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nitro % help

Old 06-01-2010, 11:36 PM
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Default nitro % help

Can some one explain the advantages to using a higher % of nitro I use 15% thank you
Old 06-02-2010, 01:14 AM
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Default RE: nitro % help

Too much nitro can cause problems that destroy your engine. What does the owners manual with your engine call for? 15% is the usual percentage for most medium sized 2 stroke glow airplane engines. Are you having troubles?
Old 06-02-2010, 07:07 AM
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Default RE: nitro % help

15% nitro is fine for most 2-strokes, and I also use 15% in my Saito 4-strokes. Higher nitro will give you a little more power and good for competitive flying. That being said, most Americans use far too much nitro. Overseas, nitromethane is often very hard to obtain, and in fact, illegal to possess in some countries. As many of you know, even in the U.S., it is more difficult now to get large quantities of nitromethane. After the Oklahoma City bombing, it is no wonder. With most engines, you do not get that many more rpm by going from 15% to even 30% nitromethane. That being said, many helicopter and Saito owners opt for heli fuels, with 30% nitromethane, and that is simply their choice. for top performance I buy nitromethane in 5 gallon pails, high purity methanol in 55-gallon drums and Klotz Techniplate oils in barrels for mixing fuels for helicopter, boat, cars and model planes. I do not mix up any high nitro fuels except on special request, and for boats. High nitro for boat racing is common, to squeeze out more power, and attendant shorter engine life. Sport car engines often do not have enough oil, consistent for longer engine life and good lubrication, some oils just 8-10% by volume. This is fine for racing, but a bit low for routine use. Most model engines will run on 5-15% nitromethane. With higher compression engines, and mostly overseas, engines are made to run on 0% nitromethane. Even these engines will idle better and transition to higher speeds and back down with a low level of nitromethane added. I hope this is of help to you. Enjoy your flying. The old fuel mixing dinosaur.
Old 06-02-2010, 02:08 PM
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Default RE: nitro % help

If your compression ratio is low then more nitro is more power, but with more consumption. If the ratio is to high it will just detonate or run hot. For most sport engines 15% is fine, and 20% about top. Some engines with lower compression can use up to 35%. But it costs a bunch and pours through the engine.
Old 06-02-2010, 02:09 PM
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Default RE: nitro % help

As many of you know, even in the U.S., it is more difficult now to get large quantities of nitromethane.
Actually its not. If you can afford it. It was short on supply a year ago, there is not restriction that I know of.
Old 06-02-2010, 02:53 PM
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Default RE: nitro % help

ok thanks for info im just trying to find out what kind of fuel i neewto be useing to get the most from my plane and air boat
Old 06-03-2010, 08:25 PM
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Default RE: nitro % help

I'm really pleased with how well my OS, Thunder Tiger and Enya 2-strokes run with zero% nitro. Unless you're willing to pay top dollar for a slight increase in power, consider running 5% or even zero.
Old 06-04-2010, 12:05 AM
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Default RE: nitro % help

In my experience I have found most average sized 2 strokes will probably run fine on 10 or 5 or even 0% nitro but you have to be willing to put in the effort to tune them for it and most flyers are not content fiddling with their engine when they could be flying.
Imyself love tuning up my engines to get the most of my combos. Ihave become the go to guy for tuning engines at my field.


Old 06-04-2010, 12:37 AM
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Default RE: nitro % help

I was going to keep out of this because the OP seemed intent on using as much nitro as possible but I'll back up what the others have said about using minimal nitro. I've never used nitro and all engines (I've lost count how many ) run perfectly well and I find them dead easy to tune. Sure, you can gain a bit more power with nitro but you can also gain almost as much by raising the compression way above what they have as standard but that's not really necessary.
Old 06-04-2010, 12:45 AM
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Default RE: nitro % help


ORIGINAL: jeffie8696

In my experience I have found most average sized 2 strokes will probably run fine on 10 or 5 or even 0% nitro but you have to be willing to put in the effort to tune them for it and most flyers are not content fiddling with their engine when they could be flying.
I myself love tuning up my engines to get the most of my combos. I have become the go to guy for tuning engines at my field.


