding it to the mixture to increase the total oil content. One thing I will add is all our synthetic and castor lubricants are much higher quality than the majority of products available on the market and your 9% oil content in the Byron Fuel is probably superior to even an 11% total oil content of another brand of oil.



To be competitive on the open market, most oil blenders, Klotz included, do not provide the highest quality possible because to do so would price them out of the market. The Klotz oils we have in our fuel are higher quality than the Klotz oils available on the market and we pay the price for that.



So, if you add Blendzall to your fuel, you should do no harm. But I am not sure of the quality and I cannot guarantee adding Blendzall will increase the lubrication qualities of your Byron Fuel.



I hope this is somewhat helpful.



Best regards,





BYRON ORIGINALS, INC.



www.ByronOriginalsInc.com