KISS this shit goodbye .
http://en.wikipedia.org/wiki/Internal_combustion_engine
you make an electrospray sparkplug that gets refilled with few drops . Water will need much less voltage if in a vacuum . Basically you spark the water out , then ignite it using same sparkplug
who needs gas intake anyways , all the gases you need are in the water . The vacuum will make it so easy to blast out the water in atomized steam form then gets blasted again using the same sparkplug. just round-off the air intake camshaft or weld it shut . When the piston goes down thats when you zap your few droplets of water thats in your spark plug and make the gaz expand in the chamber as the piston is pulling . The piston will then compress the ionized gas the you spark that shit again then BOOM . Thermal ignition shockwave or w/e you wanna call it . The few drops of water get refilled in the sparkplug by gravity basically , very simple . Exhaust that the steam out and start again. Im pretty sure the motor would run cool enough that this would work.
Maybe install a laser in it or w/e , might not even be needed. Ppl have got to think how to apply it to an engine, not just making lots of bubbles .