The current leaders in water injection are these guys
Aquamist
It comes in three forms;
Charge cooling on an air to air intercooler, where atomised water sprays are used after the intercooler but well before the inlet plenum. This cools the charge into the combustion chamber and reduces detonation/helps combustion efficiency. Ignition and ECU parameters are not affected in any way whatsoever.
Charge cooling as above, but before the intercooler - usually only advised for racing purposes and not advised for road use.
Direct water injection, where atomised water spray is misted into the inlet plenum (or direct port) to dramatically reduce detonation and improve combustion efficiency. This is ideally suited to very humid climates (like Florida) but unfortunately the ECU has to be mapped for it, and if you run out of water - oops [img]images/graemlins/shocked.gif[/img] Not particularly recommended for the UK.
There are also external intercooler sprays, which do work, but unfortunately are triggered after the intercooler is hot and are therefore a 15 second waste of time [img]images/graemlins/tongue.gif[/img]
The first option is the best for a modded UK car, triggered by a mappable ECU with three inputs. Intercooler housing temp, intercooler air temp (after the intercooler), and turbo boost combine to give the "Fang" factor which is a prediction in time of when the engine needs a cool charge - basically means you aren't sat at the lights with a hot intercooler and no boost, with water pissing into your combustion chamber [img]images/graemlins/grin.gif[/img]
Inlet temperature drops of at least 16c can be had using this correctly, which when linked to maximum boost heat generation of a modified engine, can mean improved air/fuel combustion of up to 20% [img]images/graemlins/shocked.gif[/img] The bhp/torque increase depends on the type of engine and how much boost you're running, but hey, it must be worth something.
I'm finding out during the course of next month exactly how much it will give. Wish me luck [img]images/graemlins/cool.gif[/img]
Andiroo