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10 or 20% nitro? that is the question

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Old 01-06-2004, 08:50 AM
  #1
jayhawk25_2000
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Default 10 or 20% nitro? that is the question

Ok, My wife got me a sport maxx for christmas, I need to know the pros/cons of 10% and 20% fuel, I plan on using blue thunder.
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Old 01-06-2004, 01:36 PM
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Default RE: 10 or 20% nitro? that is the question

20% all the way. I can't think of any good reason at all to run 10%.
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Old 01-06-2004, 02:42 PM
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jayhawk25_2000
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Default RE: 10 or 20% nitro? that is the question

Why is 20% so good? I am fairly new to this and have a kyosho ultima st and have been running 10% in it for 7 months now.
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Old 01-06-2004, 02:52 PM
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Default RE: 10 or 20% nitro? that is the question

I always noted that 10% fuel oftern leaves a sticky residue . [:-]Where as I have never noticed this with 20% fuel as yet + you always have the fact that the stronger the fuel the more explosive this should mean more power.
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Old 01-06-2004, 03:18 PM
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Default RE: 10 or 20% nitro? that is the question

Normally, I'd agree with those that say 20%, as it IS a "more powerful" fuel.

BUT.....it also burns hotter, and according to Traxxas, if you live in a hot climate, you might be better off with 10%. I see you live in Florida, so it's gonna be a tough call. http://www.traxxas.com/support/faq/trx_faq_nitro04.htm

'Cause I also heard (at my LHS) that once you pick a fuel "strength" it's not good to switch!! If you start w/20%, you should stay w/20%. I don't know how "gospel" this is, but I'd still say start w/20 & see if you can keep the temps in the recommended range (buy a cheap Duratrax/Ofna temp guage!!!). I'm guessing if you DO have to switch, it's better to go from 20 to 10 than from 10 to 20!!

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Old 01-06-2004, 05:30 PM
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Default RE: 10 or 20% nitro? that is the question

higher nitro will only burn hotter if you dont retune if you retune it will drop youre temps I run 25% klotz I like it better than traxxas 20% droped my temp about 30 degrees and gave more power some manufacturers such as ofna recommend breakin with low nitro then switching to a higher nitro I would not buy less than 20% at all and I have run about 12 gallons this last year tried 20,30 and 25%
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Old 01-06-2004, 06:10 PM
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Default RE: 10 or 20% nitro? that is the question

I think however with methanol based fuel the bigger the % the cooler it runs.[X(] I can't remember, i read that or someone told me but it might be worth looking into..
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Old 01-06-2004, 06:36 PM
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Default RE: 10 or 20% nitro? that is the question

It all depends,if your rich forget 10 and 20 and go with 30,your engine won't last as long but man that truck will fly

if your not rich,like me,go 20 not as good as 30 but the extra power is worth if you plan to go offroad,10% just sucks with a capital S(in my opinion,i dont want to start an arguement)
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Old 01-06-2004, 08:06 PM
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Default RE: 10 or 20% nitro? that is the question

higher % nitro will make more power and run cooler if you tune it right. If you tune it to temps chances are you will lose engine life with the higher % fuel.
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Old 01-07-2004, 12:42 AM
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Default RE: 10 or 20% nitro? that is the question

The way I understand it is that the nitromethane is the most combustable ingredient in nitro fuel (nitro fuel is a blend of this and many other things including oil) and the higher the % the easier it is to ignite. This causes a slight advancement in timing, more violent explosion, more power, and more heat. Sorta like how an M-80 has more black powder in it than a black cat. Oil percentage has a lot to do with it to. More oil means less friction, less heat, and less power because it isn't combustable and takes up space in the nitro fuel blend that would otherwise be used for combustable ingredients.
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Old 01-07-2004, 01:25 AM
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Default RE: 10 or 20% nitro? that is the question

higher nitro cooler temp
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Old 01-07-2004, 01:40 AM
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Default RE: 10 or 20% nitro? that is the question

Why is that? I'm not saying your wrong, just curious. I noticed you run Klotz, I run Klotz oil in my Banshee and 250R (4-wheelers) and my snowmobiles. Klotz makes superior 2-stroke oil, maybe thats why your temps are low?
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Old 01-07-2004, 02:18 AM
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Default RE: 10 or 20% nitro? that is the question

I would say 10% would be the best jay!! because remember your engine will get hot anyways. 20% will only make it hotter! Just my 2 cents!!!
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Old 01-07-2004, 08:30 AM
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Default RE: 10 or 20% nitro? that is the question

20% will run a little hotter but at the same time give you a little more power. There is nothing wrong with 10% in fact, 10% is a little more safer to run with the added lubes. However, if you run 10%, stick with 10%. Once your engine is tuned to either 10 or 20, stick with that percentage or you may have problems. Another thing to consider, 10% nitro is generally $1.00 less per quart than 20%. Personally, my preference is 20%.