same here
im running 0% and not having engine troubles at all, at first the tuneing is a little different but its not hard to adjust to 0% and is much much cheaper. the cost of nitro doesnt outweigh the benefits, my gms.47 will idle at 1650rpm all day on 0% nitro.
Old 06-04-2010, 11:24 AM
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Default RE: nitro % help

Honestly, once they are tuned to 0% they are no more trouble to keep tuned than with higher nitro. At least that is my experience. I do use hot plugs.
Old 06-04-2010, 11:53 AM
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Default RE: nitro % help

For example a flyer at our field was having trouble tuning his OS46AX 2 stroke. Ifinally managed to get him a decent running engine since he had the tdle mix way too rich(by a several turns) but then Ichecked his fuel, 25% nitro. Did the extra nitro help in this case? probably not since he had no clue how to tune an engine anyway. And his engine is getting beat to death by the high nitro, you can hear it .
Old 06-05-2010, 03:14 PM
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Default RE: nitro % help

funny you ask , i went in a hobby shop afew months ago and all they sold was 15%
Old 06-05-2010, 04:37 PM
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Default RE: nitro % help

Downunder gets it and might well agree that Americans in general use way more nitromethane than they need. I wonder if downunder uses a little acetone or other igniter in the winter there for a little easier starting. We used to use acetone, propylene oxide, nitromethane, nitrobenzene (Oil of Merbane), kerosene, you name it, to get faster speeds on model engines. We also got to find out what it takes to burn a hole in the top of a piston in rat racing and speed engines. :-)To me, one of the best benefits of nitromethane in reasonable amounts is a better, smoother idle and a little better throttle transition across idle to full throttle and a little easier starting. Despite what was said earlier in this thread, it is NOT easy to get large amounts of nitromethane. With Homeland Security and the drug manufacturing trade (illegal), I can't even buy a pound of iodine to treat my horse's foot. I practically had to leave my firstborn the last time I got a barrel of nitro. It seems that it was used in the Oklahoma federal building bombing. Even ammonium nitrate fertilizer is now tagged, and some will not blow up a stump. When bad people do bad things, the rest of us seem to pay along with them in some way. Except for racing and high performance work, I find that most engines will work just fine on 0-15% nitromethane, and for sport flying with many engines, 10% or 15% is just great. My experience is that, in general, a lot of folks are using high or very high nitromethane fuels, and fuels containing too little oil for the intended purpose. If you want to fly on the cheap, just mix yourself some FAI fuel and if you have a quart of nitro, add 5% to the FAI fuel and fly your heart out on your 2-stroke engines. The old FAI was 70/30 and the newer is 80% methanol and 20% castor. Oops, showing my age again! Just a few reflections from an old rat racer, combat flyer, free-flight and RC flyer.
Old 06-05-2010, 05:14 PM
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Default RE: nitro % help

Ithink people want to use nitro to cure their ill running engine. Its easy to fall into the habit. An engine with good idle and transition is sometimes hard to find what with all the cheap crap engines on the market. And a lot of guys dont want to learn how to tune, they set it once and forget it.
Just recently I had to turn the idle mix in a full half turn to overcome a rich idle condition because my engine is Finally breaking in. Had it been one of the less engine oriented fliers in my club they would have cussed out the engine for suddenly running bad and probably replaced it with another brand.
Iam trying to teach as many as I can the fine art of glow engine tuning.
Old 06-05-2010, 06:49 PM
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Default RE: nitro % help

ya like i may have said im new to this so i know very little about tunning
Old 06-05-2010, 11:06 PM
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Default RE: nitro % help

ORIGINAL: Fuel Dinosaur
I wonder if downunder uses a little acetone or other igniter in the winter there for a little easier starting.
I've used acetone at 3% occasionally but our winters are too mild to notice any affect. Actually I was wrong when I said I'd never used nitro because I've used it twice. The first time was with a K&B .15 in a rat racer for a state championship (which we won ) and later in a CL stunt competition held at a fairly high altitude where few of us had any experience with altitude. Australia is the flattest continent on Earth so most of our flying is probably at no more than about 1000' ASL. However these are the two occasions where nitro can help. Competitions where all out power is needed and to regain power loss because of altitude. For anything else, you need a bigger engine .

