It has an extra stroke where water is injected and the steam pushes the piston back down, pretty damn cool. And yes, found this on Digg :P

http://www.gear6.net/2006/03/sixstroke_engin.html

thats freeken cool, my questions is wont cool water on hot metal cause it to crack?

That's awesome he's 75 and still gettin his hands dirty

Originally posted by youkickedmydog
thats freeken cool, my questions is wont cool water on hot metal cause it to crack?

don't people already inject water during the normal combustion cycle anyway? there is alot of talk about water injection on this site. Also, the fuel isn't exactly hot to begin with either and it doesn't cause cracks. It doesn't say its ice water going in there... also, there is water circulationg throughout the motor, whats a little in the combustion chamber going to do?

durr I forgot about water sprayers, Never mind then, I guess the day where you need to fill up with some water to go on a road trip is comming.

Originally posted by youkickedmydog
durr I forgot about water sprayers, Never mind then, I guess the day where you need to fill up with some water to go on a road trip is comming.

I'm already there. I take 5 gallons of methanol with me to the track every time I go, and have to check the sprayer level every fillup...

very interesting. it combines the portabily of a 4-stroke engine with the efficiency of a vapor power system. vapor power systems used in typical electric power generation are MUCH more efficient than an automotive engine but are ill-suited for transportation due primarily to size and start-up time (most are run continuously 24/7). i'd really like to see what the thermal analysis of such a cycle is. in a regular gasoline engine it might not be that beneficial though... diesels are much more efficient to begin with and would probably make better use of the system. plus ideally you don't want to be excessively cooling your engine as higher temps = higher efficency (until things start to melt).

i imagine you need a pretty high pressure water injector to make this work though... cracking prolly isn't a problem as you're probably not dropping the internal temps of the engine that significantly. the water is being vaporized on contact and the isentropic expansion is being converted to work. i doubt the volume of water is anything close to what would be needed to quench the internals.

Very cool and interesting, definetley a cool concept

Must have more information, crave data, need more!

i'm gonna go ask my thermodynamics prof about this...

is the cylinder pressurized prior to water injection? if that's the case then part of your work is being used for the operation of a high pressure pump for the water injection...

i'm guessing the extra 2 strokes are in between the exhaust and intake stroke. once the the exhaust valve closes during the exhaust stroke, water is injected - which vaporizes and forces the piston down creating a secondary power stroke? then during a second exhaust stroke the water vapor is removed. then the regular fuel intake stroke takes place?

this must be a PITA for cams though. you'd need either a second set of intake AND exhast cams or a cam with 2 separate open periods per cycle. idk if that's geometrically possible...

hmmm..

I like it!