M87
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Old 01-07-2004, 01:39 PM
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Default RE: 10 or 20% nitro? that is the question

Quote:
ORIGINAL: ZAD

higher nitro cooler temp

WRONG!!
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Old 01-07-2004, 04:51 PM
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Default RE: 10 or 20% nitro? that is the question

deandome thats quite the statment when its not a fact and you obviously dont know if you state that it raises temps thats fine but people are asking why feed false info higher nitro can run richer which leads to cooler temps go try it and you would see thats a fact not my opinion . you didnt retune youre motor properly because thats the only way higher nitro will burn hotter
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Old 01-07-2004, 05:02 PM
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Default RE: 10 or 20% nitro? that is the question

Zad is absolutley correct !!! Higher nitro % will run at a higher rpm (leans out your motor) the cooler temps do come from richening up your needles. I fly competition helis and this theory is definately true. I run 35% in my comp helis and my ys.91 competion motor runs cooler than my YS .91 bash around the house motor. This is because i tun 20 % percent in my house heli to extend engine life , not so high rpms as the 35%. If you dont believe me i dont give a darn
call a fuel manufacturer and ask them. Don't throw out your uneducated opinions to someone who has no idea at all. All your going to do is mess this guys motor up. So go do some research before you post a bunch of nonsense!!!
Quote:
ORIGINAL: ZAD

deandome thats quite the statment when its not a fact and you obviously dont know if you state that it raises temps thats fine but people are asking why feed false info higher nitro can run richer which leads to cooler temps go try it and you would see thats a fact not my opinion . you didnt retune youre motor properly because thats the only way higher nitro will burn hotter
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Old 01-08-2004, 08:34 AM
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Default RE: 10 or 20% nitro? that is the question

heres a nice explanation i got from the fantom fr18 manaul.

Increased nitromethane content in the fuel causes combustion chamber temperatures to rise. This is normal since nitro is the
primary power-producing ingredient in the fuel’s chemistry. As the temperature increases, so does the expansion of the piston
and cylinder-sleeve. As described previously, the chrome-plated sleeve is engineered to expand more than the aluminum alloy
piston – as controlled by the cooling ability of the cylinder head fins. With higher nitro content fuels (e.g., 30%), the piston to
cylinder-sleeve running-fit (clearance) is a bit larger than with lower nitro fuel blends – it’s the nature of the beast. Therefore, if
you start by using 30% nitro fuel at the beginning of your engine’s life – with its tight pinch fit when cold – It will produce the best
possible WOT performance characteristics, if you continue to use the same fuel for the life of the piston and sleeve.
14 269. 649. 9583
If you change fuel – reduce the nitro content to say 20% - the engine will run good, but a bit of the pinch will wear away from
the top of the piston because lower cylinder temperatures equate to less expansion of the cylinder-sleeve. If you then decide to
switch back to the higher nitro fuel, the elevated temperature and expansion will produce greater piston clearance (due to its
previous wear using 20%); the elevated quantities of blow-by combustion gas will cause the engine to lose power.
These principles also hold true for oil content. By changing oil content, you may affect the temperature that the engine will run
at, which in turn will affect the piston / cylinder-sleeve clearance, as described above.
The moral of the story is: It’s best not to change fuel, once the break-in process has began, however, if you plan to switch fuels,
start with the highest nitro content and/or highest oil content and work your way down … never to return! Of course, there will
always be the individual that thinks the single fuel theory isn’t valid. After all, his engine runs faster with his latest switch to high
nitro content, until he meets-up with a single-fuel high nitro guy – who blows his doors off!
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Old 01-08-2004, 08:49 AM
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Default RE: 10 or 20% nitro? that is the question

Here we go again!LOL

Quote:
ORIGINAL: Ledgendary

This for all of you that "think" they know what nitro does or does not do and which one is best to use! This article will end the mystery for everyone!

by Steve Pond

PAGE ONE (OF ONE)


This article appeared in
the premier issue of RC Nitro.
This issue is no longer available.
The topic of RC nitro fuel sparks intense debate: how much nitro should you use? How much and which type of lubricant should the fuel contain? Will you get more power with fuel that has a higher nitro content? Can you switch to higher-nitro-percentage fuel without harming your engine? Is it a bad idea to switch fuel brands? These are legitimate questions, and a shortage of information adds to the confusion. I enlisted the help of Jerry Conley of Wildcat Fuels to shed light on fuel-related issues so that you'll be able to make an informed decision when you buy your next gallon of fuel.
Jerry has degrees in mechanical and aerospace engineering from Florida State University. He was involved in the development of fuel systems for the Air Force and the automotive industry and has consulted for the USAF, NASA, Nissan and Toyota. Jerry is president of Wildcat Fuels; his experience in the hobby industry spans 27 years.

