Fuelman

My Feedback: (6)

Folks,
This FAQ thread has not seen much activity in a couple months.

How about a few questions from some of our newer members or folks surfing through. Or, if you have a subject area (fuel related of course) that you would like a little further insight into, please feel free to ask.

As I mentioned in post #1, I will do my best to answer any an all of your questions with fact. I will contact other experts in the field to answer a question if necessary.

Thank you for visiting the forum.

shortan

can any one help me im looking for the proper mixtures and the place to get the ingredients from, for 20% thanks shawn

noahb

My Feedback: (67)

here is a question, and a possible answer to the coil in the exhaust side of the pressure tubing on cars. First the question...
I run coolpower (total synthetic), never had a problem with any engine I have ever owned, and all have great compression. I know that castor is added insurence, not to mention rust prevention. My question is this: What is the big deal about all syn. fuel? Some people will not run this fuel cause of concer about there engines. Please shed some light on this as I have never had any problems in my engines, they are very clean inside, great compression, and run great. This includes four strokes.
Now the other issue...the reason I here for the coil in the exhuast side is to help dampen pressure pulses to the carb. Cars are driven with lots of throttle action. I don't know if this is the case or not, but it's is what I have heard.

elmote

Fuelman
Thought Id ask your opinion-
I broke my tt70(heli) in on coolpower red (30%), but want to switch to green(15%) to save money/fuel. I had about a pint of red left in a bottle with some oil additive, dumped this into a 3/4 full bottle of green. Mixed up, looks like chocolate milk in color! I closed the main needle several turns but left the idle where it was. Engine starts and idles well, comes up to speed nice, but after a minute or so in hover abruptly dies. Tried lots of variations on the needle, kept happening (about 12 times). I plan to try some pure green today. Running OS8 plug. Any suggestions? Is this fuel ruined?

Elmo Te

thojo

I am envolved in R/C combat and we are flying a new class called "SSC", or "Slow, Survivable Combat." This class uses stock .15 engines with a retail purchase price of $60 or less. The 2 most common engines being the OS LA15 and Magnum 15XL. Also of importance, we use an 8x3 prop and mandate a maximum RPM limit of 17,500 to decrease the maximum possible speed of the planes to increase survivability. Planes must weigh over 2.5lbs.

We try to get our engines as close to 17,500 without going over to get the best performance out of the planes. During the winter months with cool dry days, this limit is easy to reach, but with the summer months with heat and humity, this limit is hard to reach.

Do you have recommendations for a "summer fuel mix" and "winter fuel mix" to maximize the potential maximum RPM's with these little engines?

Fuelman

My Feedback: (6)

Folks,
I just got back form a short vacation. I'll get to your questions within the next couple of days.

Fuelman

My Feedback: (6)

Noahb;
First the question...
"I run coolpower (total synthetic), never had a problem with any engine I have ever owned, and all have great compression. I know that castor is added insurence, not to mention rust prevention. My question is this: What is the big deal about all syn. fuel? Some people will not run this fuel cause of concer about there engines. Please shed some light on this as I have never had any problems in my engines, they are very clean inside, great compression, and run great. This includes four strokes."

Noah-
People that have a concern regarding an all synthetic fuel in most of their engines are mainly concerned with maximizing the protection available to them. I don't think that anybody will argue the point that an all synthetic fuel will run fine and protect just adequatly in a large number of engines. One of the points about castor is maximizing protection in a large number of engines and an absolute necessity in others. Castor will do a few things better than most of the synthetics used in glow fuel out there. Castor is the best rust inhibitor that we can use in a fuel and it offers a considerable protection advantage when a lean run occurs (does'nt burn up like the majority of synthetics used). Castor oil will stick around much longer when a hot condition (lean) happens because it does not flash off like most synthetics out there. This is important in the ABC type engines that need the cushion between the piston and sleeve, not to mention non ball bearing engines that rely on a film of oil to keep the crankshaft and bushing from contacting each other.One benefit to castor (even in small amounts) that many folks do not realize is the excellent protection of the large end of the connecting rod and crank pin. It's generally not as slippery as several of the synthetics but it does have a lot of "cushion".
Very few synthetic lubricants used in glow fuel today will survive a hot run where castor will. A little bit of castor (2% to 4%) in most of todays four stroke engines will not hurt them a bit, although many folks now run total synthetic in four strokes.


"Now the other issue...the reason I here for the coil in the exhuast side is to help dampen pressure pulses to the carb. Cars are driven with lots of throttle action. I don't know if this is the case or not, but it's is what I have heard."

Noah- Not being a "Car" guy, I can only look at data that I can collect and based on the experiment that I performed outlined in a post near the begining of the thread, I can say that I saw no measurable difference. Hey, if the car folks think it helps, thats great.