As far as tuning goes, nitro makes it easier for the simple reason that it's got a much wider range of tolerable mixture setting than any other fuel we use. The downside though is that it has to run far "richer" than any other fuel so the engine drinks it much faster giving shorter flight time at higher expense. One very slight advantage of high nitro (which to me means 15%) is that the higher fuel consumption allows more oil to flow through the engine which means manufacturers can put a little less oil in the fuel and still give the engine barely enough lubrication. However some companies (like Morgan) sell what they call FAI fuel (it isn't) with only 17% oil, the same amount as in their high nitro fuels. That's crazy because the oil flow is then too low for decent lubrication. Low or zero nitro fuel should have at least 20% oil.
Old 06-06-2010, 12:59 AM
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Default RE: nitro % help

But you cant tell the Morgans buyers their fuel doesnt have enough oil. We even have members in our club that swear it has 20% despite their own website stating it is only 17%.
Wouldnt it void your OS engine warranty if you used Morgans? Most of their engines call for minimum of 18%.
Old 06-06-2010, 03:12 PM
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Default RE: nitro % help


ORIGINAL: jeffie8696

Wouldnt it void your OS engine warranty if you used Morgans? Most of their engines call for minimum of 18%.
Most (but not all) 2-stroke engines do well on 18% oil, and engine manufacturers recommend this minimum level of lubrication for a very good reason. In order to reduce costs and maximize profits, many fuel companies are cutting the oil level and/or quality of the oil in their formulations. Not good. Castor oil is a great oil for 2-stroke engines and has been around a LONG time. It is a natural product and should be poured up and immediately capped and put back in a cool dry place, room temperature at the bottom of a closet is fine. I personally use 2-4% castor in my 4-stroke engines, but higher castor gums them up pretty much, so keep the castor low in 4-strokes. Here is a little information about castor oil. For model fuels, AA grade castor is fine, highly purified castor and castor with additives, like at the pharmacy, is less good for model engines.

Castor Oil is a natural oil obtained from the seed of the castor plant. It is unique among all fats and oils in that it is the only commercially important oil composed of approximately 90% of a hydroxy, unsaturated C18 fatty acid-ricinoleic acid.

Chemically, Castor Oil is a triglyceride (ester) of fatty acids. Approximately 90% of the fatty acid content is ricinoleic acid, an 18-carbon acid having a double bond in the 9-10 position and a hydroxyl group on the 12th carbon. This combination of hydroxyl group and unsaturation occurs only in Castor Oil. The primary sources of Castor Oil are from India, China and Brazil. Scientific and historical records reveal that regardless of origin, the chemical nature and composition are remarkable uniform.

There are two technical grades of Castor Oil: (AA grade castor shown here_:

Pale Pressed, also known as AA Standard, is obtained from the first pressing of the castor bean. Pale Pressed Castor Oil is lighter in color and lower in acidity. This is the one for your model engines.

Note added: Many modelers have an aversion to some castor film on their airplane after a flight, but I maintain this is good, it is the same stuff that is lubricating your engine well, especially sticking to the connecting rod and lower end of your engine, and yes, castor oil does reduce rust in your engine. Castor forms long chains during lean runs and further protects your engine and is not burned up like many synthetic oils. I personally use a blend of castor and synthetic oil for all of my flying and use only 10-15% nitromethane for most of my engines. The large ST engines will use 10-12% total oil and 5% nitromethane is plenty. The old style Cox engines still run well on 20-30% nitromethane, but with just a castor based fuel. Control line engines still generally run well on 20% oil fuels. For those who remember the old Fox .35, or better yet, still run one, 25-29% castor is fine. The old SuperFuel was about 29% castor and 5% nitromethane. Again, for Americans, in general, too much nitromethane and not quite enough oil is the rule. I have seen many an engine ruined by too much nitromethane, too lean a run, and too little oil, but seldom have ever seen an engine ruined by running too much oil. Maybe a very dirty plug and that is about it. That should tell you something.
Old 06-07-2010, 09:36 AM
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Default RE: nitro % help

