Nitro Methane fuels

[My2cents]

I was in a hobby shop the other day and noticed fuel for RC planes. The fuel was very expensive and there were 3 types. It came in gallon containers containing different volumes of "nitro methane" 10% 15% 20 %. I took a wiff of the fuel and it smelled like my Maxima 9272 stroke mix. Can any body shed any info on these fuels or this "nitro". I believe these RC engines run at extremely high RPMS.

 

[Tzed250]

Nitro

Nitromethane is an oxygen bearing fuel that is for use in high compression engines that are tuned to use the properties of nitromethane. Model airplane engines use between 5 and 70% nitro, 20% oil (often castor) and the balance methanol. Some turn over 30,000 RPM. NHRA Top Fuel dragsters use 90% nitromethane with the balance methanol to produce about 6500 HP from 500 cubic inches at about 10,000 RPM. Nitromethane can be used to produce incredible hp/cu.in. but practically the whole powerplant must be engineered around its use.

 

[Rotax Robert]

I have raced against guys that were running 10% in thier alcohol saws although I have never played with the stuff. Just for the record though ( this aint no B.S.) A friend of Birls and mine, Jason once ran menthanol in a 5 horse briggs and pulled something like18 hp. Then he ran 90% nitro and took another Dyno pull and got 58 hp befor the engine blew to smithereens. This guy does take his racing rather seriously as he runs a nitro injected dragster.

 

[BigJohn]

I've actually tried this once in my saw. I have an Rc truck pretty cool 4 wheel drive two speed trans disc brakes. But anyway I was playing around didn't have saw gas mixed and figured what the hell. It has oil in it so it work. The saw ripped! The only problem was it didn't want to shut down. I was even chokeing it. Maybe you could try mixing some in with your gas but not straight.

 

[husky394]

A nitromethane/alcohol mix is pretty much standard on modified saws around here. The problem is that a higher percentage of methanol is required, i.e. the mixture has to be much richer. This ususally requires some level of carburetor modification, to allow for the richer mixture. If this isn't done there is a serious risk of a lean siezure. I have tried the airplane fuel, and wasn't able to get the saw to run right on it, too much oil I think A mix made especially for hotsaws is much better. A colder plug may prevent run on.

I wouldn't recommend experimentation with the stuff in a good saw. I use an old Homelite for "research and development"

 

[cuttinscott]

Yea I used both 10 & 15% with carb mods, saws used were DOLMAR 116si & DOLMAR 166. The 116si loved it!!!!!! lightened flywheel, bumped timing richened carb big time. If adjusted right the saw actually runs cooler. The 166 ran good but because of limited old saw parts supply I never pushed that saw to see what she would really do. I'm a DOLMAR dealer (since 1980) & tuner a good friend of mine would race them at Tupper & Crogen. Maybe this season i"ll tune a DOLMAR PS7900 and see what it will do, they are hot right out of the box and selling real well. Later.................CUTTINSCOTT

 

[ccicora]

I would love to see you run the Delmars at Tupper Lake.... Good luck. Also you might want to see about Cherry Springs PA. Its about a 3.5 to 4 hr ride for you. I will be at Tupper and Cherry Springs so look me up.

Later,
Chris

 

[Rotax Robert]

Depending on what percentage of nitro being run, and (correct me here if I am wrong) wouldnt the only way to shut the saw off be to shut off the fuel flow?

 

[sedanman]

Top fuel cars run VERY high percentage of nitro , not 100% anymore but I think it's 90%. These cars use very expensive rare-earth magnets in the magnetos to produce a spark you could weld with! Nitro alone won't make youe engine a diesel, You have to have hot spots in the engine.

 

[Rotax Robert]

On my last trip back east to see DB. I asked him to run me to the store in his M5 which I think was on Nitro.

 

[sedanman]

I thought Babcock was on nitro. Gypo, well that's a chemistry class all unto its self. Me, I'm out of gin, ???? juniper berries. Oh yeah, I have been over 170mph on my buddies Hyabusa.

 

[Tzed250]

Fuel Cars

Fuel cars do need a hot spark to produce max power, but they don't need it to run. the only reliable way to kill a nitro burning Hemi is to use fuel shut-offs. Incredibly The biggest use of nitromethane is to clean printing presses.

 

[Harley]

The reason why the fuel for RC planes smells like 927 is the castor oil.

Nitro smells like a diesel with a blown head gasket that has habeneros in the exhaust manifold. Is that a good picture for you?
Nhra, and this year Ihra limit nitro to ninety percent. Many teams lessen the amount of nitro as part of their tuneup.

The reason for going to ninety percent was to elminate carnage. Nitro by itself is very explosive. Its highly sensitive to shock. Nitro isn't shipped in containers larger than 55 gal because of this.

The Mags on a nitro car. One mag can knock you unconscious for a couple of hours. I don't think anybody knows how two feel. MSD had plans to come out with a more powerful system, however it was not allowed because of the hazard that it presented to the pit crew.

Gas burns at roughly a fourteen to one mix with air. Alcohol about seven, and nitro around two. Typically closer to one to prevent running lean.

As for compression ratios. I've heard mostly that top fuel cars run a low compression. Something around seven to eight. However nobody will tell you straight out what they are running. The low compression is needed to prevent the nitro from preignition from shock.

Also it takes roughly sixty degrees of ignition timing to run a nitro engine

Nitro is funny, in that it likes to be loaded. The more load you put on the engine the more fuel you can put in it.

 

[Fish]

I take nitro for my heart, and I like to be loaded.

 

[Harley]

I forgot something, but since Fish made a funny, I'll add a little more.

You can get somekind of medical problem from handling the stuff with out gloves. I forget the technical name. Basically it dialates the blood vessels in your flesh where you were exposed to it. Its almost the same thing that the nitro pills do for heart patients.

A gallon cost around thirty bucks. Last time I heard. Thats straight, not blended with methanol.

Robert is right about the fuel shut off. Because the motor in a fuel cars eats its own plugs by the end of a run. The combustion chambers are so hot that its pretty much a diesel by the end of a run. I don't know how chainsaw might be though. I don't imagine that it would eat its own plugs.

 

[Fish]

It's just my job.

 

[Harley]

I know Fish

I'm really just trying to make 200 posts.

 

[Rotax Robert]

Last season I heard it was at $38 per gal. Also I have heard of guys adding paint thinner to thier fuel mix when running 10% nitro in thier saws. whatever that gains you

 

[Tzed250]

Nitro Cars

The reason that Top fuel and Funny Cars run around 8 to 1 comp. ratio is because they are supercharged. Injected nitro dragsters run extremely high compression ratio. Nitro is very hard to start burning. That is what makes it a great racing fuel. The comp. ratio can be bumped to the sky without risk of detonation. Nitro run a very rich fuel/air ratio because nitro brings its own air with it. The oxygen is liberated during combustion. If you can picture 4 bathroom shower heads all running at once, that is how much fuel is being injected into a nitro burning Hemi at WOT.

 

[My2cents]

All this discussion brings a question to mind: THe small R.C. engines are equiped with a glow plug for the initial starting of the engine. Once the engine is started the engine deisels without an ignition system. I'm thinking the compression ratio of the motor is designed around the flash point of the fuel. With all said, can adding small amounts of nitro methane to normal fuel mixtures increase chainsaw preformance without doing wear/damage to the saw.