All,
Just a thought as far as power in an internal combustion engine.

I know how the engine works, burns hydrocarbons and makes torque.

I've also seen SamuraiJack's posts on Hydrogen production and integration into engines. (Is he REALLY a samurai?)

What I've been wondering is if there is a way to utilize the heat produce by burning a fuel?
I've heard rumors of a "Six stroke" engine, in which, after the fuel, ignition, exhause cycle, a spray of liquid water is injected into the piston. Theoretically, the heat from the just-happened fuel cycle vaporizes the water, forcing the piston down with less, but still noticable force. The use of the heat would also cool the engine, eliminating the need for a water pump, radiator etc...

My main question here: Is the inside of a cylinder hot enough after firing to actually boil water?

There's some obvious trouble shooting to be done here, for example, tap water would rust the inside of the cylinder. (That's still bad right?) But the power increase would be moderately worthwhile.

Leave your thoughts if you would.

-out

From my knowledge, the heated gasses inside the piston have a certain pressure. By adding in cold water, youre effectively cooling down the gas inside causing a drop in pressure.

Water injection into the cylinder seem like an awful lot of effort to recover energy from an engine. You would need to build an engine from the ground up, and design it into the system in order for it to work well (I would think anyway). instead, why not fit a heat exchanger onto the exhaust. this is what is done with larger IC engines eg for power generation. the extra heat can be used to preheat the fuel, or the air intake, or provide building heating.

an alternative to this is the rankine cycle. basically, you use an alternative working fluid - something similar to what pumps round your fridge. you run this fluid around your heat source - in this case the heat exchanger you have bolted onto the exhaust pipe. the exhaust warms it up, turning it into a gas. you then run the gas through a special turbine, and use that to generate a bit more power (generally electricity). I know this works for systems of 100kW upwards. you can buy the parts with a bit of hunting on google.

Wikipedia has a good article:
http://en.wikipedia.org/wiki/Crower_six_stroke

The drawbacks pointed out in the article are significant.

Here's an alternate suggestion: An engine's cooling system is already hot enought to produce steam. (Just take off a radiator cap after a half-hour drive. No...wait...DON'T!!! Oh man. That's gonna leave a mark.) I think it would be simpler to use a the cylinder block as a steam boiler used to drive a separate steam engine. It may be a bit less efficient, but would keep the water completely out of the fuel/lubrication system and eliminate the problems it causes there. It also avoids completely redesigning the internal combustion engine (ICE).

A closed cycle would be needed unless you carry around a (heavy) tank of distilled water. A trade-off calcualtion would have to be made to see which method would be more efficient. (Including creation and distribution of the DHMO. ) My money's on the closed cycle.

This would be relatively easy to implement on a prius-style hybrid where the drive is totally electric. It would only run when the ICE was hot, providing extra power just when it was needed most.

Once...a very long time ago...

Now as to your question about the engine...
The ICE is an incredibly inefficent device in terms of energy recovery. There are so many calories that are wasted as heat by product that it really begs the question why we are not looking into it. This energy could be used for some very standard, useful things. Like preheated or even flashing the gasoline, running peltier generators and even basic steam turbines. After the CAT is done with it, we should he harnessing it for something. We could havest inside the engine, which would be the most likely place to start, but it would require retooling of the system. So I suggest we start by looking outside the engine at the high energy points of the manifold and the post cat exhaust It's all spare or waste energy that could be recycled if we put our minds to it.

That has been the focus of my research lately:
"What can we do to think outside the box and provide access to more energy for the common man?"

Once you start looking at the waste energy, you will be amazed.
SJ

There's a LOT of waste energy in an internal combustion engine. Find a way to harness it and the savings would be HUGE.

I'm pretty sure that there have been demonstrated working 6 stroke engines, though I'm not so sure that it'd be that great an idea where the winter climate makes keeping liquid water difficult to impossible.

Wikipedia has a good write-up on 6 stroke engines. A neat idea if they can overcome the problems of metal fatigue.

It might be an interesting idea hook an alternator up to a small steamer (run off engine heat) and generate oxyhydrogen and feed it back into the system. You get the catalytic effect without incurring the energy loss of generating the electricity. You also avoid complex gearing or engine re-engineering associated with directly applying the steam energy to the drive train.

I dunno if I'd use a steamer, but there are several good examples of external combustion engines which should be usable off of the engine cooling system. That would be a way to scavenge some of the waste energy.

Unfortunately, most of these applications are of limited power, and, of course, don't work at all until the engine has reached operating temperature. Add in the fact that you have to lug around the extra mass, and you've got something with limited application at best. Maybe it'd be useful to power a heater fan. Or maybe the water pump. After all, everything that you can take off of the crankshaft increases the available power to move the car.

Maybe in your country, it never reaches freezing temperatures in australia

The exhaust temp is perfect for boiling ammonia...as in absorption cycle (non mechanical) refrigeration; but instead we use some of the ~12% power we can recover from the fuel, to turn a freon pump for AC?