Question: What is a stoichiometric mixture?
Answer: A stoichiometric mixture is the ratio of air to fuel which, when combusted, results in all elements of the mixture being used without any elements left over. Combustible mixtures range from an air-to-fuel ratio of about 8:1 to 18:1. However, a stoichiometric mixture has a ratio of 15:1. While this mixture will result in the fewest combustion byproducts, it may not be advisable to operate your engine at the stoichiometric ratio. Such a mixture may result in the peak exhaust gas temperature. Refer to your pilot's operating handbook for specific guidance on setting your aircraft's mixture. For more on leaning technique, see this article from Flight Training magazine.