I have a few questions concerning the use of Nitromethane as a gasoline additive.

1. Is it obtainable?

2. Will it mix with pump gas?

3. Would, say, 1 gallon of Nitromethane, mixed with 20 gallons of gas, make a difference?

4. What does it do to the octane rating?

I got this idea from another thread, but have now been giving it some more serious thought.

 

Nitromethane can indeed make more power, at the brutal cost of fuel efficiency. The reason why Nitro makes more power when properly tuned than the same engine on gasoline is because an engine can consume between 3-4 times as much nitro as gasoline with the same amount of air. The stored chemical (potential) energy within a volume of gasoline is (approximately, forgive me, I couldn't find the numbers) similar to the energy in the same volume of nitro. Stoiciometrically, nitro reacts with air around a 4:1 air/fuel ratio. Most people may remember that gasoline burns ideally at around 14.7:1 air/fuel. If the energy is the same between both liquids, then the only way we can get more power out this engine by switiching to nitro is because the engine will consume more than 3 times as much fuel for the same amount of air that is induced into the engine (through the carburetor). NHRA top-fuelers run about a 4:1 ratio in their motors, which consume a frightening amount of fuel in that short 1/4 mile burst.

Chemically, you could improve the power in your engine by increasing the jet size in the carburetor, or by tuning the fuel injectors to shoot more fuel per volume of air. Realistically, nitromethane does not mix favorably with gasoline, and apparently creates tragic "thermal stresses" that will toast an engine in short order if a significant blend of this fuel is used (<5% nitro by volume). Nitromethane does mix favorably with Methanol, and carefully controlled mixtures of this fuel are widely used in the NHRA. Methanol also aids in "taming" the undesirable traits of nitro.

Nitromethane is CH3NO2
Methanol is CH3OH

In fact, below 97 degrees farenheit nitro will not even burn. The bottom line is that unless the fuel mixture is tuned to be far richer than a gasoline engine setting, the addition of nitro to gasoline would be quite detrimental. Also, the timing requirements change because of the use of this fuel. NHRA guys run 60-64 degrees advance with full Nitro blends. TK

 

Ok, here's the numbers:

Chemical stored energy available for reaction:

gasoline (assume 100% ocatane, C8H18): 125 kJ/mol

nitromethane (assume 100% CH2NO2): 113kJ/mol

as you can see, chemically the nitromethane would be weaker as a fuel additive than gasoline itself. The only way to unleash the power in Nitromethane is to crank up the amount of fuel you can put in the engine, like running a 4:1 a/f ratio instead of a 14:1. TK

references:

National Institute of Standards and Technology (NIST), Chemistry webpage

 

Wow! Great class.
Thanks,
zanny