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Elmo Te:

"Fuelman
Thought Id ask your opinion-
I broke my tt70(heli) in on coolpower red (30%), but want to switch to green(15%) to save money/fuel. I had about a pint of red left in a bottle with some oil additive, dumped this into a 3/4 full bottle of green. Mixed up, looks like chocolate milk in color! I closed the main needle several turns but left the idle where it was. Engine starts and idles well, comes up to speed nice, but after a minute or so in hover abruptly dies. Tried lots of variations on the needle, kept happening (about 12 times). I plan to try some pure green today. Running OS8 plug. Any suggestions? Is this fuel ruined? "

OK Elmo, you have me wondering what "oil additive" you are refering to?
Mixing CP30 and CP15 would not necessarily do any harm, but if some other foreign matter that does'nt belong, well, I don't know.
As far as the needle settings, if you were running CP30 it is going to be a richer needle setting that if you were running CP15 (if tuned correctly). Now switching to 15% will be a little leaner than the CP30, but I can't believe that it would be "several turns" leaner.
My suggestion is on the conservative side: Set the engine at the factory recommended needle settings and get a fresh gallon of the fuel of your choice. It is always better to be a little richer than optimum instead of leaner. You may want to consider putting in a new glow plug too, have no idea what your "chocholate milk" did to that too.


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Thojo:

"We try to get our engines as close to 17,500 without going over to get the best performance out of the planes. During the winter months with cool dry days, this limit is easy to reach, but with the summer months with heat and humity, this limit is hard to reach.

Do you have recommendations for a "summer fuel mix" and "winter fuel mix" to maximize the potential maximum RPM's with these little engines?"

Thojo,
The performance drop you experience is because cool dry air can pack more fuel in it than hot moist air. the hot moist air has another affect- your prop is less efficient. I have no idea what fuel or nitro percentage you're running now but you may want to play around with running a little more nitro or a little less depending on what engine and fuel your running now.
As far as anything specific, I can't offer what you probably want.

BigSTIK40flier

for those who need to know, as far as i know all pink fuels are more castor based, all green or other colors should be all synthetic or more sythentic blend than castor

elmote

Better re-research that one!
Pink/red is usually the high nitro, and green the low nitro. Doesnt reference oil at all. To wit: see Wildcat advert on back page of latest issue of MHT. Synthetic oil is touted on the label of BOTH colors, only nitro content differs. Same is true with Morgan/Cool Power.

Elmo Te

BigSTIK40flier

well i might be wrong, but here in Texas, ive seen 5%, 10, 15, nitro% in red and green, and the color for the synthetic is always green, and red/pink is always castor based(not always pure castor). but i might be wrong but i dont research that much i just go by what the pattern seems to be. and i usally see GREEN in 15 % by morgan fuels cool power which is all synthetic, and Morgan fuels omega fuel is pink is a blend,and is avilble in 5- 15% so i guess nobody really knows then

elmote

Perhaps it changes regionaly as well as nationaly. Here in CA we see mostly CP green 15% and red 30%, both synthetic.

Elmo Te

Fuelman

My Feedback: (6)

Gentlemen:
The color of the fuel has absolutly no bearing on what the contents are since there is no standardization in the model fuel industry. Each company has its own method of doing things and colors its fuel the way it pleases.
For instance, every blend except one that we make is dyed a very light red, just enough for the heli guys to see it in the tank, the all castor blends we make are a light amber because of the castor which is its natural color and it immediatly identifies that as an all castor blend.
Bottom line is, any fuel company could dye their products any color they want for any reason and it has no indication to the contents of a different manufacture's fuels.
The best bet is to read the labels to identify the contents.

elmote

fair enough

Elmo Te

HobbyBob

Fuelman -
Need some help making sense of this.
I recently moved from a 1/8th on-road car to a 1/10th stadium truck.
Now in my on-road car I was running Blue Thunder 10% nitro (no idea on the lubricants). Anyway the on-road car is really old and finally broke where I can not replace the parts. This happened in March. I had about 3/4 of a Gallon of fuel left. Now last month I got a new stadium truck and decided to run the fuel I had, and for the most part the Truck has been running great. This weekend I was running a slightly hotter and dryer climate than usual. The first thing I did was add 1/8th turn to the high needle.
After the first 1/2 tank of fuel my engine over heated 304 degrees (I know, NOT good for my engine). I continued to chase my needles around looking for a setting that would prevent the engine from overheating. By the time I got there, about 250 degrees average, the performance was horrible. Transition from idle up was boggy and sluggish. (I should mention that the entire time running, even when I over heated, the engine was pumping loads of blue smoke).
I ran out of the 10% fuel, and the only car fuel available was 20% Blue Thunder, so I picked up a gallon. Anyway I started running this fuel without touching my needles.

