We also replaced the large. Need help finding what you are looking for? The ratio of this mixture affects your fuel economy, performance, reliability, or even if your car runs at all. What is the optimum air fuel ratio on methanol? I heard a few different opinions. That is 3.
When designing an engine for a particular fuel, it's important to know how much air is needed to completely burn a certain amount of fuel. AFR tells you how many parts of air are mixed with each part of fuel. The stoichiometric ratio is the perfect ideal fuel ratio where the chemical mixing proportion is correct. Boiling point of methanol is Fuel doesn't burn on its own.
That is, if methanol is leaned out to an air to fuel ratio suitable for highway use, it is similar to 99 octane gasoline for detonation resistance. Why air density should concern a tuner: For maximum engine performance you need the correct air to fuel ratio, we all know this!
Fuel injection jetting was adjusted until an optimum spark plug reading was achieved. The actual air to fuel ratios by air to fuel weight would be: gasoline: About 5 to 5. Here are some examples of fuels and typical stoich ratios for each: C This means that for every kg of air, 0.
Fortunately methanol detonation or pinging is quite audible, so if you hear any "rattle" you must stop immediately and richen the fuel settings. Combustion is basically a chemical reaction called oxidation in which a fuel is mixed with oxigen and produces carbon dioxide CO 2water H 2 O and energy heat.
That or they have temporarily perfected the lean-burn forced induction engine!Most general-purpose aftermarket performance carburetors are designed to deliver around a When designing an engine for a particular fuel, it's important to know how much air is needed to completely burn a certain amount of fuel.
So if we were running an engine on pure methanol, we'd have calibrated our wideband controller such that produces a display of 6. Inadequate fuel volume will not inhibit detonation or pre-ignition. In the case of pure methanol a ratio of approximately six to one, that is to say six parts of air to one part of fuel by weight. For gasoline, the optimum air:fuel ratio is The key with methanol is that it is very tolerant of a rich mixture provided you have plenty of spark energybut very intolerant of a lean mixture.
To determine the excess air or excess fuel for a combustion system we starts with the stoichiometric air-fuel ratio. Combustion is basically a chemical reaction called oxidation in which a fuel is mixed with oxigen and produces carbon dioxide CO 2water H 2 O and energy heat.
A rich mixture would be one with a ratio less than Good, but not perfect. AFR tells you how many parts of air are mixed with each part of fuel. The primary ingredient for the burn within the combustion chamber is the methanol, a type of alcohol that's very flammable.
Methanol CH3OH is the chemical formula. To get to the stoichiometric ratio for station pump fuel with a percent ethanol mix requires a jet area increase is necessary, as shown in Figure When burned all fuel and air is consumed without any excess left over. What is the optimum air fuel ratio on methanol? I heard a few different opinions. But at hp run Lambda 1. Divide your fuel mass flow rate by the density of a gallon of meth say 6. Y: Lud is right, the stoichiometric AFR for methanol is 6.Thermal engines use fuel and oxygen from air to produce energy through combustion.
To guarantee the combustion process, certain quantities of fuel and air need to be supplied in the combustion chamber. A complete combustion takes place when all the fuel is burned, in the exhaust gas there will be no quantities of unburned fuel. Air-fuel ratio AF or AFR is the ratio between the mass of air m a and mass fuel m fused by the engine when running:. The ideal theoretical air-fuel ratio, for a complete combustion, is called stoichiometric air-fuel ratio.
For a gasoline petrol engine, the stoichiometric air-fuel ratio is around This means that, in order to burn completely 1 kg of fuel, we need The combustion is possible even is the AFR is different than stoichiometric.
For the combustion process to take place in a gasoline engine, the minimum AFR is around and the maximum can go up to When the air-fuel ratio is higher than the stoichiometric ratio, the air-fuel mixture is called lean.
methanol afr- idle, mid and power range afr
When the air-fuel ratio is lower than the stoichiometric ratio, the air-fuel mixture is called rich. For example, for a gasoline engine, an AFR of For example, in order to burn completely 1 kg of ethanol, we need 9 kg of air and to burn 1 kg of diesel fuel, we need Spark ignition SI engines usually run on gasoline petrol fuel.
