We have decided to start a discussion on different types of fuel. In this article we will explain the pros and cons of each to help you make a more informed decision on your next project. We will start with discussing Gasoline, Methanol, and Nitromethane to explain why Nitro and Alcohol make more power. Our Next article will discuss different grades of gasoline as well as pure ethanol and e85.
Gasoline is a mixture of hydrocarbons. Its chemical formula is C8H18. The air fuel ratio for complete combustion is 14.7:1 called stoichiometric. This means that our engine consumes 14.7 pounds of air for 1 pound of fuel. Gasoline has approximately 18,400 BTU/lb . Using an air flow calculator this focus engine would consume 247cfms at 7000rpms with 100% VE. This equals 22.17lbs of air per min. Divide by the 14.7:1 ratio and that would get you 1.5lbs of fuel. Multiply that by the 18,400 and your engine would produce 27,600btu’s of energy at 7000rpms.
CH3OH is the chemical formula. Methanol burns at a much richer mixture than gasoline does, between 5.0:1 – 6.0:1. That’s 6lbs of air to one pound of fuel. Methanol has approximately 9,500 BTU/lb. Using our Focus engine from above with a 6.0:1 ratio our motor would use 3.69lbs of fuel. Multiply that by the 9,500 btu’s per lb of alcohol and our motor would be making 35,055btu’s at 7000rpms.
Nitromethane is a fuel that is used mostly in specialized drag racing classes such as “Top Fuel Funny Cars” . Nitromethane’s chemical formula is CH3NO2. The oxygen in nitromethane’s molecular structure means that nitromethane does not need as much atmospheric oxygen to burn, part of the oxygen needed to burn nitromethane is carried in the fuel itself. Typical A/F ratio for nitromethane is 1.7:1 and nitromethane has an energy content of 5,000 BTU/lb.Using our Focus engine from above with a 1.7:1 ratio our motor would use 13.04lbs of fuel. Multiply that by the 5,000btu’s per lb of nitro and our motor would be making 65,200btu’s at 7000rpms.
Advantages to running methanol
First of all Methanol burns slower in the combustion chamber. The octane rating of methanol is around 110 octane. Since the octane rating of methanol is so much higher than gasoline both boost, Compression and timing can be increased. The biggest advantage of Methanol is its inability to detonate. The way the flame front travels accross the combustion chamber makes it impossible to detonate.
Secondly, Methanol cools down the intake air temperatures entering the cylinder head so effectively that on a forced induction cars you don’t need an intercooler. Also, on certain applications with enough methanol no radiator is needed either. I only recommend this on purpose built drag cars.
Since the Air Temperatures are so much colder and the fuel produces more energy per lb. The engines with generally pick up 5-15% more power just by switching fuel. Even more by the added boost pressure, compression and timing.
Lastly, generally methanol is significantly cheaper than race gas. Between $1.50-3.00 a gallon, but remember you will need twice as much.
Disadvantages of alcohol
First of all Methanol uses 2 times the amount of fuel that gasoline does. This means you need twice the fuel system you had. If you had 1 255lph pump and 1000cc injectors to make the power you had on gas, now you need 2 pumps and 2000cc injectors. Also, you need bigger fuel lines and you might need more capacity in your tank.
Secondly Methanol is extremely corrosive. When methanol comes in contact with bare aluminum it can corrode the metal. Any aluminum surfaces should be hard anodized to prevent this. Even though it doesn’t seem like it, gasoline has a mild lubricating property which keeps the friction in your fuel pump and injectors to a minimum. Pure methanol, however, has no lubricating properties. I recommend adding an off the shelf alcohol lubricant to solve this problem. Alcohol can also be bad on rubber and plastics to confirm that all of your fuel system is compatible. Also, make sure to seal your alcohol containers well to make sure it doesn’t absorb water.
Lastly, Alcohol can be hard to start in cold temperatures which is why many racers prime there motors on gasoline then switch to alcohol.
In my opinion, alcohol isn’t for every body, but for some, it’s benefits far outweigh it’s disadvantages.
Advantages of Nitromethane
There is only 1 advantage to nitromethane and that is POWER. Nitromethane will generally make 2.3 times the power of gasoline with everything else the same.
Disadvantages of Nitromethane.
First of all, it is very explosive which can be quite dangerous in the wrong hands.
Second of all, it is very corrosive and will produce large amounts of nitric acid in vapor form when combusted, making the use of a proper gas mask essential by the driver, and for those close to the car in the start area.
Lastely, nitromethane is very expensive
Nitromethane is definitely not for everyone. Leave running pure nitro to TOP FUEL teams that can rebuild there motors after every pass. There is however the possibility to use small quantities of nitro as a power adder. Many people have has success with mixing 5,10 and 15% nitro with methanol and using it as fuel to make good power gains.
Others have had good luck with mixing small amounts of nitro into there water/meth systems and picked up 30-50hp without changing anything. Snow performance even sales nitro in bottle form for this.
Keep in mind that anytime you experiment with anything like this there is always the chance of failure with engine components. This is not for everyone and is really only for those who want the absolute most power out of there Engines.