I'm going to use Omega 5% in an engine that I'm porting and modifying.

I was never a math whiz. Dropped out of engineering school because of Calculus (differential equasions)[:-] i need a little help with a formula for calculating oil percentages.

The total oil content--as advertised by Morgan--is 17%. It's a 30/70 of castor/synthetic.

I want to increase the oil content using Klotz racing castor. I'm going to be experimenting with different percentages of oil up to about 25%.

How do I take a gallon of 17% oil and bump it up to a total content of 20%, or 23%?

I'll actually only be running a quart of the 17%. Then a quart of 18%, and then a qaurt of 19%--and so on. Up to maybe 25% total oil content.

So, a formula for turning 32oz of 17% into 18% would help a lot.

Thanks

22% oil is about all you want in there. At 17% there is 22 oz. of oil in the fuel. If you want to go to 22% oil content it's 22% of 128oz which gives you a total of 28 oz. So, add another 6oz of oil to get the total of 22% total oil.
Actually, this is not totally accurate because it leaves the nitro out of the equation.
Clarence Lee generally recommends 22% and it should, as you know, always include some castor since castor burns at a higher temperature than synthetic oil and protects against a lean run.
There is a better equation than this which is more accurate but this works fine. Just be consistent when you whip up your fuel each time. You may even want a couple of ounces less oil since it can and does get pretty messy.

3dbob

The way I've found easiest is to figure what volume is NOT oil and go from there.

For a first example let's figure a gallon that is 17% oil, and we want it to be 25% at the end.

17% oil means 83% alcohol and whatever, so 0.83 times 128 (gallon) gives us 106.24 ounces of fuel. Wanting this to be 75% of the final mix divide the 106.24 by 0.75, and we come up with 141.6533 ounces total. Subtract the 128 ounces we started with leaves 13.6533 ounces of oil to add, ending with 25% oil content.

Your quart of 17% has 26.56 ounces of "Fuel," that will be 82% of 32.39 ounces of 18% oil, so add 0.39 ounces of oil to get to 18%.

For 19% oil add 0.79 ounces of oil to a quart of the original 17% mix.

Finally, if you want to go from 17% to 20% oil add 1.2 ounces oil per quart of the original mix.

Bill.

To go from 17% oil to 22% needs 8.2 ounces added per gallon, or 2.05 ounces per quart.

These numbers are correct.

Bob:

Adding 6 ounces of oil to fuel that is alreaady 17% oil gives you 134 ounces total mix, and it's a little under 21% total oil.

Bill.

Hi Rcpilet,

Have a look at an Excel spreadsheet I posted some time ago:
http://www.rcuniverse.com/forum/m_16...tm.htm#1695391

It will calculate how much oil you should add.

/Red B.

Now IF I were in europe [>:], and one quart would be one liter, I would add 10cc (1%, or 1/3 Oz) of oil for every % oil increase, and forget about the slight increase in volume that might offset the exact %.
Hey, there is no midget in that engine measuring the exact oil content, and the engine does not notice these small deviations
to go from 17% to 20% would thus requires about 1 Oz/quart, which is close enough to the exact calculations of the previous posters.
I cannot help but be amused by the Imperial measurements. USA was supposed to go metric by 1967! What happened to you guys?

We happen to be BOTH at this time. What a confusing mess. You go to do work on your car and never know whether the nut is going to be metric or English? Even our model airplanes, have metric engines with English fasteners.

Metric is so nice.... Except when you need a 8M X 1.25 and all they have is 8M X 1. Or the 4mm screws are no longer than 15mm.

There's even a mess-up in our system with the #12 crews. Some young engineer will invaribly spec #12's for an application but no one stocks them. To get a few is special order and ten prices. Our system normally jumps from #10 to 1/4" leaving a gap.

Another problem is trying to figure whether it's 5/16" X 24 or 8M X 1?

Eventually you learn instant conversions from MM to decimal and fractional inches?

Enjoy,

Jim

Thanks very much guys.

I've got a couple temp sensors that my friend--an electrical engineer--hooked up to a digital display. I am going to mount the sensors on the engine to read temps during operation.

One sensor on the cylinder head, and one on the cylinder fins.

I want to see what effect the additional oil will have on temp and performance. I'm sure it will eventually reach a point of diminishing return. Thats why I wanted to add oil all the way up to 25%. I think at that point, the extra oil will just be wasted--or maybe even hinder engine performance.

I'm also curious to see how RPM are effected with higher oil ratios. I am thinking that I MIGHT see an increase in RPM initially--with oil ratios up to 20% or maybe even 22%--I'm just hypothisizing though. Eventually, I expect engine performance to actually diminish due to the higher oil ratios. I expect it to get harder to start with higher oil ratios--but thats just a guess.

This should be a sloppy and greasy experiment.

Again, thanks for the links and formulas.

I doubt you'll see any difference in revs from adding oil until you get to very high %'s. I run 25% all castor in my ST G51 and it starts first flick...every time....inverted....full throttle (except it doesn't have a throttle ). The temp readings should be interesting though.

I have a couple of little Java Scripts that you click on and they auto-run in MS Explorer. They will calc the new oil percentage and the amount to be added to get a percentage.

Drop me your e-mail and I'll send them to you.

yeah, in the old days 20% oil used to be a diesel team racing fuel, the oil taking op space that was better used for fuel. The tank allowed was a mere 10cc for 100 laps! The reduced oil content could just mean one less pit stop. I have seen diesels baked by this concoction, where 33% oil would leave them quite cool. Those were the days of cast iron pistons, but the main physics have not changed.
Ducted fan engines also run very well on 25% oil fuel. The big end needs it to prevent frying the crankpin.

"To go from 17% oil to 22% needs 8.2 ounces added per gallon, or 2.05 ounces per quart."

Are you sure? A gallon is 128 oz. so 1% is 1.28 oz. To go from 17% to 22% is a 5% change. 5 x 1.28oz. is 6.4oz. 1/4 of that is 1.8oz. What am I doing wrong?

Jim

Jim:

You are ignoring the increased total volume.

One gallon with 17% oil - 21.76 ounces of oil, and 106.24 ounces fuel component. The additiion of 6.4 ounces of oil leaves us with 28.16 ounces of oil in a total volume of 134.4 ounces. run the numbers yourself - 28.16 ounces of oil is 20.95% of the 134.4 total.

On the other hand, adding 8.2 ounces to the 21.76 then gives us 29.96 ounces oil in a volume of 136.2 ounces, 21.997% oil.

Forgetting that the total volume goes up as you add oil is where almost everyone gets messed up.

Bill.

Ah so! Thanks.

Jim

Go to this web page. Scroll to the lower part of the page. It will allow you to put in your current oil or nitro content percentages, and tell you how much to add to bring either oil or nitro to the desired content. It's a RC car web site, but the formula's are all the same.

http://nitrorc.com/fuelws/

John