I hope this isn't a dead thread. There's no such thing as free energy. Maybe not, but what about waste energy retrieved from the exhaust system? Wrapping small bore copper pipe round the downpipe below the exhaust manifold could, (depending on flow rate), turn any water fed through the pipe into very hot steam.
Would feeding this high temperature steam into the inlet manifold between carb (or fuel injectors) and engine do any good? Also, what about heat transfer from the exhaust downpipe to the copper pipe? If the manifold cools even slightly, the exhaust going through it would cool and contract; droping backpressure. Enough to make a difference? I don't know. Adding water reduces pre-ignition (knock); it was used on London buses after WW2 because of the poor quailty fuel available. Given that we've got better quality fuel now, would adding steam mean the engine could run on a leaner mixture (plus maybe a slightly higher compression ratio) without overheating?

I think the whole idea was shelved because the public at large are mainly stupid and would not keep the car filled with water, and if it run out of water with higher compression and weaker mixture things could go pop pretty quick, also there is the problem of creating the steam in the first place when the engine is cold using the waste heat from the exhaust gas. Also when dealing with steam explosions with a similar force to that of gunpowder are a real risk should anything go wrong with the injection and the feed system was allowed to pressurise excessively (got blocked), and all with very little gain in power.

Removing energy from the exhaust gases, that's what a turbocharger does.

My boiler is oil fired (kerosene). Quoted efficiency is 94% which is pretty good and is demonstrated by the coolness of the flue gases.

I take your point about reliability, mine stopped working just before Christmas. Apparently the EU commission introduced a new set of rules which reduced the sulphur content of heating oil from 250 parts per million (ppm) to 8 ppm. They didn't bother to tell anyone except the oil companies and sulphur is of course a lubricant. As a result, boiler fuel pumps have been seizing up all over the country - the Worcester Bosch chap who changed mine told me he's changed 16 in Lincolnshire alone. They've now changed the materials in the pump to cure the problem - I hope.

I'm glad I don't run my wife's ZX on heating oil

Derek

I can see how a small amount of hydrogen could improve power or MPG, not by being a source of fuel but as a means of enabling more complete combustion of the fuel/air mix - maybe similar to the LPG diesel kits? However at some (low) point there's not going to be enough air to burn the fuel so maybe along with the safety aspects this is the reason it hasn't been adopted.

I wonder how many people using these 'kits' have told their insurance companies that they have a on board hydrogen/oxygen 'generator' in their car? I'm sure the insurance companies would be impressed...

Steve.

Removing energy from the exhaust gases, that's what a turbocharger does.

OK DericW, point taken about turbochargers but not all cars have them. Plus what all modern cars do have is a catalytic converter, usually fitted close to the turbocharger. Exhaust gas (still pretty hot) goes into it, hydrocarbons are burned off, resulting in the exit gas being very hot. You can't take heat from the cat (they only work properly when fully hot) but what about wrapping the water tubing round the exit pipe?

Dean has a good point; equiping todays non mechanically minded drivers with a high pressure steam system that must be kept filled is perhaps not wise, but a friend of mine made a much cheaper basic version; gravity feed to copper pipe wrapped around the exhaust, feeding unpressurised steam straight into the carb (this was on an old VW van). He got about 3 mpg more out of it. Basically this was just a test rig but a year later he stopped driving so never followed it up.

I had a V6 auto XM. When driving back from Ullapool (north of Inverness) to Dundee the head gasket blew. Not enough to stop the engine, but water found it's way into at least two cylinders. I carried on driving (foolishly; it eventually cost me an engine) and found my average fuel consumption had dropped to 33 mpg.

One thing people have noticed is that petrol engines with steam injection don't get the usual carbon buildup on the piston crown and cylinder head. Maybe the addition of water allows the existing fuel to burn more completely. Engine runs cleaner; more power and/or lower fuel consumption.

Just a quick add on; have a look at this. http://cgi.ebay.co.uk/1998-FIAT-COUPE-BLAC...3A1|240%3A1308=

Aquamist water injection system (System 2s fully mapped)

There's at least one company making a commercial water injection system. That car looks like a bit of a road rocket. Not an XM, but..........................

I remember a video doing the rounds where a 'mechanic' dribbled water into the induction system of a engine to de-coke it. It does work but the chances of knackering up the engine but pouring water into it are too great to persuade me to try it. I'll just wait until the head cracks and do it then...

Steve.

And I remember when decokes were essential at 10,000 miles intervals max. With the vast improvements in fuel and combustion technology it's now "life of the engine, gasket or head failure". And with twin OHCs, hydraulic tappets and belt drives to contend with, I'm glad!

Derek

....and two cylinder banks Dean? Even changing the sparkplugs on the rear bank is awkward and often missed apparently. They too have an extended life these days, 75,000 miles instead of the old 10,000 with clean and regap at 5,000.

Derek

PS My plugs are due for replacement in about 2,000 miles, and yes I will be changing the rear bank.

Thats the problem with transverse engines, im working on a 70's v8 at the moment
Its soooo easy to get to everything and being carbed its a doddle to work on too

D