One of the most common queries on my web site is the issue of water injection, when owners are trying to achieve the maximum from their turbocharged cars, every increase of power or damage limitation is a help so how about a solution that does both.

The first thing most Turbo charged car owners do to increase the performance of their car is to turn up the boost and increase the fuel and air mixture, some cars can handle extreme amounts of boost relative to the factory standard which would have been set for a little bit of economy to the sacrifice of speed and acceleration. The A series, O series and T16 engines are no different, they are capable of increased power so it is done frequently, the problem of detonation then occurs, at the point of detonation its time to back of the power or face serious damage. The more fuel and air into the engine will increase the power, the turbocharger compressing the inlet air however heats it, and the higher air temperature can lead to a lean mixture and detonation. In turbocharged engines the high pressure can lead to premature exploding in the cylinder prior to the spark from the ignition (Engine knock).

Well all of this leads to damage, primarily piston damage, holed pistons or cracked rings all of which can prove expensive, especially if your engine happens to be an eight valve turbo engine in a Maestro or Montego as replacement pistons are becoming a rarity. To combat this restriction a method of avoiding detonation is required.

Water injection has been used for a great number of years; in World War II it was used in some fighter aircraft to stop detonation of the air fuel mixture at high altitudes. It is also reported in some articles that the water was mixed with methanol in these fighters to stop the water freezing at high altitude.

Water injection lowers the chance of violent detonation by cooling the air, fuel mixture in the cylinder; it works in a similar way to an Intercooler by cooling the air compressed by the turbo charger. Once the fuel, air and water mix has been passed through the engine the water is expelled through the exhaust as steam, there is no chemical reaction between the water and the standard exhaust gases. This use of water in the system also prevents the build up of carbon deposits in the engine.

As well as damage limitation water injection can increase the power of the car in two ways, firstly because it increases the density of the fuel and air mixture entering the cylinders by cooling down the compressed air fed in by the turbo charger. The mist created when the water enters the compressed air turns into vapour that absorbs a large amount of the heat from the fuel and air mixture before it enters the combustion chamber. This denser air achieves greater fuel and air mixture in the cylinder at the time of compression.

Secondly, the use of water injection allows for an increase in torque, this is achieved by increasing the pressure within the inlet manifold prior to detonation. Because the pressure within the inlet manifold is increased the power produced at any given RPM is also increased thus improving the power output of the engine.

There are three methods of water injecting, these depend on where the water injectors are placed, they can be placed at the entrance to the inlet manifold, the second is at the exit pipe from the intercooler this is the most commonly recommended place. The third is at the entrance to the intercooler, although this is usually only carried out for motor sport purposes as excess fuel is injected as well to cool and not be burnt.

The best way to fit water injection is to purchase one of the many kits that are available from many suppliers, one of the biggest and most well known in the UK being Aquamist although Moto-Build sell a kit too. There are also DIY methods available using windscreen washer bottles and pumps.

Most of the commercially purchased kits include a water pump, a pressure sensor, nozzle, a solenoid or simple check valve, water filter, and plumbing facilities (some kits also may contain and air temperature sensor). A water reservoir is usually not supplied as a lot of people use their washer jet reservoir.

The kits available come with fitting instructions and fitting to the A series, O series and T16 engines all differ for example it is most common to fit the injector after the intercooler, fine on the O series and T16 engines but the A series turbo engine does not have an intercooler as standard so at the entrance to the inlet manifold might be a better place.

As the system is controlled by the pressure in the inlet manifold it is important to make sure the check valve is fitted to prevent water entering the engine under vacuum when for example the engine is idling. Another tip is to keep the lengths of tubing setting up the system as short as possible.

Prices for kits start at just over £300 but its worth spending some time on the internet searching because in the US the use of water injection is more popular hence the prices are cheaper.