So does water injection but it makes a serious Horse Power increase.
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 sport 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.
[1] Water injection may also be used to reduce
NOx or
carbon monoxide emissions.
[1]
Water injection is also used in some turbine engines and in some turboshaft engines, normally when a momentary high-thrust setting is needed to increase power and fuel efficiency.