Water injection (engine)

In internal combustion engines, water injection, also known as anti-detonant injection (ADI), can spray water into the incoming air or fuel-air mixture, or directly into the cylinder to cool certain parts of the induction system where 'hot points' could produce premature ignition. In jet engines it increases engine thrust at low speeds and at takeoff. In internal combustion engines, water injection, also known as anti-detonant injection (ADI), can spray water into the incoming air or fuel-air mixture, or directly into the cylinder to cool certain parts of the induction system where 'hot points' could produce premature ignition. In jet engines it increases engine thrust at low speeds and at takeoff. Water injection was used historically to increase the power output of military aviation engines for short durations, such as dogfights or takeoff. However it has also been used in motor sports and notably in drag racing. In Otto cycle engines, the cooling effects of water injection also enables greater compression ratios by reducing engine knocking (detonation). Alternately, this reduction in engine knocking in Otto cycle engines means that some applications gain significant performance when water injection is used in conjunction with a supercharger, turbocharger, or modifications such as aggressive ignition timing. Depending on the engine, improvements in power and fuel efficiency can also be obtained solely by injecting water. Water injection may also be used to reduce NOx or carbon monoxide emissions.