The methanol used in most RC fuels is very pure and of a consistently good quality. Methanol is a fuel like gasoline but is less volatile yet produces more power; it also costs a heck of a lot more!

The nitro in RC fuel varies in quality; very pure nitro runs cooler and more cleanly than less pure nitro, and the difference can be significant. RC nitro fuels have a certain percentage of nitro mixed with methanol and lubricant. A gallon of fuel with 25 percent nitro is one quarter nitro; methanol and lubricant make up the rest of the mix.


FUEL BASICS

RC fuels differ most with respect to their lubricants. The lubricant (oil) is essential to keep the engine's moving parts working freely and to remove heat. Lubricants used in RC nitro fuel are either purely synthetic or a blend of synthetic oil and organic castor oil. A coating of oil prevents metal parts from rubbing against one another, and avoids heat buildup and excessive wear. The type, quantity and blend of lubricants in a fuel are the most closely guarded secrets in the business. A few manufacturers disclose lubricant content, but most of them leave you guessing.
Conventional wisdom says the castor oil promotes cooling while the more dynamic synthetic oil protects engine components from wear. Few fuels contain only castor oil; most contain either both types of oil or only synthetic oils.

The flash point?the temperature at which a lubricant will burn?varies with lubricant. Lubes with a very high flash point tend not to burn at all and leave the engine awash in oil. This certainly helps keep an engine well-lubed, but it can cause excessive oil discharge in exhaust. Lubes with a lower flash point tend to burn with the fuel, and this leaves a cleaner combustion chamber for the next cycle.




WHICH NITRO PERCENTAGE SHOULD YOU RUN?

This is an ?It depends who you ask? question; in fact, no fuel is ideal for every application. Nor is it a given that a higher percentage of nitro results in better performance. The correct percentage of nitro and its effects on engine performance are rather complex issues, but I'll try to cover the basics. To understand how nitro content affects engine performance, it helps to have a basic understanding of nitro. A derivative of propane, nitro can be considered an oxygenator; suitable as a fuel by itself, it carries its own oxygen component. Nitromethane contains nitrogen and oxygen, which provides more ?fuel? for the combustion process; more oxygen allows more fuel to be burned in the same amount of space. More fuel plus more air typically equals more horsepower?much like the benefits a turbocharger or supercharger give a full-size car engine. There is a great deal more technical complexity to nitromethane, but this explains why you can produce more power with it.




NOW, HOW MUCH NITRO SHOULD YOU RUN?

Maximum performance means an engine is running at maximum efficiency with maximum horsepower. The bottom line is that using high-nitro fuel that far exceeds the parameters of your engine may only net a slight gain in horsepower, but overall performance is compromised; so, more isn't necessarily better where nitro content is concerned.

When engineers design an engine, one of their primary considerations is the type of fuel to be used. The compression ratio and the timing and duration of the intake and exhaust ports take fuel composition into consideration. For example, Fed鲡tion Aeronautique Internationale engines?popular in model airplane competitions?are designed to run on pure methanol. The competition rules specify that fuel must not contain nitro. Adding nitro to the fuel used in these high-compression engines usually results in poor performance and high running temperatures.

Similarly, RC car engines are designed to run with a certain percentage of nitromethane. An engine designed to run on fuel with 20 percent nitro is configured for a certain compression ratio and a fuel/air ratio that provides ideal performance. Introducing a considerably higher concentration of nitro allows a greater overall amount of fuel volume. It can result in higher compression (air is the only compressible component in the fuel mix), detonation (when fuel explodes rather than burns) and higher operating temperatures. These outcomes show the fuel exceeds the design limitations of the engine. Even if none of these symptoms are patently obvious, combustion is compromised, and that prevents fuel from being completely burned. It can create an unstable idle and erratic fuel-mixture settings. These conditions are common in engines running on higher than recommended percentages of nitromethane. Essentially, the answer to the ?How much nitro?? question is that you should follow the engine manufacturer's recommendations.

