Fuel

Octane

The octane number is a measure of the resistance to knocking of a fuel, particularly gasoline. Knock resistance refers to the ability of fuel in an air-fuel mixture to be compressed (with the accompanying temperature increase) without undergoing self-ignition. Octane is a component of gasoline, and it is given a rating of 100. It is often mistakenly assumed that the octane number indicates the amount of octane in gasoline. The higher the octane number, the better the fuel is resistant to unwanted premature combustion, also known as pinging or knocking.

In the case of E10 gasoline, the octane number is usually around 95, which means it has good knock resistance for most modern gasoline engines. However, it may not be suitable for older engines.

Pinging or knocking

Pinging, also known as detonation or knocking, occurs when the air-fuel mixture in the combustion chamber does not ignite uniformly but spontaneously ignites before the spark plug ignites it. This results in multiple flame fronts moving and colliding in the combustion chamber, causing a ticking or knocking sound, resembling marbles rattling in a bag.

Pinging can be harmful to the engine as it creates additional pressure and temperature, which may damage pistons, valves, and other engine components. It can also lead to power loss and irregular engine operation.

Pinging is often caused by various factors, including incorrect fuel composition, low octane rating of the fuel, excessive engine cooling, excessive engine load, or incorrect ignition timing. To prevent pinging, higher octane gasoline can be used. When using higher octane gasoline, the ignition timing should be slightly advanced. In the past, mechanics would advance the ignition timing slightly when the customer filled up with premium (Super) gasoline.

Lead additive

In the past, lead was added to increase the octane number, specifically tetraethyl lead. This lead additive also provided lubrication to the valve guides and protected the exhaust valves and valve seats from knocking. Due to the harmful effects of lead, it is no longer used in regular gasoline, and lead substitutes are available in the market. However, lead substitutes do not work as effectively as genuine lead. With TetraBOOST, you can add genuine tetraethyl lead to the fuel, recreating the fuel your classic car was designed to run on when it left the factory.

Vaporlock

Vaporlock is a phenomenon that can occur in a vehicle’s fuel system, especially in gasoline engines. It happens when the liquid fuel in the fuel lines or carburetor changes into vaporized fuel, obstructing the normal fuel supply to the engine. This can lead to power loss, stuttering engine performance, and even a stalled engine. Additionally, vaporlock prevents a warm engine from starting. The problem becomes more significant at higher altitudes due to the lower air pressure.

Ethanol, an alcohol often blended with gasoline in fuel mixtures such as E10 (10% ethanol, 90% gasoline) or E5 (5% ethanol, 95% gasoline), can increase the risk of vaporlock. Ethanol has a lower vapor pressure than gasoline, making it evaporate more readily at lower temperatures. This evaporation can increase the pressure in the fuel lines and interrupt the fuel supply.

The use of fuel mixtures with a higher ethanol content can increase the risk of vaporlock, especially in high temperatures. Older vehicles or those with less advanced fuel management systems are more susceptible to this issue. TetraBOOST E-guard 15 neutralizes ethanol up to 15%, reducing the occurrence of vaporlock.

Stoichiometric ratio

The stoichiometric ratio refers to the ideal chemical ratio between the quantities of fuel and oxygen required for complete and optimal combustion. For gasoline, the stoichiometric ratio is the ideal balance where there is exactly enough air available to fully burn all fuel molecules.

For gasoline, the stoichiometric ratio is typically referred to as the air-fuel ratio, with about 14.7 grams of air required to burn 1 gram of fuel completely. This corresponds to a ratio of approximately 14.7:1 for the air-to-fuel mass mixture.

When the mixture in the combustion chamber has this ideal ratio, efficient combustion is achieved, with most fuel molecules fully converted into carbon dioxide (CO2) and water (H2O). This results in optimal energy output and minimal emissions.

If there is too much air in relation to the amount of fuel, it is considered a “lean mixture.” This can result in increased fuel consumption and reduced power output.

Conversely, if there is too much fuel in relation to the amount of air, it is considered a “rich mixture.” This can lead to incomplete combustion, increased emissions of harmful substances, and reduced fuel efficiency.

Maintaining the stoichiometric ratio is crucial for the proper operation of the engine. Modern vehicles with fuel injection systems use sensors to continuously control and optimize the air-fuel ratio.

RON

The term RON, often displayed on fuel pumps at gas stations, stands for Research Octane Number. It is a measure of gasoline’s knock resistance at lower engine speeds, as used in laboratory tests. The term MON stands for Motor Octane Number, which measures gasoline’s knock resistance at higher engine speeds, as experienced in practical driving conditions.

Volatility

Volatility refers to the extent to which gasoline evaporates at different temperatures. Higher volatility fuel evaporates more easily and can provide better cold-start performance.

Fuel Additives

Fuel additives are chemicals that can be added to gasoline to improve certain properties, such as fuel system cleaning, stabilization, lubrication, or enhanced combustion.

Aromatics

Aromatics are a class of chemical compounds found in gasoline, such as benzene, toluene, and xylene. They can affect engine performance and emissions.

Oxygenates

Oxygenates are oxygen-containing compounds added to gasoline, such as ethanol or MTBE (methyl tertiary-butyl ether), to increase octane rating and reduce emissions of harmful substances.