The AFR of the SI engines varies within the range rich to leandepending on the operating condition of the engine temperature, speed, load, etc. Modern internal combustion engines operate as much as possible around the stoichiometric AFR mainly for gas after-treatment reasons. Compression ignition CI engines usually run on diesel fuel. Due to the nature of the combustion process, CI engines always run on lean mixtures, with AFR between and The main difference, compared with SI engines, is that CI engines run on stratified non homogeneous air-fuel mixtures, while SI run on homogeneous mixtures in case of port-injection engines.
In order to understand how the stoichiometric air-fuel ratio is calculated, we need to look at the combustion process of the fuel. Combustion is basically a chemical reaction called oxidation in which a fuel is mixed with oxigen and produces carbon dioxide CO 2water H 2 O and energy heat.
Take into account that, in order for the oxidation reaction to occur we need an activation energy spark or high temperature. Also, the net reaction is highly exothermic with heat release. Step 4. Calculate the mass of fuel, which is 1 mol of methane, made up from 1 atom of carbon and 4 atoms of hydrogen.
Step 5. Calculate the mass of oxygen, which consists of 2 moles, each mol made up from 2 atoms of oxygen.See all 2 photos.
Methanol has come back in a big way, with many race cars making the switch and even some street vehicles running the stuff. This begs the question: What is it about methanol that gives it an edge over gasoline? A popular discussion among fuel enthusiasts is how energy-dense a particular fuel is.
For instance, in a gasoline engine, an air-to-fuel ratio of roughly In the case of methanol, an air-to-fuel ratio of 4 parts air to 1 part fuel is considered slightly on the rich side, but will allow the engine to make its maximum power. An engine that flows 1, cfm of air about 70 pounds worth means that on gasoline, the engine will consume about 5. If we do the same calculation on methanol, we get Anyone explaining that methanol "burns cool" is actually talking about the enthalpy or latent heat of vaporization of the fuel.
When a liquid changes into a vapor as it does in an internal combustion engine heat energy is required for this transformation. And since heat is the enemy in engines—leading to all sorts of problems like an overtaxed cooling system, detonation, and even melted pistons—the more heat energy a fuel can suck out of the combustion process, the better.
Gasoline, when it undergoes a phase change can suck out about BTUs of heat energy per pound of fuel, which results in a temperature drop. Methanol, on the other hand, takes BTUs per pound of fuel of heat energy to make the phase change. When we look at our above example of an engine flowing 1, cfm of air, the 5. This is what makes methanol such an effective fuel in forced-induction applications like turbocharging and supercharging, and it absorbs so much heat that an intercooler often isn't even needed.
Gasoline offers a fairly narrow tuning window. Methanol on the other hand, can go as rich aswhich is about 62 percent of its stoichiometric value of 6. In fact, many race engines run as rich as 3. In a gasoline engine, running rich can cause pops, stumbles and backfires, whereas methanol usually pulls through any overly rich mixture and just keeps making power.
Want to go on the safe side and run extra-rich? With methanol there's very little downside to doing so. Since methanol makes more power and is more friendly in supercharged and turbocharged applications, why don't we use it instead of gasoline? Because there are drawbacks.
It's also very corrosive, and can eat through fuel lines if left sitting. For racing, however, methanol makes for a very good fuel, so expect to see more of it at the track near you. Close Ad. Jason Sands writer. Share on Facebook Share on Twitter.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 e Gasoline is a mixture of hydrocarbons.
Its chemical formula is C8H The air fuel ratio for complete combustion is This means that our engine consumes This equals Divide by the CH3OH is the chemical formula. Methanol burns at a much richer mixture than gasoline does, between 5. Using our Focus engine from above with a 6. Using our Focus engine from above with a 1. Advantages to running methanol. First of all Methanol burns slower in the combustion chamber. The octane rating of methanol is around 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. 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. Lastly, generally methanol is significantly cheaper than race gas.
