Below a general message to all our GEM Fuel drivers, tuners, team owners and other customers. Running GEM Fuel creates an excellent performance boost to almost all engines (atmospheric or turbo). To ensure that this performance will remain in your car, we have written down a few best practices for the use of GEM Fuel. Please share this information with your engine mapper or tuner.
NOT the same as E85
GEM Fuel has the same AFR properties as common E85 fuel. For this reason the same injector size and the same fuel mapping as with E85 can be used as a starting point in your mapping. Since in reality the mixture of E85 can vary over the season, it is advised to always check the engine mapping when GEM Fuel is applied. Please note that GEM Fuel and E85 are similar, though NOT the same! GEM Fuel creates a better performance because of the methanol content and requires correct mapping at all times.
Octane numbers (RON/MON) are not the only performance driver
The octane rating of GEM Fuel is more or less equal to E85. Depending on the exact composition of E85, a difference of +-1 point in both directions can occur. It is good to know that for alcohol-based fuels like GEM Fuel the octane number is not directly comparable to ordinary gasoline, as far as engine-knock is considered. The strong charge cooling effect of the alcohol strongly helps reducing engine knock. This effect is not taken into account in the classical RON and MON octane test. Summarized: to be sure about engine- safety and get the maximum performance from your engine: check the ignition mapping on a dyno, using appropriate knock detection.
Use Copper Spark plugs with correct heat grade
Especially in highly turbocharged engines with high in-cylinder temperatures, a specific effect can happen in alcohol-based fuels. In presence of materials that act as a catalyst, hydrogen can be formed during combustion. The same material can help ignite the hydrogen, which can be a starting point for the combustion of all fuel in the cylinder. Since this start of combustion is uncontrolled such materials are unwanted in the cylinder. Well known is the catalyst function of platinum or iridium. Both materials are nowadays often used in premium spark plugs. These spark plugs are not advised for alcohol fueled racing cars. Use plain copper spark plugs with an appropriate heat grade. Main reason for application of precious metal plugs is their long life (often over 100.000 km), which is not relevant for racing cars.
Monitor Fuel System
Both petrol and alcohol are strong solvents. Not all materials are compatible with these fuels or mixtures of them. Especially some rubbers and plastics are sensitive for this and can swell or solve. GEM Fuel contains methanol, which has different properties than the ethanol from E85. It is advised to regularly check filters in vehicles that are fueled with E85 or GEM Fuel. Cases are known where the fuel tank foam was found in filters, or some debris or coating from jerry cans was found in the inlet filter of the fuel pump. Regularly check your Fuel System!
Condensation of fuel at start up
Instead of the boiling trajectory of traditional petrol, alcohols have a boiling point. 65 °C for methanol and 78 °C for ethanol. This has some influence on the engine: it is common that some fuel (petrol or alcohol) condenses into the engine oil. Especially on competition cars, which are often running quite rich when cold, this can be quite some amount. On petrol cars this fuel slowly evaporates during the warming up of the engine. On alcohol fueled cars all alcohol will boil out of the oil when the oil reaches the alcohol boiling point. With a closed positive carter venting system this will increase the fueling amount into the engine. This will not induce any problem, although one should be aware of it when setting up a Lambda control or creating a new mapping.