- Now for the strange part ?

With the 20% my head temp dropped from 250 +/- 2 degrees to an average of 230 +/- and the engine cleaned up during transition.

This is the part that I can not put together. Higher nitro --> hotter burn, what could make it run cooler?

Could the fact the 10% fuel was about 6 months old cause it to run hotter? I am always careful about my fuels, Dark and Cool. When I need fuel I transfer from the 1 gal jug to a quart jug so the main fuel doesn't get exposed to the air/moisture as much.

Any thoughts on this would be helpful.

HobbyBob

Below is a exerpt from Ron Paris's web site on the usage of coiled lines from the muffler to the tank.

"How does the pressure line length effect performance -:-
A longer line "can" lean out the midrange when the throttle is applied rapidly! Keep in mind pressure is self equalizing [the tank and pipe pressure will be the same] The only consideration is if the pressure feed line is restrictive, [i.e. long length or small diameter] it can delay the time it takes the tank to reach maximum pipe pressure. Pressure dictates fuel flow at any given needle setting, therefore a leaner midrange can result!

There is no ideal length, this is something you can experiment with, In most case's 8" to 14" is common. This is something I would not concern my self with until you have completely mastered the art of tuning the standard low and high-end needles.

Line length has a very small effect by comparison and should be considered "fine" tuning. "

There is excellent information on this site

http://www.parisracing.com

Fuelman

My Feedback: (6)

Hobby Bob:
Thank you for the info regarding the pressure line, maybe this can be put to rest since that sounds like a reasonable answer.

Why can higher nitro percentages run cooler than lower you ask?

-When higher percentages of nitro are used (assuming that the oil contents are identical), the needle must be richer than lower nitro content fuels. With a richer needle setting, more fuel is consumed which means more oil, methanol, and nitro is run through the engine. Methanol has a very dramatic cooling effect when run through our engines, nitro has a fairly good cooling effect and the additional oil does not hurt either.
The most probable reason that your engine ran fine without needle changes when you moved from the 10% to the 20% is that you were too rich on the 10% in an effort to reduce the operating tempreture.


When you were hitting 300 degrees, how was the engine running?, You should not have a problem running at higher temps if it is not too lean. For instance, while testing a new car engine coming out on the market soon, we saw some high operating temps, well above 300 degrees, and we were still rather rich. When properly tuned, we saw mid 300's on gallon after gallon and running it as hard as we could, nearly non stop as long as the batteries would hold out. This engine was tortured, as hard as any driver could and it never flamed out or overheated or was run lean. An abundance of power was always present. After a lot of fuel (gallons, not tanks), the engine still had like new compression! We did not even change the glow plug once. On a few runs using a traditional high oil airplane fuel, we recorded temps over 400 degrees and was still putting out power without being lean. The moral to the story is that you should tune your engine to where the mixture (high and low speed) is set according to the conditions encountered (fuel, altitude, gear ratios, air temps, etc..) without setting it lean. Heat makes horsepower as long as heat is not caused by over lean mixture settings. If you did not have a temp gun, you would have tuned your engine according to the conditions and may have never noticed that it was running higher than what some folks consider normal.


As far as why your engine ran the way it did on the 10% fuel you mention- I can not give you a definate answer on that, a lot of variables are involved that would prevent me from being able to get specific. If you want to shoot me an e-mail with some specifics, I will do my best to answer your question.

HobbyBob

Fuelman, thanks for the post makes total sense to me. I think I understand what happened to me. I am pretty sure I hurt the engine though in a leanout yesterday. I was ripping it up and everything was running great and then the engine just shutdown. Checking over the engine I found that the high needle housing / fuel inlet fitting had come loose. Didn't seize up the engine but the plug was burnt out and now turning the engine over by hand, the compression just feels lower than it should. Might be my imagination but I don't really think so.

Thanks for the help though.

Bob

Imac Kiwi

Hi Fuelman

Just a query on oil content for larger engines.

Supertigres larger engine range use 12% oil. I have been told the Mokis use a low oil content also. OS for the 1.60 recommends 18% min oil content by volume.

Can you shed any more light on this subject? as most of these engines operate normally in the sub 10,000 rpm range.

Any help appreciated
Alan

Fuelman

My Feedback: (6)

Alan,

Yes, it can get confusing.

The big 'Tigers and Moki's are very high compression engines and tend to favor blends that will not over compress the engine or pre-ignite. The OS 160 is a much lower compression engine made to tolerate the higher nitro percentages. What's all this mean?

