I've looked on tinternet at modern systems and they all seem to pipe cold water straight to the inlet manifold, they put some form of jet in the pipe to limit the flow and use inlet vacuum to suck the water into the engine. The idea is the high vacuum and small jet size combine to vapourise the water as it enters the manifold.
The bloke who modified the Daimler used a different technique altogether. He used an old BL plastic header tank (Marina I think) The water was then piped into an old SU carb float bowl. From there he used small bore stainless tube and removed and drilled two holes in the Daimler exhaust manifold. He then tapped the holes and used some type of plumbing fittings which screwed into the prepared holes. He then pushed as much pipe into the exhaust manifold as he dared, in one fitting and out the other and simply tightened the fittings onto the pipe to produce a gas tight seal. The business end of the pipe was simply fed into the air cleaner downstream of the filter. The result was a superheated steam fed more or less straight into the engine. Emissions were virtually nothing and performance and mpg were greatly enhanced.
He even contacted Leyland at Longbridge to try and get them interested but they didn't want to know. He used to run round in a Mini Countryman (remember them?). He had also done the mod on the mini and the local paper, The Express and Star actually did a full page spread on this fellow and road tested the car. He picked up their motoring correspondent early one morning filled it to the brim at the nearest petrol station (£3.20 I think!
) then the guy from the paper took over. He drove it hard to the coast and back then did some mixed town and country driving around Stratford and Warwick then came back through the middle of Birmingham and onto Wolverhampton then topped the tank back up to the brim. He was totally amazed that this car had been doing nearly 100 mpg and also noticed that power was way up on the standard car.Now that I've bought a petrol BX I've been toying with the idea of trying it out. I wouldn't go so far as drilling the exhaust manifold but maybe wrap some cupro nickel pipe around it for similar results.