It’s been almost 40 years since lead was phased out of pump fuels. Today, there are an increasing number of racers who never bought a drop of leaded gasoline for the family sedan back in the day. Understandably, we get a fair amount of questions about lead and why it’s used in some racing fuels.
Lead is an element (symbol Pb) and has a number of industrial uses. For racing fuels, lead is not used by itself... it is actually added in the form of Tetraethyl Lead (also known as TEL). TEL is a liquid mixture which makes it more easily stored and injected.
Lead is used in racing fuels because it is a very effective octane booster. As a matter of fact, leaded fuels are often credited for allowing higher compression, higher efficiency engines in World War II era aircraft. Increased power made some WWII airplanes like the P-51 Mustang legendary performers!
Definition: specific gravity (noun) - the ratio of the density of any substance to the density of some other substance taken as standard, water being the standard for liquids and solids, and hydrogen or air being the standard for gases.
For fuels, specific gravity can be determined by dividing the density of the fuel (in units of pounds per gallon) by the density of water (8.325 pounds per gallon). Let’s look at one example.