If you have a high compression engine they like zero or low nitro fuels to run correctly, well in the case of the Big Tigers, low or zero nitro in some cases is not enough. To further reduce the compression occurring inside the combustion chamber you need to remove oil. Why oil? Methanol when atomized by the carburetor is for the most part becomes very compressible where the oil will not compress because it will not change state (liquid to gas). Removing oil has a similar effect as decreasing the compression ratio. This is for the most part done to keep the engines from pre-igniting the fuel mixture.

Now to complicate things; A big Tiger can successfully run a higher nitro (10% to 15%) fuel and higher oil (15% to 20%) fuel, if you can find a glow plug cold enough to keep the fuel from pre-igniting in the combustion chamber. The needles get a bit sensitive on it though.

With the big Moki's, similar story, however after the first couple gallons of higher oil fuel (18% to 20% oil), still at zero nitro, I like to run them around 15% total oil with a Castor / synthetic blend.

The OS 160, being a lower compression engine will run just fine on zero nitro and high oil, once properly tuned and will run and last fine on my Moki blend of zero nitro with 15% oil. Being an engine designed for some nitro, they run much stronger with a little nitro. Most folks with the 160 are probably running between 5% and 15% nitro in them. I know a few guys running 25%. As far as oil contents go for the OS 160, I have never ventured lower than 15% with them, but never needed to because they performed fine on standard off the shelf blends.

Keep in mind that although we're talking about lower oil contents in this particular post, your fuel company is not going to warranty engines. Only the engine manufacturer or distributer will warranty them and they have good reason for their oil recommendations.

downunder-RCU

Fuelman...I have to disagree that lowering the % of oil has any noticeable affect on the compression ratio. It was discussed in another thread at
http://www.rcuniverse.com/showthread...7&pagenumber=2
where posts 29 and 30 both showed that the volume of oil in the combustion chamber was on the order of 2000 to 3000 times smaller than the volume of the combustion chamber itself. This was based on 20% oil and even if you upped the oil content to 40% you'd still have a combustion chamber volume that was at least 1000 times larger than the vol of oil..

3d-aholic

My Feedback: (7)

Fuelman: I have some more questions:

What kind of secondary "synthetic" lubricant should I be using. I'm use to 100% castro....but it seems most folks are using Synth + Castro mixed. I see Klotz recommended the most...is that the best synth.? Also there are several kinds. World Wide sells something called World Wide Lubricant sold by World Wide Racing fuels? Is this just Klotz?

What about Power additives. WorldWide also sells a power additive called Super Blue 007....should I be using this in a day-to-day model fuel?

What about Propylene Oxide...is that something I should be mixing in as well? Is the same thing as Super Blue 007?

Fuelman

My Feedback: (6)

2 Much Throw:
As far as synthetics are concerned, many are suitable. Klotz is widely recommended on these boards because it is widely available.
Keep in mind that many fuel companies, S&W, Cooper's, Morgans, Sig, and probably a few others sell synthetics and castors for the home-blenders, so Klotz is not the only game in town. I have no idea what lubricants or additives World Wide Racing sells, so I can not comment on them.
As far as power additives, I am a firm believer that nothing but good methanol, good lubes and good nitro is the best way to achieve good power in the modeling engines. Power additives do exist, but every one that I know of has some pretty undesirable side effects like extremely dangerous to handle, extremely volatile and some are even carcinogenic. Propylene oxide is expensive, very dangerous to handle, extremely volatile, etc, etc.. I stay away from it and refuse to expose my customers to it.

I saw in your other post the question about fuel fragrances. "The Original Nitro Scent" is the only one I have experience with, but there are other similar products out there. You can add it to the fuel or the oil if you desire the exhaust to have a different fragrance.

I hope this helps.

Fuelman
Cooper Fuels

3d-aholic

My Feedback: (7)

Thanks Fuelman. I checkout out Sig...and they are reselling Klotz. Morgan says buy the homebrew stuff at the hobby store...and none of ours have this stuff. Can't find a website for the others...

This is the world wide stuff...its one of the best prices I've found.

http://web.iwebcenters.com/worldwide...item83681.ctlg
And look at this

World Wide Lubricantâ„¢ 12 oz. bottles (24 or more)
Blue and clear available.
Availability: 12 oz. bottles, 1 gallon cans.
Manufactured exclusively by World Wide Racing Fuels.
Used for methanol and nitromethane.
Lubricates engines.
One 12 oz. bottle lubes 55 gallons of fuel.

Car racing fuel must have a very low lubricant requirement.....

Sport_Pilot

Give Morgans a call. They will sell their oils dirrect to you. $88 for a case of four gallons synth or castor, no shipping.

3d-aholic

My Feedback: (7)

Thanks I already ordered from Sig. 1 Gallon Castor, 1 Gallon Synth for $62 with shipping. Sounds like a better deal...Next time.

But their phone # is not on their website....