Despite what was said earlier in this thread, it is NOT easy to get large amounts of nitromethane.
Next time order it on the web.

http://www.worldwideracingfuels.com/...?categoryID=70
Old 06-07-2010, 09:39 AM
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Default RE: nitro % help

That's crazy because the oil flow is then too low for decent lubrication.
IMO 17% is actually too high for modern ball bearing engines. I have heard of using 12% with no problems.
Old 06-07-2010, 07:04 PM
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Default RE: nitro % help


ORIGINAL: Fuel Dinosaur


ORIGINAL: jeffie8696

Wouldnt it void your OS engine warranty if you used Morgans? Most of their engines call for minimum of 18%.
Most (but not all) 2-stroke engines do well on 18% oil, and engine manufacturers recommend this minimum level of lubrication for a very good reason. In order to reduce costs and maximize profits, many fuel companies are cutting the oil level and/or quality of the oil in their formulations. Not good. Castor oil is a great oil for 2-stroke engines and has been around a LONG time. It is a natural product and should be poured up and immediately capped and put back in a cool dry place, room temperature at the bottom of a closet is fine. I personally use 2-4% castor in my 4-stroke engines, but higher castor gums them up pretty much, so keep the castor low in 4-strokes. Here is a little information about castor oil. For model fuels, AA grade castor is fine, highly purified castor and castor with additives, like at the pharmacy, is less good for model engines.

Castor Oil is a natural oil obtained from the seed of the castor plant. It is unique among all fats and oils in that it is the only commercially important oil composed of approximately 90% of a hydroxy, unsaturated C18 fatty acid-ricinoleic acid.

Chemically, Castor Oil is a triglyceride (ester) of fatty acids. Approximately 90% of the fatty acid content is ricinoleic acid, an 18-carbon acid having a double bond in the 9-10 position and a hydroxyl group on the 12th carbon. This combination of hydroxyl group and unsaturation occurs only in Castor Oil. The primary sources of Castor Oil are from India, China and Brazil. Scientific and historical records reveal that regardless of origin, the chemical nature and composition are remarkable uniform.

There are two technical grades of Castor Oil: (AA grade castor shown here_:

Pale Pressed, also known as AA Standard, is obtained from the first pressing of the castor bean. Pale Pressed Castor Oil is lighter in color and lower in acidity. This is the one for your model engines.

Note added: Many modelers have an aversion to some castor film on their airplane after a flight, but I maintain this is good, it is the same stuff that is lubricating your engine well, especially sticking to the connecting rod and lower end of your engine, and yes, castor oil does reduce rust in your engine. Castor forms long chains during lean runs and further protects your engine and is not burned up like many synthetic oils. I personally use a blend of castor and synthetic oil for all of my flying and use only 10-15% nitromethane for most of my engines. The large ST engines will use 10-12% total oil and 5% nitromethane is plenty. The old style Cox engines still run well on 20-30% nitromethane, but with just a castor based fuel. Control line engines still generally run well on 20% oil fuels. For those who remember the old Fox .35, or better yet, still run one, 25-29% castor is fine. The old SuperFuel was about 29% castor and 5% nitromethane. Again, for Americans, in general, too much nitromethane and not quite enough oil is the rule. I have seen many an engine ruined by too much nitromethane, too lean a run, and too little oil, but seldom have ever seen an engine ruined by running too much oil. Maybe a very dirty plug and that is about it. That should tell you something.
Nice summary Fuel Dino. I must be getting old because I love the smell of castor in the morning : ). I'm up here at 5300 feet above sea level so I use 15% nitro as opposed to the 5 or 10% I used to use at sea level. And whatever fuel I buy I bring it up to 20% with castor. Have 18 birds ready to fly and some of the engines are over 20 years old. Never a problem!

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