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 lph pump and cc injectors to make the power you had on gas, now you need 2 pumps and cc 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.
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. Nitromethane will generally make 2. 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.
Nitromethane is definitely not for everyone. There is however the possibility to use small quantities of nitro as a power adder. Snow performance even sales nitro in bottle form for this.Im a little confused about the correct afr using methanol and the different target that i supposed to have on the idle, mid and power range I would strongly suggest that you consider tuning in lambda as it will make the transition between different fuels so much easier.
Lud is right, the stoichiometric AFR for methanol is 6.Race-Mart® Racing with Methanol Part V - Air Fuel Ratios
The key with methanol is that it is very tolerant of a rich mixture provided you have plenty of spark energybut very intolerant of a lean mixture.
For this reason you're always best to aim richer and be happy with an engine that will make great power and offer good reliability. Full power FI - 0. There are a wide range of wideband units on the market that will do a great job. When tuning on methanol you are shooting for very rich AFR numbers and hence some sensors won't read rich enough. The NTK sensor I use will only read as rich as 0. I would suggest looking for a unit running the LSU sensor.
That's why I'm surprised. If ECM can reach 0.
It may well be due to a limitation imposed by the Motec controller. If you are gonna do tuning on methanol and can't afford the AFM I would suggest using a wideband with the NTK sensor, the Haltech methanol wideband would probably give you the range you need. A colleague of mine who drag races a methanol fuelled FJ20 powered rail uses the ECM and swears by it.
On paper the measurement range is ideal for methanol. I haven't personally had the opportunity to use one. Don't have an account? Register here.
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Unresolved Threads. Page 1. Cptuning Nelson Carreras. Ludo Ludovic Rousseau. Lambda 1 for methanol is 6. The rules are the same than pump gas around 6.
April 30, at AM at AM. May 1, at AM at AM. Simon Andre Simon. May 1, at PM at PM. May 5, at AM at AM.Burning fuels is a chemical reaction, and has to abide by a number of rules. Petrol is a Hydrocarbonwhich is made of Hydrogen and Carbon. Other additives in the petrol also add more elements, but for the purpose of this article, we'll just look at the hydrocarbons.
Under the temperatures and pressures involved, Nitrogen also forms some oxides, collectively referred to as NO X. Depending on the temperatures, and ratios of air to fuel, different products will be made, and also there will be different power outputs for each mix.
Air-fuel ratio, lambda and engine performance
The Ratios do not tell the full picture though. They are the perfect ratios for a well mixed air and fuel vapour. In an engine, the mixing takes place very quickly and a perfect mix is impossible. Introductions like Swirl flaps or Disturbed Air Admittance valves agitate the air going in to mix the air and fuel better, but still, a perfect mix can't be attained.
Inside the cylinder will be a cloud of vapour, with some patches richer in fuel, and others leaner. The fuel can be accurately controlled, so the limiting factor in a Normally Aspirated petrol engine is the amount of air. To achieve the best power, all of the air has to be used as efficiently as possible, so the mixture will be enrichened by adding more fuel. The AFR for maximum power is usually betweendepending on how well mixed the vapour was beforehand.
The extra fuel increases the likelihood of the free oxygen being closer to a fuel molecule for the reaction. Some fuel will be wasted as there is an excess in the cylinder, but it helps ensure all of the air is used to it's full effect.
Likewise, running lean is better for economy. Where economy is concerned, you are looking to use all of the fuel injected by having an excess of air. Free oxygen taken into the cylinder will be wasted but the priority for an economic tune is to avoid wasting fuel. Lean running will increase the temperatures of the combustion, and will also make more of the Nitrogen in the air oxidise into Nitrogen Oxides NO and NO 2Nitrous Oxide is N 2 0 and a different kettle of fish.
The excess heat if unchecked can cause engine and Catalytic Converter damage, and the NO X is an undesirable air pollutant. This chart shows the resultant gasses from burning petrol at different AFRs.