RC Fuels Nitromethane, Castor Oil, Synthetic, heli fuel, 4 stroke, etc...Fuel Q&A is here!

Substitute nitromethane

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Old 12-01-2007, 04:38 PM
  #51  
Jezmo
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Default RE: Substitute nitromethane


ORIGINAL: Sport_Pilot

I would suggest that perhaps nitro *can* allow you to tune an engine to run cooler (by richening it up a whole lot (beyond the ideal stoichometric ratio) and thereby sacrificing some of that extra power for lower running temperature), BUT, if you tune for max RPMs then your engine *will* run hotter. Here's some supporting evidence.
If you were to run 100% nitro as in a dragster then the richer you run it the more power it will make, this is true till the spark cannot ignite the mixture. One of the major increases in HP in these engines is the development of huge electronic magnetoes which allow the mixture to be run richer. If you watch the competitions you will see raw wet fuel come out of a missfireing cylinder at the starting line. Looks almost like water running in spurts from a garden hose. When you run 25% or greater nitro then it will run cooler at peak power, but it will get much hotter than low nitro if you have a lean run.
Sport I know you have probably seen the mags being tested but I was amazed when I saw it for the first time about 15 yrs. ago. They had one of the distributors in a tester that could spin it to any rpm needed. They had the coil wire attached to an old spark plug screwed into an aluminum stand with the end facing out where I could see the firing. The air around the end of plug looked like it was on fire and when they stopped spinning the mag. both electrodes were glowing bright red. We're talking almost welding current here. If that hit you you would be DEAD. He said the voltage wasn't any higher than a stock ignition but the current was much much higher. (He told me how many joules it was but I've slept since then and can't remember) I guess you can tell I was quite impressed. Never had anything like that on any of my oval track cars.
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Old 12-01-2007, 07:38 PM
  #52  
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Default RE: Substitute nitromethane

Never had anything like that on any of my oval track cars.
I wouldn't think it would have gained any power in a pure alky or gas oval track car. Once the spark is hot enough to light the fire at maximum pressure there is no or little benifit. But the air fuel mixture in a nitro dragster or funny car is as much liquid as air and very hard to ignite. Increasing the power of the mag means more power because they can run a richer mixture and since nitro can burn without air, then the richer the more power.
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Old 12-01-2007, 07:55 PM
  #53  
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Default RE: Substitute nitromethane

The only drawback to using more nitro is that your engine will either melt or explode, with the explode event occurring more often than the melt event.
This is not a complete explanation. The nitro dragsters explode and melt parts a lot, but it is not because it burns hotter. Explosions happen for many reasons, detonation, faulty pistons which fracture from the extreme pressure, backfires into the supercharger, blown headgaskets, excessive blow by and ignition of that fuel in the crankcase, and even excessively rich mixtures causing hydro lock. The NHRA has limited the mixture to 90% nitro from 100% by rule but this still happens a lot. The melting is usually caused by detonation from using too high of a ratio on the superchager, or the timing is too advanced. Sometimes a lean run caused by debris in the fuel system can also cause parts to melt. These engines have no cooling system, the nitro mixture is so rich it just doesn't need to be cooled. The fuel evaporation is enough to carry the heat away, that and the cooler temps of the extremely rich mixture. Most of these engines are aluminum block, heads, and pistons. So it doesn't take much to melt these parts. The very extreme pressures, torque, and power is the main reason nitro racing engines don't last but one run and require teardown between each run.
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Old 12-02-2007, 07:19 AM
  #54  
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Default RE: Substitute nitromethane

Much as drag racing nitro is interesting especialy when you buy 55 gallon drum and get it for ~$15 ~11 euros USA gal or ~$18 ~15 euros a gal Imperial it still leave the probem that nitro for modelers usualy much more expensive for mdellers outside the drag racing circuits

Undersatanding what nitro does can help to replace it or reduce the amounts so as to give moddelers options