There is a ?window? of about 5 percent both above and below the recommended percentage of nitro you can have in your fuel before engine performance will be noticeably affected. If a manufacturer recommends 20 percent nitro, you can get away with 25 percent. Go beyond that, and you are likely to wind up with an engine that runs hotter, gets poor fuel economy and is more difficult to tune. If your engine's manufacturer doesn't recommend a specific percentage of nitro, you may have to experiment to establish the proper balance of horsepower and efficiency.


CAN YOU CHANGE THE AMOUNT OF NITRO
IN FUEL WITHOUT DAMAGING THE ENGINE?

Yes and no. Yes, you can change the percentage of nitro in your fuel safely, but you must not make a change and run the engine hard right away. Every engine undergoes a process called ?hysteresis.? In hysteresis, the engine components slowly acclimate to the specific cylinder pressure and engine temperature that result from burning a particular type and blend of fuel. A change in fuel changes the whole picture for the engine. An engine that is accustomed to a certain amount of expansion using its usual fuel might now have to cope with increased cylinder pressures and the additional expansion caused by higher temperatures. Simply pouring a new fuel into the tank and ?letting 'er rip? places undue stress on the engine components.

If you use a different blend of fuel, your engine has to go through a second ?break-in.? Run the fuel mixture slightly rich and ease into the throttle for a few tanks before you nail it. If you fail to follow this procedure, your engine will still survive 99 percent of the time, but it will last longer and run stronger if you make a gradual change to a new fuel. There is also a break-in period during which using less nitro presents a new set of parameters for the engine.

STORAGE

Methanol-based fuel is hygroscopic. In plain English, that means it sucks in moisture like a sponge. If you leave the cap off a methanol fuel bottle for a couple of minutes, you'll see moisture accumulate inside the bottle, especially in humid conditions.

Since methanol also evaporates very quickly, it's important to keep the cap on your fuel and filler bottles. Even with the bottle capped, dramatic changes in temperature accelerate evaporation and moisture accumulation. If you have to store fuel, even for a short period, keep it out of the trunk of your car and off the cold basement floor. Try to keep fuel in an area where temperature remains relatively constant. If you must store it in a basement or garage, insulate the bottle from the floor with a piece of scrap carpet or lumber. If you are careful, and avoid conditions that make fuel go bad, you'll be able to safely store fuel and use it up to two years later!
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Old 01-08-2004, 09:31 AM
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Default RE: 10 or 20% nitro? that is the question

Very ncely said kimberklr hit the nail on the head
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Old 01-08-2004, 10:00 AM
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Default RE: 10 or 20% nitro? that is the question

I have tried it, you can believe me or not I really don't care. Higher nitro content will make your engine run at higher temps IF YOU DON"T RETUNE IT! You can run higher nitro richer because of it's higher % of nitro.

kimberklr, I say bah to that. I have gone back and forth between 20% and 25% for the last 8 gallons in my TRX 2.5. I have even run one tank at 25% and the next at 20%. We borrow fuel from who ever has the closest bottle when we are bashing around at the track. I don't even know if the fuel brands were the same. The point is, if you keep a safe tune on your motor you will get a decent life span out of it. Maybe I would have got 10 gallons out of my 2.5 if I hadnt switched fuel so much? To be honest, I was ready for it to die 4 gallons ago.
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Old 01-08-2004, 01:14 PM
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Default RE: 10 or 20% nitro? that is the question

yea i have a hard time figuring whats right all the time with everyones opinion.i believe you should do what works for you and stick with it.
about the silliest thing i hear in this hobby is tuning your carb by cylinder head temp???i realize that it is easy and it seems that most the industry has adopted it i just fail to see the logic in it.especially once you start adding aftermarket parts to your engine.a much more accurate way would be to measure exhaust temps.i believe tuning by power, sound,& smoke is much more accurate than cylinder head temp.traxxas says your engine should run xxx degrees over ambient temps,rubbish.in a perfect world when everyone had the exact same trucks,bodys,terrain,fuel,plugs,weather,ect.,ect it may work but in the real world it isn't logical.
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Old 01-08-2004, 05:44 PM
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Default RE: 10 or 20% nitro? that is the question

right arm
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Old 01-09-2004, 12:07 AM
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Default RE: 10 or 20% nitro? that is the question

Right arm........................what?.................. .......uh...........left arm?
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Old 01-09-2004, 12:17 AM
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Default RE: 10 or 20% nitro? that is the question

yep left and right makes a set .................................................. ........."right on"( for the layman)
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