This page details a simple water injection system without using the MF2, since water injection does not have to follow a fixed ratio like the air / fuel mixture, water will only be required at a certain engine operating range. This simple system has all the advantages of a full blown system, but without the complexity of wiring and mapping. By changing the jet sizes (hence the delivery rate), a wide range of engine sizes can be accommodated. The negative side of the system is the lack of refinements compared with the MF2 system eg.fault diagnostic abilities and precise delivery rate control.

This system can cope with cars which only need water to suppress detonation. As mentioned on previous sections, some engines on certain application do not have to endure all the punishment required on race track conditions. A modified road car occasionally suffers from detonation problems because the simplest way to gain power is to either increase compression ratio or winding up the boost pressure, sometimes without modifying the fuelling and ignition curves. In most cases substantial power increase can be obtained with the right operating conditions, but these adventurous conversions will run into detonation problems in high ambient air temperatures, especially when accelerating hard out of a long slow traffic jam. During these conditions, water injection is extremely useful to cool the engine internally until the car attains a reasonable speed so air can contribute to the standard cooling system. When installing the simple water injection system, the trip-in point of the pressure switch for the application should be just below the maximum boost pressure so consumption of water is relatively low. Only occasional checking of the water tank is necessary.

As the water delivery rate cannot be regulated without the MF2, the only what it can be metered is by installing different size water jets. A table is provided below for the purpose, the figure is based on the ERL 3-wire water pump (p/n 806050)

Size Rate Pressure