So I take pragmatic opinion
for motors below 4cc just order the stuff with relevant nito as its makes tuning motors so much easier and doubling fuel costs on small motors is often no big deal

for motrs from 4cc 25 class to motors 120 class 20cc running on 5% nitro will make tuning more easier than zero nitro

after 20cc then realy the motors can be made to run without nitro and will often save interesting amounts of money

however as tuning will vary with temperature and humiity each motor start over a day will often require retunning for each new humidity and temperature as the day progressses where often the higher nitro tuned motr will probably remian with the same tunning all day long

Other than some increase in power sometimes not worth the cost or hassle and ease of tuning ideal solution for novice or non mechanical types like me higher nitro if you can afford it makes life more easy but nitro is replaceable with other nitros in the nitro family or if no nitro is avavailble localy other solutions flike acetone etc exist and if your mechanical type with good tuning abilities then no nitro is a possibilty

Nitro where I am is ~45 euro $60 a imp gallon 4.5 litres aprox or 40 euros $50 a USA gall so it is not cheap here and often if available in LHS in europe is costing closer to 80 euros ~$100 a gallon imp or some $80 usa gallon

EEEEEKKKKKKK if your doing 30% nitro 3d 60 heli

generaly it ok if your doing nitro (25%volume usaa measure 16% weight weight measure Europe) for 1cc cox or novel or tolerable even for bigger 2.5cc RC car motor

Acrobatic planes that use mostly 1/3 throttle for motor run in flight on zero nitro and with extra nitro drop to mostly 1/4 throttle for motor run in flight will probably not notice the extra fuel costs so much as say a 3d heli which is mostly using 34/5th gas with low nitro and 3/4 on high nitro where the costs could easly quadruple

You look the prices to import with mail and HAZMAT and you can double or quadruple nitro costs easy so what you fly or use and what your wallet can afford and what your mechanical abilties are factors that all help decide the best response for each modelers unique problem

but for most Nitro users in USA the costs are far less and so they might find a 30% nitro 60 motor 3d heli acceptable where in europe they will often change to a 90 motor with tuned pipe and 5% nitro

I also expect fuel prices to surge to unreasonable amount even though methanol is made from natural gas and nitro is made from propane or gas as the rip off factors kick in like rising transport costs rising oil lubrication costs and fuel price gouging factors that always seem to happen and for methanol to follow oil prices upwards even if natural gas prices stay low or even go down (go figure)

however historicaly severe fuel price spikes tend be followed by long periods of declining fuel prices and history seems to always repeat itself so the quess is yours which way long term fuel costs will go


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Old 12-02-2007, 09:12 AM
  #55  
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Default RE: Substitute nitromethane


ORIGINAL: Sport_Pilot

Never had anything like that on any of my oval track cars.
I wouldn't think it would have gained any power in a pure alky or gas oval track car. Once the spark is hot enough to light the fire at maximum pressure there is no or little benifit. But the air fuel mixture in a nitro dragster or funny car is as much liquid as air and very hard to ignite. Increasing the power of the mag means more power because they can run a richer mixture and since nitro can burn without air, then the richer the more power.
Yep, spent my whole life making power out of ICE's. Funny just how much can still be learned after we have been doing this for over a hundred years. Your second sentence is only partly true but I don't want to get into a discussion about why so I'll just say have a wonderful day Sport. Catcha later.
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Old 06-22-2009, 09:14 AM
  #56  
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Default RE: Substitute nitromethane

What about KNO3? Can Kno3 disolve in methanol?, it can very well in water and methanol is very higroscopic so some % of methanol is water. Kno3 will give quite alot oxygen.
Or NH4NO3
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Old 06-22-2009, 12:39 PM
  #57  
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Default RE: Substitute nitromethane

Ammonium nitrate and saltpeter are solid oxidizers that do not mix with our fuel.  They won't burn and (at least ammonium nitrat) may requre an explosive charge more potent than the flame front of burning fuel. 
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