The Best Kind of Gas to Use in a Supercharger
- A turbocharger drastically increases cylinder pressure, which subsequently increases the likelihood of knock (detonation). Engine knock is a damaging condition that occurs when fuel inside the combustion chamber ignites without a spark, similar to what happens in a diesel engine. This causes melted pistons and spark plugs, and can be prevented by more stable, high octane fuel. Always use the highest octane fuel available for your turbocharged engine.
- To heat things up a little, you should consider running either C114 race gas, or at least a fuel additive like 104+ Octane Booster. These additives will further decrease the possibility of engine detonation, which will allow you to run more boost. More boost equals more power, and that makes for lower time-slips. It is for this reason that many people install a manual "boost controller" that allows them to increase power with the turn of a knob or flip of a switch.
Some turbocharged performance have an octane sensor built in, and can automatically increase or decrease boost in accordance to the fuel being used. One fuel to avoid on the street is any type of alcohol or methanol; these fuel require a dedicated system capable of properly handling and metering them, and may well destroy any fuel system that was designed with their use in mind.
- For weekend or dedicated racing use, nitromethane is king. This liquid rocket fuel contains its own oxidizers, and can almost burn in the complete absence of air. This will work especially well with supercharged engines, as they are far better as pushing fuel into the cylinders than air. Bear in mind that nitro should only be used with a dedicated fuel system, or as a supplementary fuel.
- When it comes time to join the big boys, consider installing a supplementary fuel system. A supplementary system is one which stands apart from the primary system, and is used only for enrichment under boost conditions. Propane injection has been popular for decades, as its latent heat of vaporization can cool the pressurized intake charge and combustion chamber just when it's needed most. Propane is also a good choice because it's cheap, easily accessible, and does not require a fuel pump as it is stored under pressure. Alcohol, methanol, and nitromethane are also good choices for a fuel supplement. Water injection can be used as well to prevent detonation, but is obviously not a fuel itself.